diff options
| author | H.J. Lu <hjl.tools@gmail.com> | 2023-04-27 13:06:15 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2023-04-28 13:38:38 -0700 |
| commit | a443bd3fb233186038b8b483959ecb7978d1abea (patch) | |
| tree | 53948f90d590b84afe22a42ec49cc2ec2fe0c700 | |
| parent | a225cb3ee9a22021312ae25c37595cd9d1995a1f (diff) | |
| download | glibc-a443bd3fb233186038b8b483959ecb7978d1abea.zip glibc-a443bd3fb233186038b8b483959ecb7978d1abea.tar.gz glibc-a443bd3fb233186038b8b483959ecb7978d1abea.tar.bz2 | |
__check_pf: Add a cancellation cleanup handler [BZ #20975]
There are reports for hang in __check_pf:
https://github.com/JoeDog/siege/issues/4
It is reproducible only under specific configurations:
1. Large number of cores (>= 64) and large number of threads (> 3X of
the number of cores) with long lived socket connection.
2. Low power (frequency) mode.
3. Power management is enabled.
While holding lock, __check_pf calls make_request which calls __sendto
and __recvmsg. Since __sendto and __recvmsg are cancellation points,
lock held by __check_pf won't be released and can cause deadlock when
thread cancellation happens in __sendto or __recvmsg. Add a cancellation
cleanup handler for __check_pf to unlock the lock when cancelled by
another thread. This fixes BZ #20975 and the siege hang issue.
| -rw-r--r-- | sysdeps/unix/sysv/linux/Makefile | 2 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/check_pf.c | 15 |
2 files changed, 17 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile index aec7a94..0160be8 100644 --- a/sysdeps/unix/sysv/linux/Makefile +++ b/sysdeps/unix/sysv/linux/Makefile @@ -529,6 +529,8 @@ sysdep_headers += \ sysdep_routines += \ netlink_assert_response \ # sysdep_routines + +CFLAGS-check_pf.c += -fexceptions endif # Don't compile the ctype glue code, since there is no old non-GNU C library. diff --git a/sysdeps/unix/sysv/linux/check_pf.c b/sysdeps/unix/sysv/linux/check_pf.c index b157c51..2b0b8b6 100644 --- a/sysdeps/unix/sysv/linux/check_pf.c +++ b/sysdeps/unix/sysv/linux/check_pf.c @@ -292,6 +292,14 @@ make_request (int fd, pid_t pid) return NULL; } +#ifdef __EXCEPTIONS +static void +cancel_handler (void *arg __attribute__((unused))) +{ + /* Release the lock. */ + __libc_lock_unlock (lock); +} +#endif void attribute_hidden @@ -304,6 +312,10 @@ __check_pf (bool *seen_ipv4, bool *seen_ipv6, struct cached_data *olddata = NULL; struct cached_data *data = NULL; +#ifdef __EXCEPTIONS + /* Make sure that lock is released when the thread is cancelled. */ + __libc_cleanup_push (cancel_handler, NULL); +#endif __libc_lock_lock (lock); if (cache_valid_p ()) @@ -338,6 +350,9 @@ __check_pf (bool *seen_ipv4, bool *seen_ipv6, } } +#ifdef __EXCEPTIONS + __libc_cleanup_pop (0); +#endif __libc_lock_unlock (lock); if (data != NULL) |