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Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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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()
This commit is contained in:
Linus Torvalds 2012-12-11 18:18:58 -08:00
commit da830e589a
2 changed files with 14 additions and 4 deletions
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2
kernel/trace/ftrace.c
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@ -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)

16
kernel/trace/ring_buffer.c
View File

@ -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);