>From fde6891e59c315e4a0ec7e69182e1d6314e3795e Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Fri, 10 Feb 2023 11:17:02 -0500 Subject: [PATCH 2/5] mq_notify: use semaphore instead of barrier to sync args consumption semaphores are a much lighter primitive, and more idiomatic with current usage in the code base. --- src/mq/mq_notify.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/src/mq/mq_notify.c b/src/mq/mq_notify.c index 221591c7..a42888d2 100644 --- a/src/mq/mq_notify.c +++ b/src/mq/mq_notify.c @@ -4,10 +4,11 @@ #include #include #include +#include #include "syscall.h" struct args { - pthread_barrier_t barrier; + sem_t sem; int sock; const struct sigevent *sev; }; @@ -21,7 +22,7 @@ static void *start(void *p) void (*func)(union sigval) = args->sev->sigev_notify_function; union sigval val = args->sev->sigev_value; - pthread_barrier_wait(&args->barrier); + sem_post(&args->sem); n = recv(s, buf, sizeof(buf), MSG_NOSIGNAL|MSG_WAITALL); close(s); if (n==sizeof buf && buf[sizeof buf - 1] == 1) @@ -37,6 +38,7 @@ int mq_notify(mqd_t mqd, const struct sigevent *sev) int s; struct sigevent sev2; static const char zeros[32]; + int cs; if (!sev || sev->sigev_notify != SIGEV_THREAD) return syscall(SYS_mq_notify, mqd, sev); @@ -48,7 +50,7 @@ int mq_notify(mqd_t mqd, const struct sigevent *sev) if (sev->sigev_notify_attributes) attr = *sev->sigev_notify_attributes; else pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); - pthread_barrier_init(&args.barrier, 0, 2); + sem_init(&args.sem, 0, 0); if (pthread_create(&td, &attr, start, &args)) { __syscall(SYS_close, s); @@ -56,8 +58,10 @@ int mq_notify(mqd_t mqd, const struct sigevent *sev) return -1; } - pthread_barrier_wait(&args.barrier); - pthread_barrier_destroy(&args.barrier); + pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs); + sem_wait(&args.sem); + pthread_setcancelstate(cs, 0); + sem_destroy(&args.sem); sev2.sigev_notify = SIGEV_THREAD; sev2.sigev_signo = s; -- 2.21.0