Hi Shehab,
Please provide a link to a lttng-ust git tree or an actual patch (git format-patch).
This will help any person who might be interested in helping you including
myself.
Cheers
On Tue, May 01, 2018 at 09:31:52AM -0400, Shehab Elsayed wrote:
> Hi,
>
> I am trying to create wrappers for pthreads conditional variables functions
> (wait, signal and broadcast) to insert tracepoints. I followed the same
> approach done for the mutex functions already provided with lttng, however
> I am running into some problems. Mainly the applications seem to get stuck
> when the conditional variable wrappers are enabled.
>
> Here is my implementation for the wrapper functions:
> int pthread_cond_wait(pthread_cond_t *condition, pthread_mutex_t
> *mutex)
>
> {
>
> static int (*cond_wait)(pthread_cond_t *, pthread_mutex_t
> *);
> int retval;
>
>
>
> if (!cond_wait)
> {
>
> cond_wait = dlsym(RTLD_NEXT, "pthread_cond_wait");
>
> if (!cond_wait)
> {
>
> if (thread_in_trace)
> {
>
>
> abort();
>
>
> }
>
> fprintf(stderr, "unable to initialize pthread wrapper
> library.\n");
> return EINVAL;
>
>
> }
>
>
> }
>
> if (thread_in_trace)
> {
>
> return cond_wait(condition, mutex);
>
>
> }
>
>
>
> thread_in_trace =
> 1;
>
> tracepoint(lttng_ust_pthread, pthread_cond_wait_begin, condition,
> mutex,
>
> LTTNG_UST_CALLER_IP());
>
> retval = cond_wait(condition, mutex);
>
> tracepoint(lttng_ust_pthread, pthread_cond_wait_end, condition,
> mutex,
>
> LTTNG_UST_CALLER_IP());
>
> thread_in_trace =
> 0;
>
> return retval;
>
> }
>
>
>
> int pthread_cond_signal(pthread_cond_t
> *condition)
>
> {
>
> static int (*cond_signal)(pthread_cond_t
> *);
>
> int retval;
>
>
>
> if (!cond_signal)
> {
>
> cond_signal = dlsym(RTLD_NEXT, "pthread_cond_signal");
>
> if (!cond_signal)
> {
>
> if (thread_in_trace)
> {
>
>
> abort();
>
>
> }
>
> fprintf(stderr, "unable to initialize pthread wrapper
> library.\n");
> return EINVAL;
>
>
> }
>
>
> }
>
> if (thread_in_trace)
> {
>
> return cond_signal(condition);
>
>
> }
>
>
>
> thread_in_trace =
> 1;
>
> tracepoint(lttng_ust_pthread, pthread_cond_signal_begin,
> condition,
> LTTNG_UST_CALLER_IP());
>
> retval = cond_signal(condition);
>
> tracepoint(lttng_ust_pthread, pthread_cond_signal_end,
> condition,
> LTTNG_UST_CALLER_IP());
>
> thread_in_trace =
> 0;
>
> return retval;
>
> }
>
>
>
> int pthread_cond_broadcast(pthread_cond_t
> *condition)
>
> {
>
> static int (*cond_broadcast)(pthread_cond_t
> *);
> int retval;
>
>
>
> if (!cond_broadcast)
> {
>
> cond_broadcast = dlsym(RTLD_NEXT, "pthread_cond_broadcast");
>
> if (!cond_broadcast)
> {
>
> if (thread_in_trace)
> {
>
>
> abort();
>
>
> }
>
> fprintf(stderr, "unable to initialize pthread wrapper
> library.\n");
> return EINVAL;
>
>
> }
>
>
> }
>
> if (thread_in_trace)
> {
>
> return cond_broadcast(condition);
>
>
> }
>
>
>
> thread_in_trace =
> 1;
>
> tracepoint(lttng_ust_pthread, pthread_cond_broadcast_begin,
> condition,
> LTTNG_UST_CALLER_IP());
>
> retval = cond_broadcast(condition);
>
> tracepoint(lttng_ust_pthread, pthread_cond_broadcast_end,
> condition,
> LTTNG_UST_CALLER_IP());
>
> thread_in_trace =
> 0;
>
> return retval;
>
> }
>
> Things I have tried:
> 1- Comment out pthread_cond_wait function --> segmentation fault
> 2- Comment out pthread_cond_signal and _broadcast --> stuck (I can see the
> program is still running but nor forward progress is being made) compared
> to the case when the wrappers are not preloaded.
