[PATCH v2 2/2] eal/linux: handle interrupt epoll events

[Kevin Traynor]

Add handling for epoll error and disconnect conditions EPOLLERR,
EPOLLHUP and EPOLLRDHUP.

These events indicate that the interrupt file descriptor is in
an error state or there has been a hangup.

Only do this for interrupts that are read in eal. Interrupts that
are read outside eal should deal with different interrupt scenarios
appropriate to their functionality. e.g. virtio interrupt handling
has reconnect mechanisms for some cases.

Also, treat no bytes read as an error condition.

Bugzilla ID: 1873
Fixes: af75078fece3 ("first public release")
Cc: stable at dpdk.org

Signed-off-by: Kevin Traynor <ktraynor at redhat.com>
---
 lib/eal/linux/eal_interrupts.c | 67 ++++++++++++++++++++++------------
 1 file changed, 44 insertions(+), 23 deletions(-)

diff --git a/lib/eal/linux/eal_interrupts.c b/lib/eal/linux/eal_interrupts.c
index 9db978923a..68ca0f929e 100644
--- a/lib/eal/linux/eal_interrupts.c
+++ b/lib/eal/linux/eal_interrupts.c
@@ -887,4 +887,26 @@ rte_intr_disable(const struct rte_intr_handle *intr_handle)
 }
 
+static void
+eal_intr_source_remove_and_free(struct rte_intr_source *src)
+{
+	struct rte_intr_callback *cb, *next;
+
+	/* Remove the interrupt source */
+	rte_spinlock_lock(&intr_lock);
+	TAILQ_REMOVE(&intr_sources, src, next);
+	rte_spinlock_unlock(&intr_lock);
+
+	/* Free callbacks */
+	for (cb = TAILQ_FIRST(&src->callbacks); cb; cb = next) {
+		next = TAILQ_NEXT(cb, next);
+		TAILQ_REMOVE(&src->callbacks, cb, next);
+		free(cb);
+	}
+
+	/* Free the interrupt source */
+	rte_intr_instance_free(src->intr_handle);
+	free(src);
+}
+
 static int
 eal_intr_process_interrupts(struct epoll_event *events, int nfds)
@@ -952,4 +974,16 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
 
 		if (bytes_read > 0) {
+			/**
+			 * Check for epoll error or disconnect events for
+			 * interrupts that are read directly in eal.
+			 */
+			if (events[n].events & (EPOLLERR | EPOLLHUP | EPOLLRDHUP)) {
+				EAL_LOG(INFO, "Disconnect condition on fd %d "
+					"(events=0x%x), removing from epoll",
+					events[n].data.fd, events[n].events);
+				eal_intr_source_remove_and_free(src);
+				return -1;
+			}
+
 			/**
 			 * read out to clear the ready-to-be-read flag
@@ -957,5 +991,7 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
 			 */
 			bytes_read = read(events[n].data.fd, &buf, bytes_read);
-			if (bytes_read < 0) {
+			if (bytes_read > 0) {
+				call = true;
+			} else if (bytes_read < 0) {
 				if (errno == EINTR || errno == EWOULDBLOCK)
 					continue;
@@ -965,27 +1001,12 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
 					events[n].data.fd,
 					strerror(errno));
-				/*
-				 * The device is unplugged or buggy, remove
-				 * it as an interrupt source and return to
-				 * force the wait list to be rebuilt.
-				 */
-				rte_spinlock_lock(&intr_lock);
-				TAILQ_REMOVE(&intr_sources, src, next);
-				rte_spinlock_unlock(&intr_lock);
-
-				for (cb = TAILQ_FIRST(&src->callbacks); cb;
-							cb = next) {
-					next = TAILQ_NEXT(cb, next);
-					TAILQ_REMOVE(&src->callbacks, cb, next);
-					free(cb);
-				}
-				rte_intr_instance_free(src->intr_handle);
-				free(src);
-				return -1;
-			} else if (bytes_read == 0)
-				EAL_LOG(ERR, "Read nothing from file "
+			} else { /* bytes == 0 */
+				EAL_LOG(WARNING, "Read nothing from file "
 					"descriptor %d", events[n].data.fd);
-			else
-				call = true;
+			}
+			if (bytes_read <= 0) {
+				eal_intr_source_remove_and_free(src);
+				return -1;
+			}
 		}
 
-- 
2.52.0