Re: [libvirt PATCH 6/7] virMutex*: Warn on error
On Thu, 2021-08-05 at 14:24 +0100, Daniel P. Berrangé wrote:
On Thu, Aug 05, 2021 at 03:08:50PM +0200, Tim Wiederhake wrote:
> `pthread_mutex_destroy`, `pthread_mutex_lock` and
> `pthread_mutex_unlock`
> return an error code that is currently ignored.
>
> Add debug information if one of these operations failed, e.g. when
> there
> is an attempt to destroy a still locked mutex or unlock and already
> unlocked mutex.
We ignore the errors because in practice we found impls don't return
any error code when using PTHREAD_MUTEX_NORMAL - it would require use
of PTHREAD_MUTEX_ERRORCHECK.
Did you actually see errors returned for real ?
Yes. Please note that I apprently copy-pasted the wrong link in the
cover letter. The pipeline for this series is correct
(https://gitlab.com/twiederh/libvirt/-/pipelines/348505233), the
pipeline for only patches 5, 6, 7 that demonstrate the non-zero return
values of pthread_mutex_{lock,unlock,destroy} is here:
https://gitlab.com/twiederh/libvirt/-/pipelines/348505770
Regards,
Tim
> Signed-off-by: Tim Wiederhake <twiederh(a)redhat.com>
> ---
> src/util/virthread.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/src/util/virthread.c b/src/util/virthread.c
> index e89c1a09fb..f64dbee9e9 100644
> --- a/src/util/virthread.c
> +++ b/src/util/virthread.c
> @@ -35,7 +35,10 @@
>
> #include "viralloc.h"
> #include "virthreadjob.h"
> +#include "virlog.h"
>
> +#define VIR_FROM_THIS VIR_FROM_THREAD
> +VIR_LOG_INIT("util.thread");
>
> int virOnce(virOnceControl *once, virOnceFunc init)
> {
> @@ -83,17 +86,23 @@ int virMutexInitRecursive(virMutex *m)
>
> void virMutexDestroy(virMutex *m)
> {
> - pthread_mutex_destroy(&m->lock);
> + if (pthread_mutex_destroy(&m->lock)) {
> + VIR_WARN("Failed to destroy mutex=%p", m);
> + }
> }
>
> void virMutexLock(virMutex *m)
> {
> - pthread_mutex_lock(&m->lock);
> + if (pthread_mutex_lock(&m->lock)) {
> + VIR_WARN("Failed to lock mutex=%p", m);
> + }
> }
>
> void virMutexUnlock(virMutex *m)
> {
> - pthread_mutex_unlock(&m->lock);
> + if (pthread_mutex_unlock(&m->lock)) {
> + VIR_WARN("Failed to unlock mutex=%p", m);
> + }
> }
>
>
> --
> 2.31.1
>
Regards,
Daniel