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| author | Ingo Molnar <mingo@kernel.org> | 2016-09-15 08:24:53 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-09-15 08:24:53 +0200 |
| commit | d4b80afbba49e968623330f1336da8c724da8aad (patch) | |
| tree | a9478bd77d8b001a6a7119328d34e9666d7bfe93 /kernel/events/ring_buffer.c | |
| parent | fcd709ef20a9d83bdb7524d27cd6719dac8690a0 (diff) | |
| parent | 4cea8776571b18db7485930cb422faa739580c8c (diff) | |
| download | talos-op-linux-d4b80afbba49e968623330f1336da8c724da8aad.tar.gz talos-op-linux-d4b80afbba49e968623330f1336da8c724da8aad.zip | |
Merge branch 'linus' into x86/asm, to pick up recent fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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 |
