From 9f32e9bf43a6438c55f35d3c5ed1c378d0c715c4 Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 16 May 2019 15:08:50 -0400
Subject: [PATCH] epoll/poll compat: expose interruptible API
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

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@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/common/compat/compat-epoll.c | 11 +++++++----
 src/common/compat/compat-poll.c  | 10 ++++++----
 src/common/compat/poll.h         | 14 ++++++++++----
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/src/common/compat/compat-epoll.c b/src/common/compat/compat-epoll.c
index 6a781c7ae..794041726 100644
--- a/src/common/compat/compat-epoll.c
+++ b/src/common/compat/compat-epoll.c
@@ -23,6 +23,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <stdbool.h>
 
 #include <common/error.h>
 #include <common/defaults.h>
@@ -241,7 +242,8 @@ 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,
+		bool interruptible)
 {
 	int ret;
 	uint32_t new_size;
@@ -273,10 +275,11 @@ 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 254ce271e..4ea23c173 100644
--- a/src/common/compat/compat-poll.c
+++ b/src/common/compat/compat-poll.c
@@ -291,7 +291,8 @@ 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,
+		bool interruptible)
 {
 	int ret, active_fd_count;
 	int idle_pfd_index = 0;
@@ -320,10 +321,11 @@ 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 4b2fc5036..0b3cb3243 100644
--- a/src/common/compat/poll.h
+++ b/src/common/compat/poll.h
@@ -150,9 +150,12 @@ 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,
+		bool interruptible);
 #define lttng_poll_wait(events, timeout) \
-	compat_epoll_wait(events, timeout)
+	compat_epoll_wait(events, timeout, false)
+#define lttng_poll_wait_interruptible(events, timeout) \
+	compat_epoll_wait(events, timeout, true)
 
 /*
  * Add a fd to the epoll set and resize the epoll_event structure if needed.
@@ -334,9 +337,12 @@ 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,
+		bool interruptible);
 #define lttng_poll_wait(events, timeout) \
-	compat_poll_wait(events, timeout)
+	compat_poll_wait(events, timeout, false)
+#define lttng_poll_wait_interruptible(events, timeout) \
+	compat_poll_wait(events, timeout, true)
 
 /*
  * Add the fd to the pollfd structure. Resize if needed.
-- 
2.34.1