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| author | Russell King <rmk+kernel@armlinux.org.uk> | 2016-10-06 10:56:43 +0300 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2016-10-06 10:56:43 +0300 |
| commit | 301a36fa700f9add6e14f5a95c7573e01578343a (patch) | |
| tree | 6ff94ff3b08b838353b9127eb5f8055b3de6b25f /kernel/events/ring_buffer.c | |
| parent | b828f960215f02e5d2c88bbd27565c694254a15a (diff) | |
| parent | b60752f2b20c167859943e001727f0d4da419b23 (diff) | |
| download | linux-301a36fa700f9add6e14f5a95c7573e01578343a.tar.xz | |
Merge branches 'misc' and 'sa1111-base' into for-linus
Diffstat (limited to 'kernel/events/ring_buffer.c')
| -rw-r--r-- | kernel/events/ring_buffer.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index ae9b90dc9a5a..257fa460b846 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -330,15 +330,22 @@ void *perf_aux_output_begin(struct perf_output_handle *handle, if (!rb) return NULL; - if (!rb_has_aux(rb) || !atomic_inc_not_zero(&rb->aux_refcount)) + if (!rb_has_aux(rb)) goto err; /* - * If rb::aux_mmap_count is zero (and rb_has_aux() above went through), - * the aux buffer is in perf_mmap_close(), about to get freed. + * If aux_mmap_count is zero, the aux buffer is in perf_mmap_close(), + * about to get freed, so we leave immediately. + * + * Checking rb::aux_mmap_count and rb::refcount has to be done in + * the same order, see perf_mmap_close. Otherwise we end up freeing + * aux pages in this path, which is a bug, because in_atomic(). */ if (!atomic_read(&rb->aux_mmap_count)) - goto err_put; + goto err; + + if (!atomic_inc_not_zero(&rb->aux_refcount)) + goto err; /* * Nesting is not supported for AUX area, make sure nested |