[lttng-dev] [PATCH lttng-tools 1/3] epoll/poll compat: expose interruptible API

[Jérémie Galarneau]

Series merged in master and stable-2.11.

Thanks,
Jérémie

On Thu, May 16, 2019 at 03:08:50PM -0400, Mathieu Desnoyers wrote:
> Some use of the epoll/poll wrapper require interruption
> by signals to make the poll call return -1, errno EINTR.
> Expose a new lttng_poll_wait_interruptible API for this
> purpose.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> ---
>  src/common/compat/compat-epoll.c |  9 +++++----
>  src/common/compat/compat-poll.c  |  9 +++++----
>  src/common/compat/poll.h         | 12 ++++++++----
>  3 files changed, 18 insertions(+), 12 deletions(-)
> 
> diff --git a/src/common/compat/compat-epoll.c b/src/common/compat/compat-epoll.c
> index 6a781c7a..7108b717 100644
> --- a/src/common/compat/compat-epoll.c
> +++ b/src/common/compat/compat-epoll.c
> @@ -241,7 +241,7 @@ error:
>  /*
>   * Wait on epoll set. This is a blocking call of timeout value.
>   */
> -int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
> +int compat_epoll_wait(struct lttng_poll_event *events, int timeout, int interruptible)
>  {
>  	int ret;
>  	uint32_t new_size;
> @@ -273,10 +273,11 @@ int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
>  
>  	do {
>  		ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout);
> -	} while (ret == -1 && errno == EINTR);
> +	} while (!interruptible && ret == -1 && errno == EINTR);
>  	if (ret < 0) {
> -		/* At this point, every error is fatal */
> -		PERROR("epoll_wait");
> +		if (errno != EINTR) {
> +			PERROR("epoll_wait");
> +		}
>  		goto error;
>  	}
>  
> diff --git a/src/common/compat/compat-poll.c b/src/common/compat/compat-poll.c
> index 0220b278..dc507db5 100644
> --- a/src/common/compat/compat-poll.c
> +++ b/src/common/compat/compat-poll.c
> @@ -291,7 +291,7 @@ error:
>  /*
>   * Wait on poll() with timeout. Blocking call.
>   */
> -int compat_poll_wait(struct lttng_poll_event *events, int timeout)
> +int compat_poll_wait(struct lttng_poll_event *events, int timeout, int interruptible)
>  {
>  	int ret, active_fd_count;
>  	int idle_pfd_index = 0;
> @@ -320,10 +320,11 @@ int compat_poll_wait(struct lttng_poll_event *events, int timeout)
>  
>  	do {
>  		ret = poll(events->wait.events, events->wait.nb_fd, timeout);
> -	} while (ret == -1 && errno == EINTR);
> +	} while (!interruptible && ret == -1 && errno == EINTR);
>  	if (ret < 0) {
> -		/* At this point, every error is fatal */
> -		PERROR("poll wait");
> +		if (errno != EINTR) {
> +			PERROR("poll wait");
> +		}
>  		goto error;
>  	}
>  
> diff --git a/src/common/compat/poll.h b/src/common/compat/poll.h
> index d7020f36..da7d6970 100644
> --- a/src/common/compat/poll.h
> +++ b/src/common/compat/poll.h
> @@ -152,9 +152,11 @@ static inline int compat_glibc_epoll_create(int size, int flags)
>   * Wait on epoll set with the number of fd registered to the lttng_poll_event
>   * data structure (events).
>   */
> -extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
> +extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout, int interruptible);
>  #define lttng_poll_wait(events, timeout) \
> -	compat_epoll_wait(events, timeout)
> +	compat_epoll_wait(events, timeout, 0)
> +#define lttng_poll_wait_interruptible(events, timeout) \
> +	compat_epoll_wait(events, timeout, 1)
>  
>  /*
>   * Add a fd to the epoll set and resize the epoll_event structure if needed.
> @@ -336,9 +338,11 @@ extern int compat_poll_create(struct lttng_poll_event *events, int size);
>   * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
>   * structure.
>   */
> -extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
> +extern int compat_poll_wait(struct lttng_poll_event *events, int timeout, int interruptible);
>  #define lttng_poll_wait(events, timeout) \
> -	compat_poll_wait(events, timeout)
> +	compat_poll_wait(events, timeout, 0)
> +#define lttng_poll_wait_interruptible(events, timeout) \
> +	compat_poll_wait(events, timeout, 1)
>  
>  /*
>   * Add the fd to the pollfd structure. Resize if needed.
> -- 
> 2.17.1
>