4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mathieu Desnoyers mathieu.desnoyers@efficios.com
commit d66a270be3310d7aa132fec0cea77d3d32a0ff75 upstream.
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.
Link: https://lkml.kernel.org/r/001a114465e241a8720567419a72@google.com Link: https://lkml.kernel.org/r/001a1140e0de15fc910567464190@google.com Link: http://lkml.kernel.org/r/20180315124424.32319-1-mathieu.desnoyers@efficios.c...
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 Fixes: de7b2973903c6 ("tracepoint: Use struct pointer instead of name hash for reg/unreg tracepoints") Reported-by: syzbot+9c0d616860575a73166a@syzkaller.appspotmail.com Reported-by: syzbot+4e9ae7fa46233396f64d@syzkaller.appspotmail.com Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/tracepoint.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -202,7 +202,7 @@ static int tracepoint_add_func(struct tr 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); }
@@ -235,7 +235,7 @@ static int tracepoint_remove_func(struct 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); }