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

[Mathieu Desnoyers]

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