/* * Generic ring buffer * * Copyright (C) 2008 Steven Rostedt */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "trace.h" int ring_buffer_print_entry_header(struct trace_seq *s) { int ret; ret = trace_seq_printf(s, "# compressed entry header\n"); ret = trace_seq_printf(s, "\ttype_len : 5 bits\n"); ret = trace_seq_printf(s, "\ttime_delta : 27 bits\n"); ret = trace_seq_printf(s, "\tarray : 32 bits\n"); ret = trace_seq_printf(s, "\n"); ret = trace_seq_printf(s, "\tpadding : type == %d\n", RINGBUF_TYPE_PADDING); ret = trace_seq_printf(s, "\ttime_extend : type == %d\n", RINGBUF_TYPE_TIME_EXTEND); ret = trace_seq_printf(s, "\tdata max type_len == %d\n", RINGBUF_TYPE_DATA_TYPE_LEN_MAX); return ret; } enum { RB_BUFFERS_ON_BIT = 0, RB_BUFFERS_DISABLED_BIT = 1, }; enum { RB_BUFFERS_ON = 1 << RB_BUFFERS_ON_BIT, RB_BUFFERS_DISABLED = 1 << RB_BUFFERS_DISABLED_BIT, }; static unsigned long ring_buffer_flags __read_mostly = RB_BUFFERS_ON; #define RB_BUFFER_OFF (1 << 20) #define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) void tracing_off_permanent(void) { set_bit(RB_BUFFERS_DISABLED_BIT, &ring_buffer_flags); } #define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) #define RB_ALIGNMENT 4U #define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) #define RB_EVNT_MIN_SIZE 8U #if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) # define RB_FORCE_8BYTE_ALIGNMENT 0 # define RB_ARCH_ALIGNMENT RB_ALIGNMENT #else # define RB_FORCE_8BYTE_ALIGNMENT 1 # define RB_ARCH_ALIGNMENT 8U #endif #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX enum { RB_LEN_TIME_EXTEND = 8, RB_LEN_TIME_STAMP = 16, }; #define skip_time_extend(event) \ ((struct ring_buffer_event *)((char *)event + RB_LEN_TIME_EXTEND)) static inline int rb_null_event(struct ring_buffer_event *event) { return event->type_len == RINGBUF_TYPE_PADDING && !event->time_delta; } static void rb_event_set_padding(struct ring_buffer_event *event) { event->type_len = RINGBUF_TYPE_PADDING; event->time_delta = 0; } static unsigned rb_event_data_length(struct ring_buffer_event *event) { unsigned length; if (event->type_len) length = event->type_len * RB_ALIGNMENT; else length = event->array[0]; return length + RB_EVNT_HDR_SIZE; } static inline unsigned rb_event_length(struct ring_buffer_event *event) { switch (event->type_len) { case RINGBUF_TYPE_PADDING: if (rb_null_event(event)) return -1; return event->array[0] + RB_EVNT_HDR_SIZE; case RINGBUF_TYPE_TIME_EXTEND: return RB_LEN_TIME_EXTEND; case RINGBUF_TYPE_TIME_STAMP: return RB_LEN_TIME_STAMP; case RINGBUF_TYPE_DATA: return rb_event_data_length(event); default: BUG(); } return 0; } static inline unsigned rb_event_ts_length(struct ring_buffer_event *event) { unsigned len = 0; if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { len = RB_LEN_TIME_EXTEND; event = skip_time_extend(event); } return len + rb_event_length(event); } unsigned ring_buffer_event_length(struct ring_buffer_event *event) { unsigned length; if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) event = skip_time_extend(event); length = rb_event_length(event); if (event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX) return length; length -= RB_EVNT_HDR_SIZE; if (length > RB_MAX_SMALL_DATA + sizeof(event->array[0])) length -= sizeof(event->array[0]); return length; } EXPORT_SYMBOL_GPL(ring_buffer_event_length); static void * rb_event_data(struct ring_buffer_event *event) { if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) event = skip_time_extend(event); BUG_ON(event->type_len > RINGBUF_TYPE_DATA_TYPE_LEN_MAX); if (event->type_len) return (void *)&event->array[0]; return (void *)&event->array[1]; } void *ring_buffer_event_data(struct ring_buffer_event *event) { return rb_event_data(event); } EXPORT_SYMBOL_GPL(ring_buffer_event_data); #define for_each_buffer_cpu(buffer, cpu) \ for_each_cpu(cpu, buffer->cpumask) #define TS_SHIFT 27 #define TS_MASK ((1ULL << TS_SHIFT) - 1) #define TS_DELTA_TEST (~TS_MASK) /* Flag when events were overwritten */ #define RB_MISSED_EVENTS (1 << 31) #define RB_MISSED_STORED (1 << 30) struct buffer_data_page { u64 time_stamp; local_t commit; unsigned char data[]; }; struct buffer_page { struct list_head list; local_t write; unsigned read; local_t entries; unsigned long real_end; struct buffer_data_page *page; }; #define RB_WRITE_MASK 0xfffff #define RB_WRITE_INTCNT (1 << 20) static void rb_init_page(struct buffer_data_page *bpage) { local_set(&bpage->commit, 0); } size_t ring_buffer_page_len(void *page) { return local_read(&((struct buffer_data_page *)page)->commit) + BUF_PAGE_HDR_SIZE; } static void free_buffer_page(struct buffer_page *bpage) { free_page((unsigned long)bpage->page); kfree(bpage); } static inline int test_time_stamp(u64 delta) { if (delta & TS_DELTA_TEST) return 1; return 0; } #define BUF_PAGE_SIZE (PAGE_SIZE - BUF_PAGE_HDR_SIZE) #define BUF_MAX_DATA_SIZE (BUF_PAGE_SIZE - (sizeof(u32) * 2)) int ring_buffer_print_page_header(struct trace_seq *s) { struct buffer_data_page field; int ret; ret = trace_seq_printf(s, "\tfield: u64 timestamp;\t" "offset:0;\tsize:%u;\tsigned:%u;\n", (unsigned int)sizeof(field.time_stamp), (unsigned int)is_signed_type(u64)); ret = trace_seq_printf(s, "\tfield: local_t commit;\t" "offset:%u;\tsize:%u;\tsigned:%u;\n", (unsigned int)offsetof(typeof(field), commit), (unsigned int)sizeof(field.commit), (unsigned int)is_signed_type(long)); ret = trace_seq_printf(s, "\tfield: int overwrite;\t" "offset:%u;\tsize:%u;\tsigned:%u;\n", (unsigned int)offsetof(typeof(field), commit), 1, (unsigned int)is_signed_type(long)); ret = trace_seq_printf(s, "\tfield: char data;\t" "offset:%u;\tsize:%u;\tsigned:%u;\n", (unsigned int)offsetof(typeof(field), data), (unsigned int)BUF_PAGE_SIZE, (unsigned int)is_signed_type(char)); return ret; } struct ring_buffer_per_cpu { int cpu; atomic_t record_disabled; struct ring_buffer *buffer; raw_spinlock_t reader_lock; arch_spinlock_t lock; struct lock_class_key lock_key; struct list_head *pages; struct buffer_page *head_page; struct buffer_page *tail_page; struct buffer_page *commit_page; struct buffer_page *reader_page; unsigned long lost_events; unsigned long last_overrun; local_t entries_bytes; local_t commit_overrun; local_t overrun; local_t entries; local_t committing; local_t commits; unsigned long read; unsigned long read_bytes; u64 write_stamp; u64 read_stamp; }; struct ring_buffer { unsigned pages; unsigned flags; int cpus; atomic_t record_disabled; cpumask_var_t cpumask; struct lock_class_key *reader_lock_key; struct mutex mutex; struct ring_buffer_per_cpu **buffers; #ifdef CONFIG_HOTPLUG_CPU struct notifier_block cpu_notify; #endif u64 (*clock)(void); }; struct ring_buffer_iter { struct ring_buffer_per_cpu *cpu_buffer; unsigned long head; struct buffer_page *head_page; struct buffer_page *cache_reader_page; unsigned long cache_read; u64 read_stamp; }; #define RB_WARN_ON(b, cond) \ ({ \ int _____ret = unlikely(cond); \ if (_____ret) { \ if (__same_type(*(b), struct ring_buffer_per_cpu)) { \ struct ring_buffer_per_cpu *__b = \ (void *)b; \ atomic_inc(&__b->buffer->record_disabled); \ } else \ atomic_inc(&b->record_disabled); \ WARN_ON(1); \ } \ _____ret; \ }) #define DEBUG_SHIFT 0 static inline u64 rb_time_stamp(struct ring_buffer *buffer) { return buffer->clock() << DEBUG_SHIFT; } u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu) { u64 time; preempt_disable_notrace(); time = rb_time_stamp(buffer); preempt_enable_no_resched_notrace(); return time; } EXPORT_SYMBOL_GPL(ring_buffer_time_stamp); void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer, int cpu, u64 *ts) { *ts >>= DEBUG_SHIFT; } EXPORT_SYMBOL_GPL(ring_buffer_normalize_time_stamp); #define RB_PAGE_NORMAL 0UL #define RB_PAGE_HEAD 1UL #define RB_PAGE_UPDATE 2UL #define RB_FLAG_MASK 3UL #define RB_PAGE_MOVED 4UL static struct list_head *rb_list_head(struct list_head *list) { unsigned long val = (unsigned long)list; return (struct list_head *)(val & ~RB_FLAG_MASK); } static inline int rb_is_head_page(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *page, struct list_head *list) { unsigned long val; val = (unsigned long)list->next; if ((val & ~RB_FLAG_MASK) != (unsigned long)&page->list) return RB_PAGE_MOVED; return val & RB_FLAG_MASK; } static int rb_is_reader_page(struct buffer_page *page) { struct list_head *list = page->list.prev; return rb_list_head(list->next) != &page->list; } static void rb_set_list_to_head(struct ring_buffer_per_cpu *cpu_buffer, struct list_head *list) { unsigned long *ptr; ptr = (unsigned long *)&list->next; *ptr |= RB_PAGE_HEAD; *ptr &= ~RB_PAGE_UPDATE; } static void rb_head_page_activate(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *head; head = cpu_buffer->head_page; if (!head) return; rb_set_list_to_head(cpu_buffer, head->list.prev); } static void rb_list_head_clear(struct list_head *list) { unsigned long *ptr = (unsigned long *)&list->next; *ptr &= ~RB_FLAG_MASK; } static void rb_head_page_deactivate(struct ring_buffer_per_cpu *cpu_buffer) { struct list_head *hd; rb_list_head_clear(cpu_buffer->pages); list_for_each(hd, cpu_buffer->pages) rb_list_head_clear(hd); } static int rb_head_page_set(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *head, struct buffer_page *prev, int old_flag, int new_flag) { struct list_head *list; unsigned long val = (unsigned long)&head->list; unsigned long ret; list = &prev->list; val &= ~RB_FLAG_MASK; ret = cmpxchg((unsigned long *)&list->next, val | old_flag, val | new_flag); if ((ret & ~RB_FLAG_MASK) != val) return RB_PAGE_MOVED; return ret & RB_FLAG_MASK; } static int rb_head_page_set_update(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *head, struct buffer_page *prev, int old_flag) { return rb_head_page_set(cpu_buffer, head, prev, old_flag, RB_PAGE_UPDATE); } static int rb_head_page_set_head(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *head, struct buffer_page *prev, int old_flag) { return rb_head_page_set(cpu_buffer, head, prev, old_flag, RB_PAGE_HEAD); } static int rb_head_page_set_normal(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *head, struct buffer_page *prev, int old_flag) { return rb_head_page_set(cpu_buffer, head, prev, old_flag, RB_PAGE_NORMAL); } static inline void rb_inc_page(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page **bpage) { struct list_head *p = rb_list_head((*bpage)->list.next); *bpage = list_entry(p, struct buffer_page, list); } static struct buffer_page * rb_set_head_page(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *head; struct buffer_page *page; struct list_head *list; int i; if (RB_WARN_ON(cpu_buffer, !cpu_buffer->head_page)) return NULL; list = cpu_buffer->pages; if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev->next) != list)) return NULL; page = head = cpu_buffer->head_page; for (i = 0; i < 3; i++) { do { if (rb_is_head_page(cpu_buffer, page, page->list.prev)) { cpu_buffer->head_page = page; return page; } rb_inc_page(cpu_buffer, &page); } while (page != head); } RB_WARN_ON(cpu_buffer, 1); return NULL; } static int rb_head_page_replace(struct buffer_page *old, struct buffer_page *new) { unsigned long *ptr = (unsigned long *)&old->list.prev->next; unsigned long val; unsigned long ret; val = *ptr & ~RB_FLAG_MASK; val |= RB_PAGE_HEAD; ret = cmpxchg(ptr, val, (unsigned long)&new->list); return ret == val; } static int rb_tail_page_update(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *tail_page, struct buffer_page *next_page) { struct buffer_page *old_tail; unsigned long old_entries; unsigned long old_write; int ret = 0; old_write = local_add_return(RB_WRITE_INTCNT, &next_page->write); old_entries = local_add_return(RB_WRITE_INTCNT, &next_page->entries); barrier(); if (tail_page == cpu_buffer->tail_page) { unsigned long val = old_write & ~RB_WRITE_MASK; unsigned long eval = old_entries & ~RB_WRITE_MASK; (void)local_cmpxchg(&next_page->write, old_write, val); (void)local_cmpxchg(&next_page->entries, old_entries, eval); local_set(&next_page->page->commit, 0); old_tail = cmpxchg(&cpu_buffer->tail_page, tail_page, next_page); if (old_tail == tail_page) ret = 1; } return ret; } static int rb_check_bpage(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *bpage) { unsigned long val = (unsigned long)bpage; if (RB_WARN_ON(cpu_buffer, val & RB_FLAG_MASK)) return 1; return 0; } static int rb_check_list(struct ring_buffer_per_cpu *cpu_buffer, struct list_head *list) { if (RB_WARN_ON(cpu_buffer, rb_list_head(list->prev) != list->prev)) return 1; if (RB_WARN_ON(cpu_buffer, rb_list_head(list->next) != list->next)) return 1; return 0; } static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) { struct list_head *head = cpu_buffer->pages; struct buffer_page *bpage, *tmp; rb_head_page_deactivate(cpu_buffer); if (RB_WARN_ON(cpu_buffer, head->next->prev != head)) return -1; if (RB_WARN_ON(cpu_buffer, head->prev->next != head)) return -1; if (rb_check_list(cpu_buffer, head)) return -1; list_for_each_entry_safe(bpage, tmp, head, list) { if (RB_WARN_ON(cpu_buffer, bpage->list.next->prev != &bpage->list)) return -1; if (RB_WARN_ON(cpu_buffer, bpage->list.prev->next != &bpage->list)) return -1; if (rb_check_list(cpu_buffer, &bpage->list)) return -1; } rb_head_page_activate(cpu_buffer); return 0; } static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) { struct buffer_page *bpage, *tmp; LIST_HEAD(pages); unsigned i; WARN_ON(!nr_pages); for (i = 0; i < nr_pages; i++) { struct page *page; bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), GFP_KERNEL | __GFP_NORETRY, cpu_to_node(cpu_buffer->cpu)); if (!bpage) goto free_pages; rb_check_bpage(cpu_buffer, bpage); list_add(&bpage->list, &pages); page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), GFP_KERNEL | __GFP_NORETRY, 0); if (!page) goto free_pages; bpage->page = page_address(page); rb_init_page(bpage->page); } cpu_buffer->pages = pages.next; list_del(&pages); rb_check_pages(cpu_buffer); return 0; free_pages: list_for_each_entry_safe(bpage, tmp, &pages, list) { list_del_init(&bpage->list); free_buffer_page(bpage); } return -ENOMEM; } static struct ring_buffer_per_cpu * rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; struct buffer_page *bpage; struct page *page; int ret; cpu_buffer = kzalloc_node(ALIGN(sizeof(*cpu_buffer), cache_line_size()), GFP_KERNEL, cpu_to_node(cpu)); if (!cpu_buffer) return NULL; cpu_buffer->cpu = cpu; cpu_buffer->buffer = buffer; raw_spin_lock_init(&cpu_buffer->reader_lock); lockdep_set_class(&cpu_buffer->reader_lock, buffer->reader_lock_key); cpu_buffer->lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), GFP_KERNEL, cpu_to_node(cpu)); if (!bpage) goto fail_free_buffer; rb_check_bpage(cpu_buffer, bpage); cpu_buffer->reader_page = bpage; page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL, 0); if (!page) goto fail_free_reader; bpage->page = page_address(page); rb_init_page(bpage->page); INIT_LIST_HEAD(&cpu_buffer->reader_page->list); ret = rb_allocate_pages(cpu_buffer, buffer->pages); if (ret < 0) goto fail_free_reader; cpu_buffer->head_page = list_entry(cpu_buffer->pages, struct buffer_page, list); cpu_buffer->tail_page = cpu_buffer->commit_page = cpu_buffer->head_page; rb_head_page_activate(cpu_buffer); return cpu_buffer; fail_free_reader: