diff options
| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2017-04-19 12:07:08 -0400 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2017-05-17 15:08:23 -0400 |
| commit | f7f44f58872253e8f5d8a9a86bf3f5aea265af29 (patch) | |
| tree | 38eb1e6222dc97cd6b3626560fe78104efd14510 /kernel | |
| parent | 73270592d94b8e740d0ac044fc48c7749df593a0 (diff) | |
tracing: Allocate the snapshot buffer before enabling probe
[ Upstream commit df62db5be2e5f070ecd1a5ece5945b590ee112e0 ]
Currently the snapshot trigger enables the probe and then allocates the
snapshot. If the probe triggers before the allocation, it could cause the
snapshot to fail and turn tracing off. It's best to allocate the snapshot
buffer first, and then enable the trigger. If something goes wrong in the
enabling of the trigger, the snapshot buffer is still allocated, but it can
also be freed by the user by writting zero into the snapshot buffer file.
Also add a check of the return status of alloc_snapshot().
Cc: stable@vger.kernel.org
Fixes: 77fd5c15e3 ("tracing: Add snapshot trigger to function probes")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 61ea7e8cdde5..a4c0ae70c6dd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6025,11 +6025,13 @@ ftrace_trace_snapshot_callback(struct ftrace_hash *hash, return ret; out_reg: - ret = register_ftrace_function_probe(glob, ops, count); + ret = alloc_snapshot(&global_trace); + if (ret < 0) + goto out; - if (ret >= 0) - alloc_snapshot(&global_trace); + ret = register_ftrace_function_probe(glob, ops, count); + out: return ret < 0 ? ret : 0; } |