[libcamera-devel] [PATCH 2/4] libcamera: event_dispatcher_poll: Handle interrupted ppoll() calls

[Laurent Pinchart]

The ppoll() call can be interrupted if a signal is delivered. Handle the
EINTR error code gracefully by restarting the call. This fixes the
event-dispatcher test failure.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/libcamera/event_dispatcher_poll.cpp       | 58 +++++++++++--------
 src/libcamera/include/event_dispatcher_poll.h |  1 +
 2 files changed, 34 insertions(+), 25 deletions(-)

diff --git a/src/libcamera/event_dispatcher_poll.cpp b/src/libcamera/event_dispatcher_poll.cpp
index eefac54ca6da..6e0609c34ddc 100644
--- a/src/libcamera/event_dispatcher_poll.cpp
+++ b/src/libcamera/event_dispatcher_poll.cpp
@@ -128,32 +128,11 @@ void EventDispatcherPoll::processEvents()
 	for (auto notifier : notifiers_)
 		pollfds.push_back({ notifier.first, notifier.second.events(), 0 });
 
-	/* Compute the timeout. */
-	Timer *nextTimer = !timers_.empty() ? timers_.front() : nullptr;
-	struct timespec timeout;
-
-	if (nextTimer) {
-		clock_gettime(CLOCK_MONOTONIC, &timeout);
-		uint64_t now = timeout.tv_sec * 1000000000ULL + timeout.tv_nsec;
-
-		if (nextTimer->deadline() > now) {
-			uint64_t delta = nextTimer->deadline() - now;
-			timeout.tv_sec = delta / 1000000000ULL;
-			timeout.tv_nsec = delta % 1000000000ULL;
-		} else {
-			timeout.tv_sec = 0;
-			timeout.tv_nsec = 0;
-		}
-
-		LOG(Event, Debug)
-			<< "timeout " << timeout.tv_sec << "."
-			<< std::setfill('0') << std::setw(9)
-			<< timeout.tv_nsec;
-	}
-
 	/* Wait for events and process notifiers and timers. */
-	ret = ppoll(pollfds.data(), pollfds.size(),
-		    nextTimer ? &timeout : nullptr, nullptr);
+	do {
+		ret = poll(&pollfds);
+	} while (ret == -1 && errno == EINTR);
+
 	if (ret < 0) {
 		ret = -errno;
 		LOG(Event, Warning) << "poll() failed with " << strerror(-ret);
@@ -178,6 +157,35 @@ short EventDispatcherPoll::EventNotifierSetPoll::events() const
 	return events;
 }
 
+int EventDispatcherPoll::poll(std::vector<struct pollfd> *pollfds)
+{
+	/* Compute the timeout. */
+	Timer *nextTimer = !timers_.empty() ? timers_.front() : nullptr;
+	struct timespec timeout;
+
+	if (nextTimer) {
+		clock_gettime(CLOCK_MONOTONIC, &timeout);
+		uint64_t now = timeout.tv_sec * 1000000000ULL + timeout.tv_nsec;
+
+		if (nextTimer->deadline() > now) {
+			uint64_t delta = nextTimer->deadline() - now;
+			timeout.tv_sec = delta / 1000000000ULL;
+			timeout.tv_nsec = delta % 1000000000ULL;
+		} else {
+			timeout.tv_sec = 0;
+			timeout.tv_nsec = 0;
+		}
+
+		LOG(Event, Debug)
+			<< "timeout " << timeout.tv_sec << "."
+			<< std::setfill('0') << std::setw(9)
+			<< timeout.tv_nsec;
+	}
+
+	return ppoll(pollfds->data(), pollfds->size(),
+		     nextTimer ? &timeout : nullptr, nullptr);
+}
+
 void EventDispatcherPoll::processNotifiers(const std::vector<struct pollfd> &pollfds)
 {
 	static const struct {
diff --git a/src/libcamera/include/event_dispatcher_poll.h b/src/libcamera/include/event_dispatcher_poll.h
index a41926e11a11..ac3efde082b4 100644
--- a/src/libcamera/include/event_dispatcher_poll.h
+++ b/src/libcamera/include/event_dispatcher_poll.h
@@ -41,6 +41,7 @@ private:
 	std::map<int, EventNotifierSetPoll> notifiers_;
 	std::list<Timer *> timers_;
 
+	int poll(std::vector<struct pollfd> *pollfds);
 	void processNotifiers(const std::vector<struct pollfd> &pollfds);
 	void processTimers();
 };
-- 
Regards,

Laurent Pinchart