free_buffer_page(cpu_buffer->reader_page); fail_free_buffer: kfree(cpu_buffer); return NULL; } static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer) { struct list_head *head = cpu_buffer->pages; struct buffer_page *bpage, *tmp; free_buffer_page(cpu_buffer->reader_page); rb_head_page_deactivate(cpu_buffer); if (head) { list_for_each_entry_safe(bpage, tmp, head, list) { list_del_init(&bpage->list); free_buffer_page(bpage); } bpage = list_entry(head, struct buffer_page, list); free_buffer_page(bpage); } kfree(cpu_buffer); } #ifdef CONFIG_HOTPLUG_CPU static int rb_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu); #endif struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key) { struct ring_buffer *buffer; int bsize; int cpu; buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()), GFP_KERNEL); if (!buffer) return NULL; if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL)) goto fail_free_buffer; buffer->pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); buffer->flags = flags; buffer->clock = trace_clock_local; buffer->reader_lock_key = key; if (buffer->pages < 2) buffer->pages = 2; #ifdef CONFIG_HOTPLUG_CPU get_online_cpus(); cpumask_copy(buffer->cpumask, cpu_online_mask); #else cpumask_copy(buffer->cpumask, cpu_possible_mask); #endif buffer->cpus = nr_cpu_ids; bsize = sizeof(void *) * nr_cpu_ids; buffer->buffers = kzalloc(ALIGN(bsize, cache_line_size()), GFP_KERNEL); if (!buffer->buffers) goto fail_free_cpumask; for_each_buffer_cpu(buffer, cpu) { buffer->buffers[cpu] = rb_allocate_cpu_buffer(buffer, cpu); if (!buffer->buffers[cpu]) goto fail_free_buffers; } #ifdef CONFIG_HOTPLUG_CPU buffer->cpu_notify.notifier_call = rb_cpu_notify; buffer->cpu_notify.priority = 0; register_cpu_notifier(&buffer->cpu_notify); #endif put_online_cpus(); mutex_init(&buffer->mutex); return buffer; fail_free_buffers: for_each_buffer_cpu(buffer, cpu) { if (buffer->buffers[cpu]) rb_free_cpu_buffer(buffer->buffers[cpu]); } kfree(buffer->buffers); fail_free_cpumask: free_cpumask_var(buffer->cpumask); put_online_cpus(); fail_free_buffer: kfree(buffer); return NULL; } EXPORT_SYMBOL_GPL(__ring_buffer_alloc); void ring_buffer_free(struct ring_buffer *buffer) { int cpu; get_online_cpus(); #ifdef CONFIG_HOTPLUG_CPU unregister_cpu_notifier(&buffer->cpu_notify); #endif for_each_buffer_cpu(buffer, cpu) rb_free_cpu_buffer(buffer->buffers[cpu]); put_online_cpus(); kfree(buffer->buffers); free_cpumask_var(buffer->cpumask); kfree(buffer); } EXPORT_SYMBOL_GPL(ring_buffer_free); void ring_buffer_set_clock(struct ring_buffer *buffer, u64 (*clock)(void)) { buffer->clock = clock; } static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer); static void rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned nr_pages) { struct buffer_page *bpage; struct list_head *p; unsigned i; raw_spin_lock_irq(&cpu_buffer->reader_lock); rb_head_page_deactivate(cpu_buffer); for (i = 0; i < nr_pages; i++) { if (RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages))) goto out; p = cpu_buffer->pages->next; bpage = list_entry(p, struct buffer_page, list); list_del_init(&bpage->list); free_buffer_page(bpage); } if (RB_WARN_ON(cpu_buffer, list_empty(cpu_buffer->pages))) goto out; rb_reset_cpu(cpu_buffer); rb_check_pages(cpu_buffer); out: raw_spin_unlock_irq(&cpu_buffer->reader_lock); } static void rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer, struct list_head *pages, unsigned nr_pages) { struct buffer_page *bpage; struct list_head *p; unsigned i; raw_spin_lock_irq(&cpu_buffer->reader_lock); rb_head_page_deactivate(cpu_buffer); for (i = 0; i < nr_pages; i++) { if (RB_WARN_ON(cpu_buffer, list_empty(pages))) goto out; p = pages->next; bpage = list_entry(p, struct buffer_page, list); list_del_init(&bpage->list); list_add_tail(&bpage->list, cpu_buffer->pages); } rb_reset_cpu(cpu_buffer); rb_check_pages(cpu_buffer); out: raw_spin_unlock_irq(&cpu_buffer->reader_lock); } int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size) { struct ring_buffer_per_cpu *cpu_buffer; unsigned nr_pages, rm_pages, new_pages; struct buffer_page *bpage, *tmp; unsigned long buffer_size; LIST_HEAD(pages); int i, cpu; if (!buffer) return size; size = DIV_ROUND_UP(size, BUF_PAGE_SIZE); size *= BUF_PAGE_SIZE; buffer_size = buffer->pages * BUF_PAGE_SIZE; if (size < BUF_PAGE_SIZE * 2) size = BUF_PAGE_SIZE * 2; if (size == buffer_size) return size; atomic_inc(&buffer->record_disabled); synchronize_sched(); mutex_lock(&buffer->mutex); get_online_cpus(); nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE); if (size < buffer_size) { if (RB_WARN_ON(buffer, nr_pages >= buffer->pages)) goto out_fail; rm_pages = buffer->pages - nr_pages; for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; rb_remove_pages(cpu_buffer, rm_pages); } goto out; } if (RB_WARN_ON(buffer, nr_pages <= buffer->pages)) goto out_fail; new_pages = nr_pages - buffer->pages; for_each_buffer_cpu(buffer, cpu) { for (i = 0; i < new_pages; i++) { struct page *page; bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()), GFP_KERNEL | __GFP_NORETRY, cpu_to_node(cpu)); if (!bpage) goto free_pages; list_add(&bpage->list, &pages); page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_NORETRY, 0); if (!page) goto free_pages; bpage->page = page_address(page); rb_init_page(bpage->page); } } for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; rb_insert_pages(cpu_buffer, &pages, new_pages); } if (RB_WARN_ON(buffer, !list_empty(&pages))) goto out_fail; out: buffer->pages = nr_pages; put_online_cpus(); mutex_unlock(&buffer->mutex); atomic_dec(&buffer->record_disabled); return size; free_pages: list_for_each_entry_safe(bpage, tmp, &pages, list) { list_del_init(&bpage->list); free_buffer_page(bpage); } put_online_cpus(); mutex_unlock(&buffer->mutex); atomic_dec(&buffer->record_disabled); return -ENOMEM; out_fail: put_online_cpus(); mutex_unlock(&buffer->mutex); atomic_dec(&buffer->record_disabled); return -1; } EXPORT_SYMBOL_GPL(ring_buffer_resize); void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val) { mutex_lock(&buffer->mutex); if (val) buffer->flags |= RB_FL_OVERWRITE; else buffer->flags &= ~RB_FL_OVERWRITE; mutex_unlock(&buffer->mutex); } EXPORT_SYMBOL_GPL(ring_buffer_change_overwrite); static inline void * __rb_data_page_index(struct buffer_data_page *bpage, unsigned index) { return bpage->data + index; } static inline void *__rb_page_index(struct buffer_page *bpage, unsigned index) { return bpage->page->data + index; } static inline struct ring_buffer_event * rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) { return __rb_page_index(cpu_buffer->reader_page, cpu_buffer->reader_page->read); } static inline struct ring_buffer_event * rb_iter_head_event(struct ring_buffer_iter *iter) { return __rb_page_index(iter->head_page, iter->head); } static inline unsigned long rb_page_write(struct buffer_page *bpage) { return local_read(&bpage->write) & RB_WRITE_MASK; } static inline unsigned rb_page_commit(struct buffer_page *bpage) { return local_read(&bpage->page->commit); } static inline unsigned long rb_page_entries(struct buffer_page *bpage) { return local_read(&bpage->entries) & RB_WRITE_MASK; } static inline unsigned rb_page_size(struct buffer_page *bpage) { return rb_page_commit(bpage); } static inline unsigned rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) { return rb_page_commit(cpu_buffer->commit_page); } static inline unsigned rb_event_index(struct ring_buffer_event *event) { unsigned long addr = (unsigned long)event; return (addr & ~PAGE_MASK) - BUF_PAGE_HDR_SIZE; } static inline int rb_event_is_commit(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { unsigned long addr = (unsigned long)event; unsigned long index; index = rb_event_index(event); addr &= PAGE_MASK; return cpu_buffer->commit_page->page == (void *)addr && rb_commit_index(cpu_buffer) == index; } static void rb_set_commit_to_write(struct ring_buffer_per_cpu *cpu_buffer) { unsigned long max_count; again: max_count = cpu_buffer->buffer->pages * 100; while (cpu_buffer->commit_page != cpu_buffer->tail_page) { if (RB_WARN_ON(cpu_buffer, !