Tracepoint should only warn when a kernel API user does not respect the required preconditions (e.g. same tracepoint enabled twice, or called to remove a tracepoint that does not exist).

Silence warning in out-of-memory conditions, given that the error is returned to the caller.

This ensures that out-of-memory error-injection testing does not trigger warnings in tracepoint.c, which were seen by syzbot.

Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Reported-by: syzbot+9c0d616860575a73166a@syzkaller.appspotmail.com Reported-by: syzbot+4e9ae7fa46233396f64d@syzkaller.appspotmail.com CC: Steven Rostedt rostedt@goodmis.org CC: Ingo Molnar mingo@redhat.com CC: Peter Zijlstra peterz@infradead.org CC: Jiri Olsa jolsa@redhat.com CC: Arnaldo Carvalho de Melo acme@kernel.org CC: Alexander Shishkin alexander.shishkin@linux.intel.com CC: Namhyung Kim namhyung@kernel.org CC: stable@vger.kernel.org Link: https://lkml.kernel.org/r/001a114465e241a8720567419a72@google.com Link: https://lkml.kernel.org/r/001a1140e0de15fc910567464190@google.com --- kernel/tracepoint.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 671b13457387..1e37da2e0c25 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -207,7 +207,7 @@ static int tracepoint_add_func(struct tracepoint *tp, lockdep_is_held(&tracepoints_mutex)); old = func_add(&tp_funcs, func, prio); if (IS_ERR(old)) { - WARN_ON_ONCE(1); + WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM); return PTR_ERR(old); }

@@ -239,7 +239,7 @@ static int tracepoint_remove_func(struct tracepoint *tp, lockdep_is_held(&tracepoints_mutex)); old = func_remove(&tp_funcs, func); if (IS_ERR(old)) { - WARN_ON_ONCE(1); + WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM); return PTR_ERR(old); }