Messages in this thread Patch in this message | | | Date | Tue, 11 Dec 2012 10:19:43 +0100 | From | Ingo Molnar <> | Subject | [GIT PULL] perf fixes for v3.8 |
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Linus,
Please pull the latest perf-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-for-linus
HEAD: 08cd2a6960ae2e1aa7f44b44ebafa84f503a2dd1 Merge branch 'tip/perf/urgent-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/urgent
These are late-v3.7 pending fixes for tracing.
Thanks,
Ingo
------------------> Dan Carpenter (1): ftrace: Clear bits properly in reset_iter_read()
Steven Rostedt (2): ring-buffer: Fix NULL pointer if rb_set_head_page() fails ring-buffer: Fix race between integrity check and readers
kernel/trace/ftrace.c | 2 +- kernel/trace/ring_buffer.c | 16 +++++++++++++--- 2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9dcf15d..51b7159 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2437,7 +2437,7 @@ static void reset_iter_read(struct ftrace_iterator *iter) { iter->pos = 0; iter->func_pos = 0; - iter->flags &= ~(FTRACE_ITER_PRINTALL & FTRACE_ITER_HASH); + iter->flags &= ~(FTRACE_ITER_PRINTALL | FTRACE_ITER_HASH); } static void *t_start(struct seq_file *m, loff_t *pos) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b979426..4cb5e51 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1396,6 +1396,8 @@ 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; @@ -2934,7 +2936,7 @@ 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; + unsigned long ret = 0; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; @@ -2949,7 +2951,8 @@ unsigned long 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; @@ -3260,6 +3263,8 @@ 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; @@ -3778,12 +3783,17 @@ 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);
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