(--max_count))) return; if (RB_WARN_ON(cpu_buffer, rb_is_reader_page(cpu_buffer->tail_page))) return; local_set(&cpu_buffer->commit_page->page->commit, rb_page_write(cpu_buffer->commit_page)); rb_inc_page(cpu_buffer, &cpu_buffer->commit_page); cpu_buffer->write_stamp = cpu_buffer->commit_page->page->time_stamp; barrier(); } while (rb_commit_index(cpu_buffer) != rb_page_write(cpu_buffer->commit_page)) { local_set(&cpu_buffer->commit_page->page->commit, rb_page_write(cpu_buffer->commit_page)); RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->commit_page->page->commit) & ~RB_WRITE_MASK); barrier(); } barrier(); if (unlikely(cpu_buffer->commit_page != cpu_buffer->tail_page)) goto again; } static void rb_reset_reader_page(struct ring_buffer_per_cpu *cpu_buffer) { cpu_buffer->read_stamp = cpu_buffer->reader_page->page->time_stamp; cpu_buffer->reader_page->read = 0; } static void rb_inc_iter(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; if (iter->head_page == cpu_buffer->reader_page) iter->head_page = rb_set_head_page(cpu_buffer); else rb_inc_page(cpu_buffer, &iter->head_page); iter->read_stamp = iter->head_page->page->time_stamp; iter->head = 0; } static noinline struct ring_buffer_event * rb_add_time_stamp(struct ring_buffer_event *event, u64 delta) { event->type_len = RINGBUF_TYPE_TIME_EXTEND; if (rb_event_index(event)) { event->time_delta = delta & TS_MASK; event->array[0] = delta >> TS_SHIFT; } else { event->time_delta = 0; event->array[0] = 0; } return skip_time_extend(event); } /** * ring_buffer_update_event - update event type and data * @event: the even to update * @type: the type of event * @length: the size of the event field in the ring buffer * * Update the type and data fields of the event. The length * is the actual size that is written to the ring buffer, * and with this, we can determine what to place into the * data field. */ static void rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event, unsigned length, int add_timestamp, u64 delta) { if (unlikely(!rb_event_is_commit(cpu_buffer, event))) delta = 0; if (unlikely(add_timestamp)) { event = rb_add_time_stamp(event, delta); length -= RB_LEN_TIME_EXTEND; delta = 0; } event->time_delta = delta; length -= RB_EVNT_HDR_SIZE; if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { event->type_len = 0; event->array[0] = length; } else event->type_len = DIV_ROUND_UP(length, RB_ALIGNMENT); } static int rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *tail_page, struct buffer_page *next_page) { struct buffer_page *new_head; int entries; int type; int ret; entries = rb_page_entries(next_page); type = rb_head_page_set_update(cpu_buffer, next_page, tail_page, RB_PAGE_HEAD); switch (type) { case RB_PAGE_HEAD: local_add(entries, &cpu_buffer->overrun); local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); break; case RB_PAGE_UPDATE: break; case RB_PAGE_NORMAL: return 1; case RB_PAGE_MOVED: return 1; default: RB_WARN_ON(cpu_buffer, 1); return -1; } new_head = next_page; rb_inc_page(cpu_buffer, &new_head); ret = rb_head_page_set_head(cpu_buffer, new_head, next_page, RB_PAGE_NORMAL); switch (ret) { case RB_PAGE_HEAD: case RB_PAGE_NORMAL: break; default: RB_WARN_ON(cpu_buffer, 1); return -1; } if (ret == RB_PAGE_NORMAL) { if (cpu_buffer->tail_page != tail_page && cpu_buffer->tail_page != next_page) rb_head_page_set_normal(cpu_buffer, new_head, next_page, RB_PAGE_HEAD); } if (type == RB_PAGE_HEAD) { ret = rb_head_page_set_normal(cpu_buffer, next_page, tail_page, RB_PAGE_UPDATE); if (RB_WARN_ON(cpu_buffer, ret != RB_PAGE_UPDATE)) return -1; } return 0; } static unsigned rb_calculate_event_length(unsigned length) { struct ring_buffer_event event; if (!length) length = 1; if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) length += sizeof(event.array[0]); length += RB_EVNT_HDR_SIZE; length = ALIGN(length, RB_ARCH_ALIGNMENT); return length; } static inline void rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, struct buffer_page *tail_page, unsigned long tail, unsigned long length) { struct ring_buffer_event *event; if (tail >= BUF_PAGE_SIZE) { if (tail == BUF_PAGE_SIZE) tail_page->real_end = 0; local_sub(length, &tail_page->write); return; } event = __rb_page_index(tail_page, tail); kmemcheck_annotate_bitfield(event, bitfield); local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); tail_page->real_end = tail; if (tail > (BUF_PAGE_SIZE - RB_EVNT_MIN_SIZE)) { rb_event_set_padding(event); local_sub(length, &tail_page->write); return; } event->array[0] = (BUF_PAGE_SIZE - tail) - RB_EVNT_HDR_SIZE; event->type_len = RINGBUF_TYPE_PADDING; event->time_delta = 1; length = (tail + length) - BUF_PAGE_SIZE; local_sub(length, &tail_page->write); } static noinline struct ring_buffer_event * rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer, unsigned long length, unsigned long tail, struct buffer_page *tail_page, u64 ts) { struct buffer_page *commit_page = cpu_buffer->commit_page; struct ring_buffer *buffer = cpu_buffer->buffer; struct buffer_page *next_page; int ret; next_page = tail_page; rb_inc_page(cpu_buffer, &next_page); if (unlikely(next_page == commit_page)) { local_inc(&cpu_buffer->commit_overrun); goto out_reset; } if (rb_is_head_page(cpu_buffer, next_page, &tail_page->list)) { if (!rb_is_reader_page(cpu_buffer->commit_page)) { if (!(buffer->flags & RB_FL_OVERWRITE)) goto out_reset; ret = rb_handle_head_page(cpu_buffer, tail_page, next_page); if (ret < 0) goto out_reset; if (ret) goto out_again; } else { if (unlikely((cpu_buffer->commit_page != cpu_buffer->tail_page) && (cpu_buffer->commit_page == cpu_buffer->reader_page))) { local_inc(&cpu_buffer->commit_overrun); goto out_reset; } } } ret = rb_tail_page_update(cpu_buffer, tail_page, next_page); if (ret) { ts = rb_time_stamp(buffer); next_page->page->time_stamp = ts; } out_again: rb_reset_tail(cpu_buffer, tail_page, tail, length); return ERR_PTR(-EAGAIN); out_reset: rb_reset_tail(cpu_buffer, tail_page, tail, length); return NULL; } static struct ring_buffer_event * __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer, unsigned long length, u64 ts, u64 delta, int add_timestamp) { struct buffer_page *tail_page; struct ring_buffer_event *event; unsigned long tail, write; if (unlikely(add_timestamp)) length += RB_LEN_TIME_EXTEND; tail_page = cpu_buffer->tail_page; write = local_add_return(length, &tail_page->write); write &= RB_WRITE_MASK; tail = write - length; /* * If this is the first commit on the page, then it has the same * timestamp as the page itself. */ if (!tail) delta = 0; /* See if we shot pass the end of this buffer page */ if (unlikely(write > BUF_PAGE_SIZE)) return rb_move_tail(cpu_buffer, length, tail, tail_page, ts); event = __rb_page_index(tail_page, tail); kmemcheck_annotate_bitfield(event, bitfield); rb_update_event(cpu_buffer, event, length, add_timestamp, delta); local_inc(&tail_page->entries); if (!tail) tail_page->page->time_stamp = ts; local_add(length, &cpu_buffer->entries_bytes); return event; } static inline int rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { unsigned long new_index, old_index; struct buffer_page *bpage; unsigned long index; unsigned