From de9f498d2b381de1abf654ca3459c4f01227b5cd Mon Sep 17 00:00:00 2001 From: Changbin Du Date: Tue, 8 Feb 2022 22:07:25 +0800 Subject: perf trace: Avoid early exit due SIGCHLD from non-workload processes The function trace__symbols_init() runs "perf-read-vdso32" and that ends up with a SIGCHLD delivered to 'perf'. And this SIGCHLD make perf exit early. 'perf trace' should exit only if the SIGCHLD is from our workload process. So let's use sigaction() instead of signal() to match such condition. Committer notes: Use memset to zero the 'struct sigaction' variable as the '= { 0 }' method isn't accepted in many compiler versions, e.g.: 4 34.02 alpine:3.6 : FAIL clang version 4.0.0 (tags/RELEASE_400/final) builtin-trace.c:4897:35: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces] struct sigaction sigchld_act = { 0 }; ^ {} builtin-trace.c:4897:37: error: missing field 'sa_mask' initializer [-Werror,-Wmissing-field-initializers] struct sigaction sigchld_act = { 0 }; ^ 2 errors generated. 6 32.60 alpine:3.8 : FAIL gcc version 6.4.0 (Alpine 6.4.0) builtin-trace.c:4897:35: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces] struct sigaction sigchld_act = { 0 }; ^ {} builtin-trace.c:4897:37: error: missing field 'sa_mask' initializer [-Werror,-Wmissing-field-initializers] struct sigaction sigchld_act = { 0 }; ^ 2 errors generated. 7 34.82 alpine:3.9 : FAIL gcc version 8.3.0 (Alpine 8.3.0) builtin-trace.c:4897:35: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces] struct sigaction sigchld_act = { 0 }; ^ {} builtin-trace.c:4897:37: error: missing field 'sa_mask' initializer [-Werror,-Wmissing-field-initializers] struct sigaction sigchld_act = { 0 }; ^ 2 errors generated. Signed-off-by: Changbin Du Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: Ingo Molnar Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20220208140725.3947-1-changbin.du@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) (limited to 'tools') diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 32844d8a0ea5..52b137a184a6 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1536,13 +1536,20 @@ static size_t trace__fprintf_tstamp(struct trace *trace, u64 tstamp, FILE *fp) return fprintf(fp, " ? "); } +static pid_t workload_pid = -1; static bool done = false; static bool interrupted = false; -static void sig_handler(int sig) +static void sighandler_interrupt(int sig __maybe_unused) { - done = true; - interrupted = sig == SIGINT; + done = interrupted = true; +} + +static void sighandler_chld(int sig __maybe_unused, siginfo_t *info, + void *context __maybe_unused) +{ + if (info->si_pid == workload_pid) + done = true; } static size_t trace__fprintf_comm_tid(struct trace *trace, struct thread *thread, FILE *fp) @@ -3938,7 +3945,6 @@ static int trace__run(struct trace *trace, int argc, const char **argv) bool draining = false; trace->live = true; - signal(SIGCHLD, sig_handler); if (!trace->raw_augmented_syscalls) { if (trace->trace_syscalls && trace__add_syscall_newtp(trace)) @@ -4018,6 +4024,7 @@ static int trace__run(struct trace *trace, int argc, const char **argv) fprintf(trace->output, "Couldn't run the workload!\n"); goto out_delete_evlist; } + workload_pid = evlist->workload.pid; } err = evlist__open(evlist); @@ -4887,10 +4894,16 @@ int cmd_trace(int argc, const char **argv) const char * const trace_subcommands[] = { "record", NULL }; int err = -1; char bf[BUFSIZ]; + struct sigaction sigchld_act; signal(SIGSEGV, sighandler_dump_stack); signal(SIGFPE, sighandler_dump_stack); - signal(SIGINT, sig_handler); + signal(SIGINT, sighandler_interrupt); + + memset(&sigchld_act, 0, sizeof(sigchld_act)); + sigchld_act.sa_flags = SA_SIGINFO; + sigchld_act.sa_sigaction = sighandler_chld; + sigaction(SIGCHLD, &sigchld_act, NULL); trace.evlist = evlist__new(); trace.sctbl = syscalltbl__new(); -- cgit v1.2.3