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author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-11 18:18:58 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-11 18:18:58 -0800 |
commit | da830e589a45f0c42eef6f3cbd07275f8893f181 (patch) | |
tree | b241c86b8a0f9acdef4b90f69ddd200548e91f2c /kernel/trace/ring_buffer.c | |
parent | 090f8ccba37034cec5a5972a70abeaae7eb0222b (diff) | |
parent | 08cd2a6960ae2e1aa7f44b44ebafa84f503a2dd1 (diff) | |
download | linux-da830e589a45f0c42eef6f3cbd07275f8893f181.tar.bz2 |
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
"These are late-v3.7 pending fixes for tracing."
Fix up trivial conflict in kernel/trace/ring_buffer.c: the NULL pointer
fix clashed with the change of type of the 'ret' variable.
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
ring-buffer: Fix race between integrity check and readers
ring-buffer: Fix NULL pointer if rb_set_head_page() fails
ftrace: Clear bits properly in reset_iter_read()
Diffstat (limited to 'kernel/trace/ring_buffer.c')
-rw-r--r-- | kernel/trace/ring_buffer.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 3c7834c24e54..ce8514feedcd 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1397,6 +1397,8 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffer) struct list_head *head_page_with_bit; head_page = &rb_set_head_page(cpu_buffer)->list; + if (!head_page) + break; prev_page = head_page->prev; first_page = pages->next; @@ -2937,7 +2939,7 @@ u64 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; - u64 ret; + u64 ret = 0; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; @@ -2952,7 +2954,8 @@ u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu) bpage = cpu_buffer->reader_page; else bpage = rb_set_head_page(cpu_buffer); - ret = bpage->page->time_stamp; + if (bpage) + ret = bpage->page->time_stamp; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); return ret; @@ -3288,6 +3291,8 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) * Splice the empty reader page into the list around the head. */ reader = rb_set_head_page(cpu_buffer); + if (!reader) + goto out; cpu_buffer->reader_page->list.next = rb_list_head(reader->list.next); cpu_buffer->reader_page->list.prev = reader->list.prev; @@ -3806,12 +3811,17 @@ void ring_buffer_read_finish(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer = iter->cpu_buffer; + unsigned long flags; /* * Ring buffer is disabled from recording, here's a good place - * to check the integrity of the ring buffer. + * to check the integrity of the ring buffer. + * Must prevent readers from trying to read, as the check + * clears the HEAD page and readers require it. */ + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_check_pages(cpu_buffer); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->buffer->resize_disabled); |