long addr; new_index = rb_event_index(event); old_index = new_index + rb_event_ts_length(event); addr = (unsigned long)event; addr &= PAGE_MASK; bpage = cpu_buffer->tail_page; if (bpage->page == (void *)addr && rb_page_write(bpage) == old_index) { unsigned long write_mask = local_read(&bpage->write) & ~RB_WRITE_MASK; unsigned long event_length = rb_event_length(event); old_index += write_mask; new_index += write_mask; index = local_cmpxchg(&bpage->write, old_index, new_index); if (index == old_index) { local_sub(event_length, &cpu_buffer->entries_bytes); return 1; } } return 0; } static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer) { local_inc(&cpu_buffer->committing); local_inc(&cpu_buffer->commits); } static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer) { unsigned long commits; if (RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing))) return; again: commits = local_read(&cpu_buffer->commits); barrier(); if (local_read(&cpu_buffer->committing) == 1) rb_set_commit_to_write(cpu_buffer); local_dec(&cpu_buffer->committing); barrier(); if (unlikely(local_read(&cpu_buffer->commits) != commits) && !local_read(&cpu_buffer->committing)) { local_inc(&cpu_buffer->committing); goto again; } } static struct ring_buffer_event * rb_reserve_next_event(struct ring_buffer *buffer, struct ring_buffer_per_cpu *cpu_buffer, unsigned long length) { struct ring_buffer_event *event; u64 ts, delta; int nr_loops = 0; int add_timestamp; u64 diff; rb_start_commit(cpu_buffer); #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP barrier(); if (unlikely(ACCESS_ONCE(cpu_buffer->buffer) != buffer)) { local_dec(&cpu_buffer->committing); local_dec(&cpu_buffer->commits); return NULL; } #endif length = rb_calculate_event_length(length); again: add_timestamp = 0; delta = 0; if (RB_WARN_ON(cpu_buffer, ++nr_loops > 1000)) goto out_fail; ts = rb_time_stamp(cpu_buffer->buffer); diff = ts - cpu_buffer->write_stamp; barrier(); if (likely(ts >= cpu_buffer->write_stamp)) { delta = diff; if (unlikely(test_time_stamp(delta))) { int local_clock_stable = 1; #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK local_clock_stable = sched_clock_stable; #endif WARN_ONCE(delta > (1ULL << 59), KERN_WARNING "Delta way too big! %llu ts=%llu write stamp = %llu\n%s", (unsigned long long)delta, (unsigned long long)ts, (unsigned long long)cpu_buffer->write_stamp, local_clock_stable ? "" : "If you just came from a suspend/resume,\n" "please switch to the trace global clock:\n" " echo global > /sys/kernel/debug/tracing/trace_clock\n"); add_timestamp = 1; } } event = __rb_reserve_next(cpu_buffer, length, ts, delta, add_timestamp); if (unlikely(PTR_ERR(event) == -EAGAIN)) goto again; if (!event) goto out_fail; return event; out_fail: rb_end_commit(cpu_buffer); return NULL; } #ifdef CONFIG_TRACING #define TRACE_RECURSIVE_DEPTH 16 static noinline void trace_recursive_fail(void) { tracing_off_permanent(); printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:" "HC[%lu]:SC[%lu]:NMI[%lu]\n", trace_recursion_buffer(), hardirq_count() >> HARDIRQ_SHIFT, softirq_count() >> SOFTIRQ_SHIFT, in_nmi()); WARN_ON_ONCE(1); } static inline int trace_recursive_lock(void) { trace_recursion_inc(); if (likely(trace_recursion_buffer() < TRACE_RECURSIVE_DEPTH)) return 0; trace_recursive_fail(); return -1; } static inline void trace_recursive_unlock(void) { WARN_ON_ONCE(!trace_recursion_buffer()); trace_recursion_dec(); } #else #define trace_recursive_lock() (0) #define trace_recursive_unlock() do { } while (0) #endif struct ring_buffer_event * ring_buffer_lock_reserve(struct ring_buffer *buffer, unsigned long length) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; int cpu; if (ring_buffer_flags != RB_BUFFERS_ON) return NULL; preempt_disable_notrace(); if (atomic_read(&buffer->record_disabled)) goto out_nocheck; if (trace_recursive_lock()) goto out_nocheck; cpu = raw_smp_processor_id(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) goto out; cpu_buffer = buffer->buffers[cpu]; if (atomic_read(&cpu_buffer->record_disabled)) goto out; if (length > BUF_MAX_DATA_SIZE) goto out; event = rb_reserve_next_event(buffer, cpu_buffer, length); if (!event) goto out; return event; out: trace_recursive_unlock(); out_nocheck: preempt_enable_notrace(); return NULL; } EXPORT_SYMBOL_GPL(ring_buffer_lock_reserve); static void rb_update_write_stamp(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { u64 delta; if (rb_event_is_commit(cpu_buffer, event)) { if (!rb_event_index(event)) cpu_buffer->write_stamp = cpu_buffer->commit_page->page->time_stamp; else if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) { delta = event->array[0]; delta <<= TS_SHIFT; delta += event->time_delta; cpu_buffer->write_stamp += delta; } else cpu_buffer->write_stamp += event->time_delta; } } static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { local_inc(&cpu_buffer->entries); rb_update_write_stamp(cpu_buffer, event); rb_end_commit(cpu_buffer); } int ring_buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event) { struct ring_buffer_per_cpu *cpu_buffer; int cpu = raw_smp_processor_id(); cpu_buffer = buffer->buffers[cpu]; rb_commit(cpu_buffer, event); trace_recursive_unlock(); preempt_enable_notrace(); return 0; } EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit); static inline void rb_event_discard(struct ring_buffer_event *event) { if (event->type_len == RINGBUF_TYPE_TIME_EXTEND) event = skip_time_extend(event); event->array[0] = rb_event_data_length(event) - RB_EVNT_HDR_SIZE; event->type_len = RINGBUF_TYPE_PADDING; if (!event->time_delta) event->time_delta = 1; } static inline void rb_decrement_entry(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { unsigned long addr = (unsigned long)event; struct buffer_page *bpage = cpu_buffer->commit_page; struct buffer_page *start; addr &= PAGE_MASK; if (likely(bpage->page == (void *)addr)) { local_dec(&bpage->entries); return; } rb_inc_page(cpu_buffer, &bpage); start = bpage; do { if (bpage->page == (void *)addr) { local_dec(&bpage->entries); return; } rb_inc_page(cpu_buffer, &bpage); } while (bpage != start); RB_WARN_ON(cpu_buffer, 1); } void ring_buffer_discard_commit(struct ring_buffer *buffer, struct ring_buffer_event *event) { struct ring_buffer_per_cpu *cpu_buffer; int cpu; rb_event_discard(event); cpu = smp_processor_id(); cpu_buffer = buffer->buffers[cpu]; RB_WARN_ON(buffer, !local_read(&cpu_buffer->committing)); rb_decrement_entry(cpu_buffer, event); if (rb_try_to_discard(cpu_buffer, event)) goto out; rb_update_write_stamp(cpu_buffer, event); out: rb_end_commit(cpu_buffer); trace_recursive_unlock(); preempt_enable_notrace(); } EXPORT_SYMBOL_GPL(ring_buffer_discard_commit); /** * ring_buffer_write - write data to the buffer without reserving * @buffer: The ring buffer to write to. * @length: The length of the data being written (excluding the event header) * @data: The data to write to the buffer. * * This is like ring_buffer_lock_reserve and ring_buffer_unlock_commit as * one function. If you already have the data to write to the buffer, it * may be easier to simply call this function. * * Note, like ring_buffer_lock_reserve, the length is the length of the data * and not the length of the event which would hold the header. */ int ring_buffer_write(struct ring_buffer *buffer, unsigned long length, void *data) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; void *body; int ret = -EBUSY; int cpu; if (ring_buffer_flags != RB_BUFFERS_ON) return -EBUSY; preempt_disable_notrace(); if (atomic_read(&buffer->record_disabled)) goto out; cpu = raw_smp_processor_id(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) goto