Messages in this thread Patch in this message | | | From | Namhyung Kim <> | Date | Sat, 2 Dec 2023 15:54:59 -0800 | Subject | Re: [PATCH v5 01/50] perf comm: Use regular mutex |
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On Thu, Nov 30, 2023 at 10:28 AM Ian Rogers <irogers@google.com> wrote: > > On Wed, Nov 29, 2023 at 4:56 PM Namhyung Kim <namhyung@kernel.org> wrote: > > > > On Mon, Nov 27, 2023 at 2:09 PM Ian Rogers <irogers@google.com> wrote: > > > > > > The rwsem is only after used for writing so switch to a mutex that has > > > better error checking. > > > > > > Fixes: 7a8f349e9d14 ("perf rwsem: Add debug mode that uses a mutex") > > > > I think we talked about fixing this separately, no? > > Sorry, I'm unclear on an action to do. Currently changing the > RWS_ERRORCHECK in tools/perf/util/rwsem.h will break the build without > this change.
Can it be like this?
#ifdef RWS_ERRORCHECK #define RWSEM_INITIALIZER { .lock = PTHREAD_MUTEX_INITIALIZER, } #else #define RWSEM_INITIALIZER { .lock = PTHREAD_RWLOCK_INITIALIZER, } #endif
> > > > Signed-off-by: Ian Rogers <irogers@google.com> > > > --- > > > tools/perf/util/comm.c | 10 +++++----- > > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/tools/perf/util/comm.c b/tools/perf/util/comm.c > > > index afb8d4fd2644..4ae7bc2aa9a6 100644 > > > --- a/tools/perf/util/comm.c > > > +++ b/tools/perf/util/comm.c > > > @@ -17,7 +17,7 @@ struct comm_str { > > > > > > /* Should perhaps be moved to struct machine */ > > > static struct rb_root comm_str_root; > > > -static struct rw_semaphore comm_str_lock = {.lock = PTHREAD_RWLOCK_INITIALIZER,}; > > > +static struct mutex comm_str_lock = {.lock = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP,}; > > > > IIUC it has a problem with musl libc. Actually I think it's better to > > hide the field and the pthread initializer under some macro like > > MUTEX_INITIALIZER or DEFINE_MUTEX() like in the kernel. > > Will there be enough use to justify this? I think ideally we'd not be > having global locks needing global initializers as we run into > problems like we see in metrics needing to mix counting and sampling.
I don't know but there might be a reason to use global locks. Then we need to support the initialization and it'd be better to make it easier to handle internal changes like this.
Thanks, Namhyung
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