[PATCH v4 1/3] eal/linux: handle interrupt epoll events

[Kevin Traynor <ktraynor@redhat.com>]

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 disconnect/error events
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@dpdk.org

Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
Acked-by: David Marchand <david.marchand@redhat.com>
---
 lib/eal/linux/eal_interrupts.c | 72 ++++++++++++++++++++++------------
 1 file changed, 46 insertions(+), 26 deletions(-)

diff --git a/lib/eal/linux/eal_interrupts.c b/lib/eal/linux/eal_interrupts.c
index 9db978923a..f3f6bdd01d 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)
@@ -952,40 +974,38 @@ 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(ERR, "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
 			 * for epoll_wait.
 			 */
 			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;
 
-				EAL_LOG(ERR, "Error reading from file "
-					"descriptor %d: %s",
+				EAL_LOG(ERR, "Error reading from file descriptor %d: %s",
 					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);
+			} else {
+				EAL_LOG(ERR, "Read nothing from file descriptor %d",
+					events[n].data.fd);
+			}
+			if (bytes_read <= 0) {
+				eal_intr_source_remove_and_free(src);
 				return -1;
-			} else if (bytes_read == 0)
-				EAL_LOG(ERR, "Read nothing from file "
-					"descriptor %d", events[n].data.fd);
-			else
-				call = true;
+			}
 		}
 
-- 
2.53.0