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| author | Sven Schnelle <svens@linux.ibm.com> | 2022-02-14 16:44:56 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-03-16 16:23:41 +0300 |
| commit | 4d2889691570e76289486a123ad34323992c1057 (patch) | |
| tree | f39d7cc6b286f8ead2947da2d57afdbc2c07252c /kernel/trace | |
| parent | 041616a22c40b7093c90010e2f52581776d4392a (diff) | |
| download | linux-4d2889691570e76289486a123ad34323992c1057.tar.xz | |
tracing: Ensure trace buffer is at least 4096 bytes large
[ Upstream commit 7acf3a127bb7c65ff39099afd78960e77b2ca5de ]
Booting the kernel with 'trace_buf_size=1' give a warning at
boot during the ftrace selftests:
[ 0.892809] Running postponed tracer tests:
[ 0.892893] Testing tracer function:
[ 0.901899] Callback from call_rcu_tasks_trace() invoked.
[ 0.983829] Callback from call_rcu_tasks_rude() invoked.
[ 1.072003] .. bad ring buffer .. corrupted trace buffer ..
[ 1.091944] Callback from call_rcu_tasks() invoked.
[ 1.097695] PASSED
[ 1.097701] Testing dynamic ftrace: .. filter failed count=0 ..FAILED!
[ 1.353474] ------------[ cut here ]------------
[ 1.353478] WARNING: CPU: 0 PID: 1 at kernel/trace/trace.c:1951 run_tracer_selftest+0x13c/0x1b0
Therefore enforce a minimum of 4096 bytes to make the selftest pass.
Link: https://lkml.kernel.org/r/20220214134456.1751749-1-svens@linux.ibm.com
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 86fb77c2ace5..01002656f1ae 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1496,10 +1496,12 @@ static int __init set_buf_size(char *str) if (!str) return 0; buf_size = memparse(str, &str); - /* nr_entries can not be zero */ - if (buf_size == 0) - return 0; - trace_buf_size = buf_size; + /* + * nr_entries can not be zero and the startup + * tests require some buffer space. Therefore + * ensure we have at least 4096 bytes of buffer. + */ + trace_buf_size = max(4096UL, buf_size); return 1; } __setup("trace_buf_size=", set_buf_size); |