From 342a4a2f99431ee3c72ef5cfff6449ccf2abd346 Mon Sep 17 00:00:00 2001 From: Rafael Mendonca Date: Fri, 18 Nov 2022 10:15:34 +0900 Subject: tracing/eprobe: Fix warning in filter creation The filter pointer (filterp) passed to create_filter() function must be a pointer that references a NULL pointer, otherwise, we get a warning when adding a filter option to the event probe: root@localhost:/sys/kernel/tracing# echo 'e:egroup/stat_runtime_4core sched/sched_stat_runtime \ runtime=$runtime:u32 if cpu < 4' >> dynamic_events [ 5034.340439] ------------[ cut here ]------------ [ 5034.341258] WARNING: CPU: 0 PID: 223 at kernel/trace/trace_events_filter.c:1939 create_filter+0x1db/0x250 [...] stripped [ 5034.345518] RIP: 0010:create_filter+0x1db/0x250 [...] stripped [ 5034.351604] Call Trace: [ 5034.351803] [ 5034.351959] ? process_preds+0x1b40/0x1b40 [ 5034.352241] ? rcu_read_lock_bh_held+0xd0/0xd0 [ 5034.352604] ? kasan_set_track+0x29/0x40 [ 5034.352904] ? kasan_save_alloc_info+0x1f/0x30 [ 5034.353264] create_event_filter+0x38/0x50 [ 5034.353573] __trace_eprobe_create+0x16f4/0x1d20 [ 5034.353964] ? eprobe_dyn_event_release+0x360/0x360 [ 5034.354363] ? mark_held_locks+0xa6/0xf0 [ 5034.354684] ? _raw_spin_unlock_irqrestore+0x35/0x60 [ 5034.355105] ? trace_hardirqs_on+0x41/0x120 [ 5034.355417] ? _raw_spin_unlock_irqrestore+0x35/0x60 [ 5034.355751] ? __create_object+0x5b7/0xcf0 [ 5034.356027] ? lock_is_held_type+0xaf/0x120 [ 5034.356362] ? rcu_read_lock_bh_held+0xb0/0xd0 [ 5034.356716] ? rcu_read_lock_bh_held+0xd0/0xd0 [ 5034.357084] ? kasan_set_track+0x29/0x40 [ 5034.357411] ? kasan_save_alloc_info+0x1f/0x30 [ 5034.357715] ? __kasan_kmalloc+0xb8/0xc0 [ 5034.357985] ? write_comp_data+0x2f/0x90 [ 5034.358302] ? __sanitizer_cov_trace_pc+0x25/0x60 [ 5034.358691] ? argv_split+0x381/0x460 [ 5034.358949] ? write_comp_data+0x2f/0x90 [ 5034.359240] ? eprobe_dyn_event_release+0x360/0x360 [ 5034.359620] trace_probe_create+0xf6/0x110 [ 5034.359940] ? trace_probe_match_command_args+0x240/0x240 [ 5034.360376] eprobe_dyn_event_create+0x21/0x30 [ 5034.360709] create_dyn_event+0xf3/0x1a0 [ 5034.360983] trace_parse_run_command+0x1a9/0x2e0 [ 5034.361297] ? dyn_event_release+0x500/0x500 [ 5034.361591] dyn_event_write+0x39/0x50 [ 5034.361851] vfs_write+0x311/0xe50 [ 5034.362091] ? dyn_event_seq_next+0x40/0x40 [ 5034.362376] ? kernel_write+0x5b0/0x5b0 [ 5034.362637] ? write_comp_data+0x2f/0x90 [ 5034.362937] ? __sanitizer_cov_trace_pc+0x25/0x60 [ 5034.363258] ? ftrace_syscall_enter+0x544/0x840 [ 5034.363563] ? write_comp_data+0x2f/0x90 [ 5034.363837] ? __sanitizer_cov_trace_pc+0x25/0x60 [ 5034.364156] ? write_comp_data+0x2f/0x90 [ 5034.364468] ? write_comp_data+0x2f/0x90 [ 5034.364770] ksys_write+0x158/0x2a0 [ 5034.365022] ? __ia32_sys_read+0xc0/0xc0 [ 5034.365344] __x64_sys_write+0x7c/0xc0 [ 5034.365669] ? syscall_enter_from_user_mode+0x53/0x70 [ 5034.366084] do_syscall_64+0x60/0x90 [ 5034.366356] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 5034.366767] RIP: 0033:0x7ff0b43938f3 [...] stripped [ 5034.371892] [ 5034.374720] ---[ end trace 0000000000000000 ]--- Link: https://lore.kernel.org/all/20221108202148.1020111-1-rafaelmendsr@gmail.com/ Fixes: 752be5c5c910 ("tracing/eprobe: Add eprobe filter support") Signed-off-by: Rafael Mendonca Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_eprobe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index fe4833a7b7b3..e888446d80fa 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -901,7 +901,7 @@ static int trace_eprobe_tp_update_arg(struct trace_eprobe *ep, const char *argv[ static int trace_eprobe_parse_filter(struct trace_eprobe *ep, int argc, const char *argv[]) { - struct event_filter *dummy; + struct event_filter *dummy = NULL; int i, ret, len = 0; char *p; -- cgit v1.2.1