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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2017-04-19 12:07:08 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-04-27 09:09:31 +0200
commit1dfb1c7bd63f7ea8975f32ddd04a9c4406f8d64d (patch)
tree9ef5509ebd64cda2b3c73397764869fd6c3c4b48 /kernel/trace
parentc9460fbceb2f3efa1d20050cdbffa51ec025745a (diff)
tracing: Allocate the snapshot buffer before enabling probe
commit df62db5be2e5f070ecd1a5ece5945b590ee112e0 upstream. 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(). Fixes: 77fd5c15e3 ("tracing: Add snapshot trigger to function probes") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 059233abcfcf..4c21c0b7dc91 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6060,11 +6060,13 @@ 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;
}