> 3- Comment out all tracepoint related code (basically the wrapper just call
> the corresponding pthreads function) --> same results as points 1 and 2.
>
> Any idea what might be causing this or how I could debug this problem?
>
> Thank you very much in advance.
>
> Best Regards,
> Shehab
> int pthread_cond_wait(pthread_cond_t *condition, pthread_mutex_t *mutex)
> {
> static int (*cond_wait)(pthread_cond_t *, pthread_mutex_t *);
> int retval;
>
> if (!cond_wait) {
> cond_wait = dlsym(RTLD_NEXT, "pthread_cond_wait");
> if (!cond_wait) {
> if (thread_in_trace) {
> abort();
> }
> fprintf(stderr, "unable to initialize pthread wrapper library.\n");
> return EINVAL;
> }
> }
> if (thread_in_trace) {
> return cond_wait(condition, mutex);
> }
>
> thread_in_trace = 1;
> tracepoint(lttng_ust_pthread, pthread_cond_wait_begin, condition, mutex,
> LTTNG_UST_CALLER_IP());
> retval = cond_wait(condition, mutex);
> tracepoint(lttng_ust_pthread, pthread_cond_wait_end, condition, mutex,
> LTTNG_UST_CALLER_IP());
> thread_in_trace = 0;
> return retval;
> }
>
> int pthread_cond_signal(pthread_cond_t *condition)
> {
> static int (*cond_signal)(pthread_cond_t *);
> int retval;
>
> if (!cond_signal) {
> cond_signal = dlsym(RTLD_NEXT, "pthread_cond_signal");
> if (!cond_signal) {
> if (thread_in_trace) {
> abort();
> }
> fprintf(stderr, "unable to initialize pthread wrapper library.\n");
> return EINVAL;
> }
> }
> if (thread_in_trace) {
> return cond_signal(condition);
> }
>
> thread_in_trace = 1;
> tracepoint(lttng_ust_pthread, pthread_cond_signal_begin, condition,
> LTTNG_UST_CALLER_IP());
> retval = cond_signal(condition);
> tracepoint(lttng_ust_pthread, pthread_cond_signal_end, condition,
> LTTNG_UST_CALLER_IP());
> thread_in_trace = 0;
> return retval;
> }
>
> int pthread_cond_broadcast(pthread_cond_t *condition)
> {
> static int (*cond_broadcast)(pthread_cond_t *);
> int retval;
>
> if (!cond_broadcast) {
> cond_broadcast = dlsym(RTLD_NEXT, "pthread_cond_broadcast");
> if (!cond_broadcast) {
> if (thread_in_trace) {
> abort();
> }
> fprintf(stderr, "unable to initialize pthread wrapper library.\n");
> return EINVAL;
> }
> }
> if (thread_in_trace) {
> return cond_broadcast(condition);
> }
>
> thread_in_trace = 1;
> tracepoint(lttng_ust_pthread, pthread_cond_broadcast_begin, condition,
> LTTNG_UST_CALLER_IP());
> retval = cond_broadcast(condition);
> tracepoint(lttng_ust_pthread, pthread_cond_broadcast_end, condition,
> LTTNG_UST_CALLER_IP());
> thread_in_trace = 0;
> return retval;
> }
> _______________________________________________
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> lttng-dev at lists.lttng.org
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--
Jonathan Rajotte-Julien
EfficiOS