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authorSven Schnelle <svens@linux.ibm.com>2022-02-14 14:44:56 +0100
committerSteven Rostedt (Google) <rostedt@goodmis.org>2022-02-25 12:07:01 -0500
commit7acf3a127bb7c65ff39099afd78960e77b2ca5de (patch)
treedbbb033b3014b15a4228b435e7697e8ac69933c7 /kernel
parentbc82c38a6933aab308387d4aca47e0a05de7b553 (diff)
tracing: Ensure trace buffer is at least 4096 bytes large
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7c2578efde26..3050892d1812 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1474,10 +1474,12 @@ 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);