out; cpu_buffer = buffer->buffers[cpu]; if (atomic_read(&cpu_buffer->record_disabled)) goto out; if (length > BUF_MAX_DATA_SIZE) goto out; event = rb_reserve_next_event(buffer, cpu_buffer, length); if (!event) goto out; body = rb_event_data(event); memcpy(body, data, length); rb_commit(cpu_buffer, event); ret = 0; out: preempt_enable_notrace(); return ret; } EXPORT_SYMBOL_GPL(ring_buffer_write); static int rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *reader = cpu_buffer->reader_page; struct buffer_page *head = rb_set_head_page(cpu_buffer); struct buffer_page *commit = cpu_buffer->commit_page; if (unlikely(!head)) return 1; return reader->read == rb_page_commit(reader) && (commit == reader || (commit == head && head->read == rb_page_commit(commit))); } void ring_buffer_record_disable(struct ring_buffer *buffer) { atomic_inc(&buffer->record_disabled); } EXPORT_SYMBOL_GPL(ring_buffer_record_disable); void ring_buffer_record_enable(struct ring_buffer *buffer) { atomic_dec(&buffer->record_disabled); } EXPORT_SYMBOL_GPL(ring_buffer_record_enable); void ring_buffer_record_off(struct ring_buffer *buffer) { unsigned int rd; unsigned int new_rd; do { rd = atomic_read(&buffer->record_disabled); new_rd = rd | RB_BUFFER_OFF; } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); } EXPORT_SYMBOL_GPL(ring_buffer_record_off); void ring_buffer_record_on(struct ring_buffer *buffer) { unsigned int rd; unsigned int new_rd; do { rd = atomic_read(&buffer->record_disabled); new_rd = rd & ~RB_BUFFER_OFF; } while (atomic_cmpxchg(&buffer->record_disabled, rd, new_rd) != rd); } EXPORT_SYMBOL_GPL(ring_buffer_record_on); int ring_buffer_record_is_on(struct ring_buffer *buffer) { return !atomic_read(&buffer->record_disabled); } void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return; cpu_buffer = buffer->buffers[cpu]; atomic_inc(&cpu_buffer->record_disabled); } EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu); void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return; cpu_buffer = buffer->buffers[cpu]; atomic_dec(&cpu_buffer->record_disabled); } EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu); /* * The total entries in the ring buffer is the running counter * of entries entered into the ring buffer, minus the sum of * the entries read from the ring buffer and the number of * entries that were overwritten. */ static inline unsigned long rb_num_of_entries(struct ring_buffer_per_cpu *cpu_buffer) { return local_read(&cpu_buffer->entries) - (local_read(&cpu_buffer->overrun) + cpu_buffer->read); } unsigned long ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu) { unsigned long flags; struct ring_buffer_per_cpu *cpu_buffer; struct buffer_page *bpage; unsigned long ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; cpu_buffer = buffer->buffers[cpu]; raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); if (cpu_buffer->tail_page == cpu_buffer->reader_page) bpage = cpu_buffer->reader_page; else bpage = rb_set_head_page(cpu_buffer); ret = bpage->page->time_stamp; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); return ret; } EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; cpu_buffer = buffer->buffers[cpu]; ret = local_read(&cpu_buffer->entries_bytes) - cpu_buffer->read_bytes; return ret; } EXPORT_SYMBOL_GPL(ring_buffer_bytes_cpu); unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; cpu_buffer = buffer->buffers[cpu]; return rb_num_of_entries(cpu_buffer); } EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu); unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; cpu_buffer = buffer->buffers[cpu]; ret = local_read(&cpu_buffer->overrun); return ret; } EXPORT_SYMBOL_GPL(ring_buffer_overrun_cpu); unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; cpu_buffer = buffer->buffers[cpu]; ret = local_read(&cpu_buffer->commit_overrun); return ret; } EXPORT_SYMBOL_GPL(ring_buffer_commit_overrun_cpu); unsigned long ring_buffer_entries(struct ring_buffer *buffer) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long entries = 0; int cpu; for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; entries += rb_num_of_entries(cpu_buffer); } return entries; } EXPORT_SYMBOL_GPL(ring_buffer_entries); unsigned long ring_buffer_overruns(struct ring_buffer *buffer) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long overruns = 0; int cpu; for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; overruns += local_read(&cpu_buffer->overrun); } return overruns; } EXPORT_SYMBOL_GPL(ring_buffer_overruns); static void rb_iter_reset(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; if (list_empty(&cpu_buffer->reader_page->list)) { iter->head_page = rb_set_head_page(cpu_buffer); if (unlikely(!iter->head_page)) return; iter->head = iter->head_page->read; } else { iter->head_page = cpu_buffer->reader_page; iter->head = cpu_buffer->reader_page->read; } if (iter->head) iter->read_stamp = cpu_buffer->read_stamp; else iter->read_stamp = iter->head_page->page->time_stamp; iter->cache_reader_page = cpu_buffer->reader_page; iter->cache_read = cpu_buffer->read; } void ring_buffer_iter_reset(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; if (!iter) return; cpu_buffer = iter->cpu_buffer; raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_iter_reset(iter); raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } EXPORT_SYMBOL_GPL(ring_buffer_iter_reset); int ring_buffer_iter_empty(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer; cpu_buffer = iter->cpu_buffer; return iter->head_page == cpu_buffer->commit_page && iter->head == rb_commit_index(cpu_buffer); } EXPORT_SYMBOL_GPL(ring_buffer_iter_empty); static void rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) { u64 delta; switch (event->type_len) { case RINGBUF_TYPE_PADDING: return; case RINGBUF_TYPE_TIME_EXTEND: delta = event->array[0]; delta <<= TS_SHIFT; delta += event->time_delta; cpu_buffer->read_stamp += delta; return; case RINGBUF_TYPE_TIME_STAMP: return; case RINGBUF_TYPE_DATA: cpu_buffer->read_stamp += event->time_delta; return; default: BUG(); } return; } static void rb_update_iter_read_stamp(struct ring_buffer_iter *iter, struct ring_buffer_event *event) { u64 delta; switch (event->type_len) { case RINGBUF_TYPE_PADDING: return; case RINGBUF_TYPE_TIME_EXTEND: delta = event->array[0]; delta <<= TS_SHIFT; delta += event->time_delta; iter->read_stamp += delta; return; case RINGBUF_TYPE_TIME_STAMP: return; case RINGBUF_TYPE_DATA: iter->read_stamp += event->time_delta; return; default: BUG(); } return; } static struct buffer_page * rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *reader = NULL; unsigned long overwrite; unsigned long flags; int nr_loops = 0; int ret; local_irq_save(flags); arch_spin_lock(&cpu_buffer->lock); again: if (RB_WARN_ON(cpu_buffer, ++nr_loops > 3)) { reader = NULL; goto out; } reader = cpu_buffer->reader_page; if (cpu_buffer->reader_page->read < rb_page_size(reader)) goto out; if (RB_WARN_ON(cpu_buffer, cpu_buffer->reader_page->read > rb_page_size(reader))) goto out; reader = NULL; if (cpu_buffer->commit_page == cpu_buffer->reader_page) goto out; local_set(&cpu_buffer->reader_page->write, 0); local_set(&cpu_buffer->reader_page->entries, 0); local_set(&cpu_buffer->reader_page->page->commit, 0); cpu_buffer->reader_page->real_end = 0; spin: reader = rb_set_head_page(cpu_buffer); cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); cpu_buffer->reader_page->list.prev = reader->list.prev; cpu_buffer->pages = reader->list.prev; rb_set_list_to_head(cpu_buffer, &cpu_buffer->reader_page->list); smp_mb(); overwrite = local_read(&(cpu_buffer->overrun)); ret = rb_head_page_replace(reader, cpu_buffer->reader_page); if (!ret) goto spin; rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list; rb_inc_page(cpu_buffer, &cpu_buffer->head_page); cpu_buffer->reader_page = reader; rb_reset_reader_page(cpu_buffer); if (overwrite != cpu_buffer->last_overrun) { cpu_buffer->lost_events = overwrite - cpu_buffer->last_overrun; cpu_buffer->last_overrun = overwrite; } goto again; out: arch_spin_unlock(&cpu_buffer->lock); local_irq_restore(flags); return reader; } static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) { struct ring_buffer_event *event; struct buffer_page *reader; unsigned length; reader = rb_get_reader_page(cpu_buffer); if (RB_WARN_ON(cpu_buffer, !reader)) return; event = rb_reader_event(cpu_buffer); if (event->type_len <= RINGBUF_TYPE_DATA_TYPE_LEN_MAX) cpu_buffer->read++; rb_update_read_stamp(cpu_buffer, event); length = rb_event_length(event); cpu_buffer->reader_page->read += length; } static void rb_advance_iter(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; unsigned length; cpu_buffer = iter->cpu_buffer; if (iter->head >= rb_page_size(iter->head_page)) { if (iter->head_page == cpu_buffer->commit_page) return; rb_inc_iter(iter); return; } event = rb_iter_head_event(iter); length = rb_event_length(event); if (RB_WARN_ON(cpu_buffer, (iter->head_page == cpu_buffer->commit_page) && (iter->head + length > rb_commit_index(cpu_buffer)))) return; rb_update_iter_read_stamp(iter, event); iter->head += length; if ((iter->head >= rb_page_size(iter->head_page)) && (iter->head_page != cpu_buffer->commit_page)) rb_advance_iter(iter); } static int rb_lost_events(struct ring_buffer_per_cpu *cpu_buffer) { return cpu_buffer->lost_events; } static struct ring_buffer_event * rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, unsigned long *lost_events) { struct ring_buffer_event *event; struct buffer_page *reader; int nr_loops = 0; again: if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) return NULL; reader = rb_get_reader_page(cpu_buffer); if (!reader) return NULL; event = rb_reader_event(cpu_buffer); switch (event->type_len) { case RINGBUF_TYPE_PADDING: if (rb_null_event(event)) RB_WARN_ON(cpu_buffer, 1); return event; case RINGBUF_TYPE_TIME_EXTEND: rb_advance_reader(cpu_buffer); goto again; case RINGBUF_TYPE_TIME_STAMP: rb_advance_reader(cpu_buffer); goto again; case RINGBUF_TYPE_DATA: if (ts) { *ts = cpu_buffer->read_stamp + event->time_delta; ring_buffer_normalize_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu, ts); } if (lost_events) *lost_events = rb_lost_events(cpu_buffer); return event; default: BUG(); } return NULL; } EXPORT_SYMBOL_GPL(ring_buffer_peek); static struct ring_buffer_event * rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) { struct ring_buffer *buffer; struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event; int nr_loops = 0; cpu_buffer = iter->cpu_buffer; buffer = cpu_buffer->buffer; if (unlikely(iter->cache_read != cpu_buffer->read || iter->cache_reader_page != cpu_buffer->reader_page)) rb_iter_reset(iter); again: if (ring_buffer_iter_empty(iter)) return NULL; if (RB_WARN_ON(cpu_buffer, ++nr_loops > 2)) return NULL; if (rb_per_cpu_empty(cpu_buffer)) return NULL; if (iter->head >= local_read(&iter->head_page->page->commit)) { rb_inc_iter(iter); goto again; } event = rb_iter_head_event(iter); switch (event->type_len) { case RINGBUF_TYPE_PADDING: if (rb_null_event(event)) { rb_inc_iter(iter); goto again; } rb_advance_iter(iter); return event; case RINGBUF_TYPE_TIME_EXTEND: rb_advance_iter(iter); goto again; case RINGBUF_TYPE_TIME_STAMP: rb_advance_iter(iter); goto again; case RINGBUF_TYPE_DATA: if (ts) { *ts = iter->read_stamp + event->time_delta; ring_buffer_normalize_time_stamp(buffer, cpu_buffer->cpu, ts); } return event; default: BUG(); } return NULL; } EXPORT_SYMBOL_GPL(ring_buffer_iter_peek); static inline int rb_ok_to_lock(void) { if (likely(!in_nmi())) return 1; tracing_off_permanent(); return 0; } struct ring_buffer_event * ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts, unsigned long *lost_events) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; struct ring_buffer_event *event; unsigned long flags; int dolock; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return NULL; dolock = rb_ok_to_lock(); again: local_irq_save(flags); if (dolock) raw_spin_lock(&cpu_buffer->reader_lock); event = rb_buffer_peek(cpu_buffer, ts, lost_events); if (event && event->type_len == RINGBUF_TYPE_PADDING) rb_advance_reader(cpu_buffer); if (dolock) raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); if (event && event->type_len == RINGBUF_TYPE_PADDING) goto again; return event; } struct ring_buffer_event * ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; struct ring_buffer_event *event; unsigned long flags; again: raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); event = rb_iter_peek(iter, ts); raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); if (event && event->type_len == RINGBUF_TYPE_PADDING) goto again; return event; } struct ring_buffer_event * ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts, unsigned long *lost_events) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_event *event = NULL; unsigned long flags; int dolock; dolock = rb_ok_to_lock(); again: preempt_disable(); if (!cpumask_test_cpu(cpu, buffer->cpumask)) goto out; cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) raw_spin_lock(&cpu_buffer->reader_lock); event = rb_buffer_peek(cpu_buffer, ts, lost_events); if (event) { cpu_buffer->lost_events = 0; rb_advance_reader(cpu_buffer); } if (dolock) raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); out: preempt_enable(); if (event && event->type_len == RINGBUF_TYPE_PADDING) goto again; return event; } EXPORT_SYMBOL_GPL(ring_buffer_consume); struct ring_buffer_iter * ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_iter *iter; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return NULL; iter = kmalloc(sizeof(*iter), GFP_KERNEL); if (!iter) return NULL; cpu_buffer = buffer->buffers[cpu]; iter->cpu_buffer = cpu_buffer; atomic_inc(&cpu_buffer->record_disabled); return iter; } EXPORT_SYMBOL_GPL(ring_buffer_read_prepare); void ring_buffer_read_prepare_sync(void) { synchronize_sched(); } EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync); void ring_buffer_read_start(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; if (!iter) return; cpu_buffer = iter->cpu_buffer; raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); arch_spin_lock(&cpu_buffer->lock); rb_iter_reset(iter); arch_spin_unlock(&cpu_buffer->lock); raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } EXPORT_SYMBOL_GPL(ring_buffer_read_start); void ring_buffer_read_finish(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; atomic_dec(&cpu_buffer->record_disabled); kfree(iter); } EXPORT_SYMBOL_GPL(ring_buffer_read_finish); struct ring_buffer_event * ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts) { struct ring_buffer_event *event; struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; unsigned long flags; raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); again: event = rb_iter_peek(iter, ts); if (!event) goto out; if (event->type_len == RINGBUF_TYPE_PADDING) goto again; rb_advance_iter(iter); out: raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); return event; } EXPORT_SYMBOL_GPL(ring_buffer_read); unsigned long ring_buffer_size(struct ring_buffer *buffer) { return BUF_PAGE_SIZE * buffer->pages; } EXPORT_SYMBOL_GPL(ring_buffer_size); static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) { rb_head_page_deactivate(cpu_buffer); cpu_buffer->head_page = list_entry(cpu_buffer->pages, struct buffer_page, list); local_set(&cpu_buffer->head_page->write, 0); local_set(&cpu_buffer->head_page->entries, 0); local_set(&cpu_buffer->head_page->page->commit, 0); cpu_buffer->head_page->read = 0; cpu_buffer->tail_page = cpu_buffer->head_page; cpu_buffer->commit_page = cpu_buffer->head_page; INIT_LIST_HEAD(&cpu_buffer->reader_page->list); local_set(&cpu_buffer->reader_page->write, 0); local_set(&cpu_buffer->reader_page->entries, 0); local_set(&cpu_buffer->reader_page->page->commit, 0); cpu_buffer->reader_page->read = 0; local_set(&cpu_buffer->commit_overrun, 0); local_set(&cpu_buffer->entries_bytes, 0); local_set(&cpu_buffer->overrun, 0); local_set(&cpu_buffer->entries, 0); local_set(&cpu_buffer->committing, 0); local_set(&cpu_buffer->commits, 0); cpu_buffer->read = 0; cpu_buffer->read_bytes = 0; cpu_buffer->write_stamp = 0; cpu_buffer->read_stamp = 0; cpu_buffer->lost_events = 0; cpu_buffer->last_overrun = 0; rb_head_page_activate(cpu_buffer); } void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; unsigned long flags; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return; atomic_inc(&cpu_buffer->record_disabled); raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); if (RB_WARN_ON(cpu_buffer, local_read(&cpu_buffer->committing))) goto out; arch_spin_lock(&cpu_buffer->lock); rb_reset_cpu(cpu_buffer); arch_spin_unlock(&cpu_buffer->lock); out: raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); atomic_dec(&cpu_buffer->record_disabled); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); void ring_buffer_reset(struct ring_buffer *buffer) { int cpu; for_each_buffer_cpu(buffer, cpu) ring_buffer_reset_cpu(buffer, cpu); } EXPORT_SYMBOL_GPL(ring_buffer_reset); int ring_buffer_empty(struct ring_buffer *buffer) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; int dolock; int cpu; int ret; dolock = rb_ok_to_lock(); for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) raw_spin_lock(&cpu_buffer->reader_lock); ret = rb_per_cpu_empty(cpu_buffer); if (dolock) raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); if (!ret) return 0; } return 1; } EXPORT_SYMBOL_GPL(ring_buffer_empty); int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; unsigned long flags; int dolock; int ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 1; dolock = rb_ok_to_lock(); cpu_buffer = buffer->buffers[cpu]; local_irq_save(flags); if (dolock) raw_spin_lock(&cpu_buffer->reader_lock); ret = rb_per_cpu_empty(cpu_buffer); if (dolock) raw_spin_unlock(&cpu_buffer->reader_lock); local_irq_restore(flags); return ret; } EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP int ring_buffer_swap_cpu(struct ring_buffer *buffer_a, struct ring_buffer *buffer_b, int cpu) { struct ring_buffer_per_cpu *cpu_buffer_a; struct ring_buffer_per_cpu *cpu_buffer_b; int ret = -EINVAL; if (!cpumask_test_cpu(cpu, buffer_a->cpumask) || !cpumask_test_cpu(cpu, buffer_b->cpumask)) goto out; if (buffer_a->pages != buffer_b->pages) goto out; ret = -EAGAIN; if (ring_buffer_flags != RB_BUFFERS_ON) goto out; if (atomic_read(&buffer_a->record_disabled)) goto out; if (atomic_read(&buffer_b->record_disabled)) goto out; cpu_buffer_a = buffer_a->buffers[cpu]; cpu_buffer_b = buffer_b->buffers[cpu]; if (atomic_read(&cpu_buffer_a->record_disabled)) goto out; if (atomic_read(&cpu_buffer_b->record_disabled)) goto out; atomic_inc(&cpu_buffer_a->record_disabled); atomic_inc(&cpu_buffer_b->record_disabled); ret = -EBUSY; if (local_read(&cpu_buffer_a->committing)) goto out_dec; if (local_read(&cpu_buffer_b->committing)) goto out_dec; buffer_a->buffers[cpu] = cpu_buffer_b; buffer_b->buffers[cpu] = cpu_buffer_a; cpu_buffer_b->buffer = buffer_a; cpu_buffer_a->buffer = buffer_b; ret = 0; out_dec: atomic_dec(&cpu_buffer_a->record_disabled); atomic_dec(&cpu_buffer_b->record_disabled); out: return ret; } EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu); #endif void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu) { struct buffer_data_page *bpage; struct page *page; page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_NORETRY, 0); if (!page) return NULL; bpage = page_address(page); rb_init_page(bpage); return bpage; } EXPORT_SYMBOL_GPL(ring_buffer_alloc_read_page); void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data) { free_page((unsigned long)data); } EXPORT_SYMBOL_GPL(ring_buffer_free_read_page); int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page, size_t len, int cpu, int full) { struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu]; struct ring_buffer_event *event; struct buffer_data_page *bpage; struct buffer_page *reader; unsigned long missed_events; unsigned long flags; unsigned int commit; unsigned int read; u64 save_timestamp; int ret = -1; if (!cpumask_test_cpu(cpu, buffer->cpumask)) goto out; if (len <= BUF_PAGE_HDR_SIZE) goto out; len -= BUF_PAGE_HDR_SIZE; if (!data_page) goto out; bpage = *data_page; if (!bpage) goto out; raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); reader = rb_get_reader_page(cpu_buffer); if (!reader) goto out_unlock; event = rb_reader_event(cpu_buffer); read = reader->read; commit = rb_page_commit(reader); missed_events = cpu_buffer->lost_events; if (read || (len < (commit - read)) || cpu_buffer->reader_page == cpu_buffer->commit_page) { struct buffer_data_page *rpage = cpu_buffer->reader_page->page; unsigned int rpos = read; unsigned int pos = 0; unsigned int size; if (full) goto out_unlock; if (len > (commit - read)) len = (commit - read); size = rb_event_ts_length(event); if (len < size) goto out_unlock; save_timestamp = cpu_buffer->read_stamp; do { size = rb_event_length(event); memcpy(bpage->data + pos, rpage->data + rpos, size); len -= size; rb_advance_reader(cpu_buffer); rpos = reader->read; pos += size; if (rpos >= commit) break; event = rb_reader_event(cpu_buffer); size = rb_event_ts_length(event); } while (len >= size); local_set(&bpage->commit, pos); bpage->time_stamp = save_timestamp; read = 0; } else { cpu_buffer->read += rb_page_entries(reader); cpu_buffer->read_bytes += BUF_PAGE_SIZE; rb_init_page(bpage); bpage = reader->page; reader->page = *data_page; local_set(&reader->write, 0); local_set(&reader->entries, 0); reader->read = 0; *data_page = bpage; if (reader->real_end) local_set(&bpage->commit, reader->real_end); } ret = read; cpu_buffer->lost_events = 0; commit = local_read(&bpage->commit); if (missed_events) { if (BUF_PAGE_SIZE - commit >= sizeof(missed_events)) { memcpy(&bpage->data[commit], &missed_events, sizeof(missed_events)); local_add(RB_MISSED_STORED, &bpage->commit); commit += sizeof(missed_events); } local_add(RB_MISSED_EVENTS, &bpage->commit); } if (commit < BUF_PAGE_SIZE) memset(&bpage->data[commit], 0, BUF_PAGE_SIZE - commit); out_unlock: raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); out: return ret; } EXPORT_SYMBOL_GPL(ring_buffer_read_page); #ifdef CONFIG_HOTPLUG_CPU static int rb_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { struct ring_buffer *buffer = container_of(self, struct ring_buffer, cpu_notify); long cpu = (long)hcpu; switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: if (cpumask_test_cpu(cpu, buffer->cpumask)) return NOTIFY_OK; buffer->buffers[cpu] = rb_allocate_cpu_buffer(buffer, cpu); if (!buffer->buffers[cpu]) { WARN(1, "failed to allocate ring buffer on CPU %ld\n", cpu); return NOTIFY_OK; } smp_wmb(); cpumask_set_cpu(cpu, buffer->cpumask); break; case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: break; default: break; } return NOTIFY_OK; } #endif