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Merge tag 'trace-fixes-v3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

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Pull tracing fix from Steven Rostedt:
 "Rabin Vincent found a way that tracing could cause an infinite loop in
  the kernel.  The splice logic wants a full page from the ring buffer
  but the ring_buffer_wait() returns when there's any data in the ring
  buffer.  The splice code would then continue the loop waiting for a
  full page.  But if a full page never happens, the splice code will
  never sleep and just continue to loop.

  There's another case that Rabin fixed that could loop if there's no
  memory and kmalloc() constantly returns NULL"

* tag 'trace-fixes-v3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Do not risk busy looping in buffer splice
  tracing: Do not busy wait in buffer splice
This commit is contained in:
Linus Torvalds
2014-11-12 14:02:29 -08:00
parent 9d1f9c73df 07906da788
commit 15e5cda9e6
3 changed files with 70 additions and 46 deletions
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2
include/linux/ring_buffer.h
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@@ -97,7 +97,7 @@ __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *k
__ring_buffer_alloc((size), (flags), &__key); \
})
int ring_buffer_wait(struct ring_buffer *buffer, int cpu);
int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full);
int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
struct file *filp, poll_table *poll_table);