On Fri, 2025-05-02 at 09:50 -0400, Steven Rostedt wrote: > On Fri, 02 May 2025 15:15:53 +0200 > Paul Cacheux via B4 Relay <[email protected]> > wrote: > > > From: Paul Cacheux <[email protected]> > > > > The shared trace_probe_log variable can be accessed and modified > > by multiple processes using tracefs at the same time, this new > > mutex will guarantee it's always in a coherent state. > > > > There is no guarantee that multiple errors happening at the same > > time will each have the correct error message, but at least this > > won't crash. > > > > Fixes: ab105a4fb894 ("tracing: Use tracing error_log with probe > > events") > > > > No space needed between Fixes and SOB.
Sorry about that, fixed in v3 > > > Signed-off-by: Paul Cacheux <[email protected]> > > --- > > kernel/trace/trace_probe.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/kernel/trace/trace_probe.c > > b/kernel/trace/trace_probe.c > > index > > 2eeecb6c95eea55502b83af6775b7b6f0cc5ab94..14a7a0b59cd20a8bc43e3e7c6 > > 53e986081f924c8 100644 > > --- a/kernel/trace/trace_probe.c > > +++ b/kernel/trace/trace_probe.c > > @@ -154,9 +154,11 @@ static const struct fetch_type > > *find_fetch_type(const char *type, unsigned long > > } > > > > static struct trace_probe_log trace_probe_log; > > +static DEFINE_MUTEX(trace_probe_log_lock); > > Probably should add a comment here saying something like: > > /* > * The trace_probe_log_lock only protects against the individual > * modification of the trace_probe_log. It does not protect against > * the log from producing garbage if two probes use it at the same > * time. That would only happen if two admins were trying to add > * probes simultaneously which they shouldn't be doing. > */ I sent a v3 with the space removed and this comment added, thank you for the review. > > -- Steve > > > > > > void trace_probe_log_init(const char *subsystem, int argc, const > > char **argv) > > { > > + guard(mutex)(&trace_probe_log_lock); > > trace_probe_log.subsystem = subsystem; > > trace_probe_log.argc = argc; > > trace_probe_log.argv = argv; > > @@ -165,11 +167,13 @@ void trace_probe_log_init(const char > > *subsystem, int argc, const char **argv) > > > > void trace_probe_log_clear(void) > > { > > + guard(mutex)(&trace_probe_log_lock); > > memset(&trace_probe_log, 0, sizeof(trace_probe_log)); > > } > > > > void trace_probe_log_set_index(int index) > > { > > + guard(mutex)(&trace_probe_log_lock); > > trace_probe_log.index = index; > > } > > > > @@ -178,6 +182,8 @@ void __trace_probe_log_err(int offset, int > > err_type) > > char *command, *p; > > int i, len = 0, pos = 0; > > > > + guard(mutex)(&trace_probe_log_lock); > > + > > if (!trace_probe_log.argv) > > return; > > > > Best regards, Paul Cacheux
