diff options
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 45 |
1 files changed, 19 insertions, 26 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index de061dd47313..78502d4c7214 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -523,6 +523,8 @@ struct ring_buffer_per_cpu { rb_time_t before_stamp; u64 event_stamp[MAX_NEST]; u64 read_stamp; + /* pages removed since last reset */ + unsigned long pages_removed; /* ring buffer pages to update, > 0 to add, < 0 to remove */ long nr_pages_to_update; struct list_head new_pages; /* new pages to add */ @@ -559,6 +561,7 @@ struct ring_buffer_iter { struct buffer_page *head_page; struct buffer_page *cache_reader_page; unsigned long cache_read; + unsigned long cache_pages_removed; u64 read_stamp; u64 page_stamp; struct ring_buffer_event *event; @@ -689,10 +692,7 @@ static void rb_time_set(rb_time_t *t, u64 val) static inline bool rb_time_read_cmpxchg(local_t *l, unsigned long expect, unsigned long set) { - unsigned long ret; - - ret = local_cmpxchg(l, expect, set); - return ret == expect; + return local_try_cmpxchg(l, &expect, set); } static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set) @@ -749,9 +749,7 @@ static void rb_time_set(rb_time_t *t, u64 val) static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set) { - u64 val; - val = local64_cmpxchg(&t->time, expect, set); - return val == expect; + return local64_try_cmpxchg(&t->time, &expect, set); } #endif @@ -947,6 +945,7 @@ static void rb_wake_up_waiters(struct irq_work *work) /** * ring_buffer_wake_waiters - wake up any waiters on this ring buffer * @buffer: The ring buffer to wake waiters on + * @cpu: The CPU buffer to wake waiters on * * In the case of a file that represents a ring buffer is closing, * it is prudent to wake up any waiters that are on this. @@ -1490,14 +1489,11 @@ static bool rb_head_page_replace(struct buffer_page *old, { 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; + return try_cmpxchg(ptr, &val, (unsigned long)&new->list); } /* @@ -1957,6 +1953,8 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) to_remove = rb_list_head(to_remove)->next; head_bit |= (unsigned long)to_remove & RB_PAGE_HEAD; } + /* Read iterators need to reset themselves when some pages removed */ + cpu_buffer->pages_removed += nr_removed; next_page = rb_list_head(to_remove)->next; @@ -1978,12 +1976,6 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) cpu_buffer->head_page = list_entry(next_page, struct buffer_page, list); - /* - * change read pointer to make sure any read iterators reset - * themselves - */ - cpu_buffer->read = 0; - /* pages are removed, resume tracing and then free the pages */ atomic_dec(&cpu_buffer->record_disabled); raw_spin_unlock_irq(&cpu_buffer->reader_lock); @@ -3003,7 +2995,6 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, { unsigned long new_index, old_index; struct buffer_page *bpage; - unsigned long index; unsigned long addr; u64 write_stamp; u64 delta; @@ -3060,8 +3051,9 @@ rb_try_to_discard(struct ring_buffer_per_cpu *cpu_buffer, */ old_index += write_mask; new_index += write_mask; - index = local_cmpxchg(&bpage->write, old_index, new_index); - if (index == old_index) { + + /* caution: old_index gets updated on cmpxchg failure */ + if (local_try_cmpxchg(&bpage->write, &old_index, new_index)) { /* update counters */ local_sub(event_length, &cpu_buffer->entries_bytes); return true; @@ -3376,7 +3368,6 @@ void ring_buffer_nest_end(struct trace_buffer *buffer) /** * ring_buffer_unlock_commit - commit a reserved * @buffer: The buffer to commit to - * @event: The event pointer to commit. * * This commits the data to the ring buffer, and releases any locks held. * @@ -4395,6 +4386,7 @@ static void rb_iter_reset(struct ring_buffer_iter *iter) iter->cache_reader_page = iter->head_page; iter->cache_read = cpu_buffer->read; + iter->cache_pages_removed = cpu_buffer->pages_removed; if (iter->head) { iter->read_stamp = cpu_buffer->read_stamp; @@ -4849,12 +4841,13 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) buffer = cpu_buffer->buffer; /* - * Check if someone performed a consuming read to - * the buffer. A consuming read invalidates the iterator - * and we need to reset the iterator in this case. + * Check if someone performed a consuming read to the buffer + * or removed some pages from the buffer. In these cases, + * iterator was invalidated and we need to reset it. */ if (unlikely(iter->cache_read != cpu_buffer->read || - iter->cache_reader_page != cpu_buffer->reader_page)) + iter->cache_reader_page != cpu_buffer->reader_page || + iter->cache_pages_removed != cpu_buffer->pages_removed)) rb_iter_reset(iter); again: @@ -5298,6 +5291,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->last_overrun = 0; rb_head_page_activate(cpu_buffer); + cpu_buffer->pages_removed = 0; } /* Must have disabled the cpu buffer then done a synchronize_rcu */ @@ -5356,7 +5350,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); /** * ring_buffer_reset_online_cpus - reset a ring buffer per CPU buffer * @buffer: The ring buffer to reset a per cpu buffer of - * @cpu: The CPU buffer to be reset */ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) { |