Mailing List Archive

commit a53079e385abcfba4bfe88414a52e94c1dc444c5
Author: Poul-Henning Kamp <phk@FreeBSD.org>
Date: Tue Mar 29 18:04:45 2022 +0000

Change the OS/X workaround for pthread_cond_timedwait() returning EINVAL

diff --git a/bin/varnishd/cache/cache_lck.c b/bin/varnishd/cache/cache_lck.c
index 827a12343..6615897eb 100644
--- a/bin/varnishd/cache/cache_lck.c
+++ b/bin/varnishd/cache/cache_lck.c
@@ -229,34 +229,6 @@ Lck_CondWaitUntil(pthread_cond_t *cond, struct lock *lck, vtim_real when)
struct ilck *ilck;
struct timespec ts;

-#if defined (__APPLE__)
- /*
- * I hate woo-doo programming in all it's forms and all it's
- * manifestations, but for reasons I utterly fail to isolate
- * yielding here is stops OSX from throwing a EINVAL to the
- * pthread_cond_wait(3) call.
- *
- * I have tried very hard to determine if any of the three
- * arguments are in fact invalid, and found nothing which
- * even hints that it might be the case, and with high probability
- * repeating the failed call with the exact same arguments
- * will succeed.
- *
- * If you want to dive into this you can trigger the situation
- * approx 30% of the time with:
- *
- * cd .../vmods && make -j check
- *
- * Env:
- * Darwin Kernel Version 20.5.0:
- * Sat May 8 05:10:31 PDT 2021;
- * root:xnu-7195.121.3~9/RELEASE_ARM64_T8101 arm64
- *
- * 20211027 /phk
- */
- pthread_yield_np();
-#endif
-
AN(lck);
CAST_OBJ_NOTNULL(ilck, lck->priv, ILCK_MAGIC);
AN(ilck->held);
@@ -270,6 +242,34 @@ Lck_CondWaitUntil(pthread_cond_t *cond, struct lock *lck, vtim_real when)
ts = VTIM_timespec(when);
assert(ts.tv_nsec >= 0 && ts.tv_nsec <= 999999999);
errno = pthread_cond_timedwait(cond, &ilck->mtx, &ts);
+#if defined (__APPLE__)
+ /*
+ * I hate woo-doo programming in all it's forms and all it's
+ * manifestations, but for reasons I utterly fail to isolate,
+ * OSX sometimes throws an EINVAL.
+ *
+ * I have tried very hard to determine if any of the three
+ * arguments are in fact invalid, and found nothing which
+ * even hints that it might be the case.
+ *
+ * So far I have yet to see a failure if the exact same
+ * call is repeated after a very short sleep.
+ *
+ * Calling pthread_yield_np() instead of sleaping /mostly/
+ * works as well, but still fails sometimes.
+ *
+ * Env:
+ * Darwin Kernel Version 20.5.0:
+ * Sat May 8 05:10:31 PDT 2021;
+ * root:xnu-7195.121.3~9/RELEASE_ARM64_T8101 arm64
+ *
+ * 20220329 /phk
+ */
+ if (errno == EINVAL) {
+ usleep(100);
+ errno = pthread_cond_timedwait(cond, &ilck->mtx, &ts);
+ }
+#endif
assert(errno == 0 ||
errno == ETIMEDOUT ||
errno == EINTR);
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