[ltt-dev] [UST PATCH 2/3] ust-consumerd: fix exit race log corruption

[nils.carlson@ericsson.com (Nils Carlson)]

merged.

On Wed, 27 Apr 2011, Jason Wessel wrote:

> In the following scenario on an SMP system the ust-consumerd can end
> up not properly closing out file handles which leads to log
> corruption:
>  * usttrace -m -l small_quick_app_lots_of_malloc_and_free
>  * The app completes and usttrace sees and sends the SIGTERM to ust-consumerd
>  * The ust-consumerd main thread will exit and the _exit() handlers
>    kills off the remaining pthreads without everything getting closed out
>
> The solution to the problem is to introduce an active_thread count for
> the private ustconsumer_instance.  This counter will be zeroed out
> when it is safe to completely shutdown the main thread, which will
> subsequently run the _exit() handlers.
>
> Signed-off-by: Jason Wessel <jason.wessel at windriver.com>
> ---
> include/ust/ustconsumer.h       |    1 +
> libustconsumer/libustconsumer.c |   10 +++++++++-
> 2 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/include/ust/ustconsumer.h b/include/ust/ustconsumer.h
> index f99f8f1..cde8440 100644
> --- a/include/ust/ustconsumer.h
> +++ b/include/ust/ustconsumer.h
> @@ -89,6 +89,7 @@ struct ustconsumer_instance {
> 	char *sock_path;
> 	pthread_mutex_t mutex;
> 	int active_buffers;
> +	int active_threads;
> };
>
> /**
> diff --git a/libustconsumer/libustconsumer.c b/libustconsumer/libustconsumer.c
> index 6f6d4bb..a723540 100644
> --- a/libustconsumer/libustconsumer.c
> +++ b/libustconsumer/libustconsumer.c
> @@ -543,6 +543,10 @@ void *consumer_thread(void *arg)
> 	int result;
> 	sigset_t sigset;
>
> +	pthread_mutex_lock(&args->instance->mutex);
> +	args->instance->active_threads++;
> +	pthread_mutex_unlock(&args->instance->mutex);
> +
> 	if(args->instance->callbacks->on_new_thread)
> 		args->instance->callbacks->on_new_thread(args->instance->callbacks);
>
> @@ -584,6 +588,10 @@ void *consumer_thread(void *arg)
> 	if(args->instance->callbacks->on_close_thread)
> 		args->instance->callbacks->on_close_thread(args->instance->callbacks);
>
> +	pthread_mutex_lock(&args->instance->mutex);
> +	args->instance->active_threads--;
> +	pthread_mutex_unlock(&args->instance->mutex);
> +
> 	free((void *)args->channel);
> 	free(args);
> 	return NULL;
> @@ -735,7 +743,7 @@ int ustconsumer_start_instance(struct ustconsumer_instance *instance)
>
> 		if (instance->quit_program) {
> 			pthread_mutex_lock(&instance->mutex);
> -			if(instance->active_buffers == 0) {
> +			if(instance->active_buffers == 0 && instance->active_threads == 0) {
> 				pthread_mutex_unlock(&instance->mutex);
> 				break;
> 			}
> -- 
> 1.7.1
>
>
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