[lttng-dev] [PATCH lttng-tools 1/2] Cleanup: use CMM accessors for consumer_quit variable

[Jérémie Galarneau]

The first patch has been merged in master and stable-2.10. The second
one has been merged in master, stable-2.10, stable-2.9, and
stable-2.8.

Thanks!
Jérémie

On 16 June 2017 at 17:23, Mathieu Desnoyers
<mathieu.desnoyers at efficios.com> wrote:
> Use CMM_LOAD_SHARED and CMM_STORE_SHARED, which are strictly
> equivalent to a volatile variable, in line with the rest of the
> lttng-tools project.
>
> Also move its declaration to a header, rather than having multiple
> declarations in C files, now following our coding style.
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> ---
>  src/common/consumer/consumer.c               | 10 +++++-----
>  src/common/consumer/consumer.h               |  6 ++++++
>  src/common/kernel-consumer/kernel-consumer.c |  1 -
>  src/common/ust-consumer/ust-consumer.c       |  1 -
>  4 files changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/src/common/consumer/consumer.c b/src/common/consumer/consumer.c
> index d07e5b4..9834322 100644
> --- a/src/common/consumer/consumer.c
> +++ b/src/common/consumer/consumer.c
> @@ -76,7 +76,7 @@ int data_consumption_paused;
>   * Also updated by the signal handler (consumer_should_exit()). Read by the
>   * polling threads.
>   */
> -volatile int consumer_quit;
> +int consumer_quit;
>
>  /*
>   * Global hash table containing respectively metadata and data streams. The
> @@ -1227,7 +1227,7 @@ void lttng_consumer_should_exit(struct lttng_consumer_local_data *ctx)
>  {
>         ssize_t ret;
>
> -       consumer_quit = 1;
> +       CMM_STORE_SHARED(consumer_quit, 1);
>         ret = lttng_write(ctx->consumer_should_quit[1], "4", 1);
>         if (ret < 1) {
>                 PERROR("write consumer quit");
> @@ -2526,7 +2526,7 @@ void *consumer_thread_data_poll(void *data)
>                 pthread_mutex_unlock(&consumer_data.lock);
>
>                 /* No FDs and consumer_quit, consumer_cleanup the thread */
> -               if (nb_fd == 0 && consumer_quit == 1) {
> +               if (nb_fd == 0 && CMM_LOAD_SHARED(consumer_quit) == 1) {
>                         err = 0;        /* All is OK */
>                         goto end;
>                 }
> @@ -3203,7 +3203,7 @@ void *consumer_thread_sessiond_poll(void *data)
>                         err = 0;
>                         goto end;
>                 }
> -               if (consumer_quit) {
> +               if (CMM_LOAD_SHARED(consumer_quit)) {
>                         DBG("consumer_thread_receive_fds received quit from signal");
>                         err = 0;        /* All is OK */
>                         goto end;
> @@ -3228,7 +3228,7 @@ end:
>          * when all fds have hung up, the polling thread
>          * can exit cleanly
>          */
> -       consumer_quit = 1;
> +       CMM_STORE_SHARED(consumer_quit, 1);
>
>         /*
>          * Notify the data poll thread to poll back again and test the
> diff --git a/src/common/consumer/consumer.h b/src/common/consumer/consumer.h
> index 7375373..220dbb4 100644
> --- a/src/common/consumer/consumer.h
> +++ b/src/common/consumer/consumer.h
> @@ -604,6 +604,12 @@ struct lttng_consumer_global_data {
>         struct lttng_ht *stream_per_chan_id_ht;
>  };
>
> +/*
> + * Set to nonzero when the consumer is exiting. Updated by signal
> + * handler and thread exit, read by threads.
> + */
> +extern int consumer_quit;
> +
>  /* Flag used to temporarily pause data consumption from testpoints. */
>  extern int data_consumption_paused;
>
> diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
> index b5afc73..8d00a0d 100644
> --- a/src/common/kernel-consumer/kernel-consumer.c
> +++ b/src/common/kernel-consumer/kernel-consumer.c
> @@ -48,7 +48,6 @@
>
>  extern struct lttng_consumer_global_data consumer_data;
>  extern int consumer_poll_timeout;
> -extern volatile int consumer_quit;
>
>  /*
>   * Take a snapshot for a specific fd
> diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
> index 99803a6..4297d60 100644
> --- a/src/common/ust-consumer/ust-consumer.c
> +++ b/src/common/ust-consumer/ust-consumer.c
> @@ -51,7 +51,6 @@
>
>  extern struct lttng_consumer_global_data consumer_data;
>  extern int consumer_poll_timeout;
> -extern volatile int consumer_quit;
>
>  /*
>   * Free channel object and all streams associated with it. This MUST be used
> --
> 2.1.4
>



-- 
Jérémie Galarneau
EfficiOS Inc.
http://www.efficios.com