diff options
| -rw-r--r-- | kernel/trace/ring_buffer.c | 56 |
1 files changed, 52 insertions, 4 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8fa2a84f714f..1c61a8cd7b99 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -742,6 +742,48 @@ static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set) } #endif +/* + * Enable this to make sure that the event passed to + * ring_buffer_event_time_stamp() is not committed and also + * is on the buffer that it passed in. + */ +//#define RB_VERIFY_EVENT +#ifdef RB_VERIFY_EVENT +static struct list_head *rb_list_head(struct list_head *list); +static void verify_event(struct ring_buffer_per_cpu *cpu_buffer, + void *event) +{ + struct buffer_page *page = cpu_buffer->commit_page; + struct buffer_page *tail_page = READ_ONCE(cpu_buffer->tail_page); + struct list_head *next; + long commit, write; + unsigned long addr = (unsigned long)event; + bool done = false; + int stop = 0; + + /* Make sure the event exists and is not committed yet */ + do { + if (page == tail_page || WARN_ON_ONCE(stop++ > 100)) + done = true; + commit = local_read(&page->page->commit); + write = local_read(&page->write); + if (addr >= (unsigned long)&page->page->data[commit] && + addr < (unsigned long)&page->page->data[write]) + return; + + next = rb_list_head(page->list.next); + page = list_entry(next, struct buffer_page, list); + } while (!done); + WARN_ON_ONCE(1); +} +#else +static inline void verify_event(struct ring_buffer_per_cpu *cpu_buffer, + void *event) +{ +} +#endif + + static inline u64 rb_time_stamp(struct trace_buffer *buffer); /** @@ -772,13 +814,19 @@ u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer, if (event->type_len == RINGBUF_TYPE_TIME_STAMP) return rb_event_time_stamp(event); + nest = local_read(&cpu_buffer->committing); + verify_event(cpu_buffer, event); + if (WARN_ON_ONCE(!nest)) + goto fail; + /* Read the current saved nesting level time stamp */ - nest = local_read(&cpu_buffer->committing) - 1; - if (likely(nest < MAX_NEST)) + if (likely(--nest < MAX_NEST)) return cpu_buffer->event_stamp[nest]; - WARN_ON_ONCE(1); + /* Shouldn't happen, warn if it does */ + WARN_ONCE(1, "nest (%d) greater than max", nest); + fail: /* Can only fail on 32 bit */ if (!rb_time_read(&cpu_buffer->write_stamp, &ts)) /* Screw it, just read the current time */ @@ -2750,7 +2798,7 @@ rb_update_event(struct ring_buffer_per_cpu *cpu_buffer, u64 delta = info->delta; unsigned int nest = local_read(&cpu_buffer->committing) - 1; - if (nest < MAX_NEST) + if (!WARN_ON_ONCE(nest >= MAX_NEST)) cpu_buffer->event_stamp[nest] = info->ts; /* |