[PATCH 0/2] Trivial cleanups to EPOLL_CTL_DEL handling

[PATCH 0/2] Trivial cleanups to EPOLL_CTL_DEL handling

[David Gibson]

Ran across these small warts while looking at migration stuff.

David Gibson (2):
  tcp: Always pass NULL event with EPOLL_CTL_DEL
  util: Rename and make global vu_remove_watch()

 icmp.c       |  2 +-
 tap.c        |  2 +-
 tcp.c        |  4 ++--
 tcp_splice.c |  4 ++--
 udp_flow.c   |  2 +-
 util.c       | 10 ++++++++++
 util.h       |  1 +
 vhost_user.c | 21 +++++----------------
 vu_common.c  |  6 ++----
 9 files changed, 25 insertions(+), 27 deletions(-)

-- 
2.48.1

[PATCH 1/2] tcp: Always pass NULL event with EPOLL_CTL_DEL

[David Gibson]

In tcp_epoll_ctl() we pass an event pointer with EPOLL_CTL_DEL, even though
it will be ignored.  It's possible this was a workaround for pre-2.6.9
kernels which required a non-NULL pointer here, but we rely on the kernel
accepting NULL events for EPOLL_CTL_DEL in lots of other places.  Use
NULL instead for simplicity and consistency.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tcp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tcp.c b/tcp.c
index c89f3232..4eed82bf 100644
--- a/tcp.c
+++ b/tcp.c
@@ -468,9 +468,9 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 
 	if (conn->events == CLOSED) {
 		if (conn->in_epoll)
-			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->sock, &ev);
+			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->sock, NULL);
 		if (conn->timer != -1)
-			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->timer, &ev);
+			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->timer, NULL);
 		return 0;
 	}
 
-- 
@@ -468,9 +468,9 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 
 	if (conn->events == CLOSED) {
 		if (conn->in_epoll)
-			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->sock, &ev);
+			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->sock, NULL);
 		if (conn->timer != -1)
-			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->timer, &ev);
+			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->timer, NULL);
 		return 0;
 	}
 
-- 
2.48.1

[PATCH 2/2] util: Rename and make global vu_remove_watch()

[David Gibson]

vu_remove_watch() is used in vhost_user.c to remove an fd from the global
epoll set.  There's nothing really vhost user specific about it though,
so rename, move to util.c and use it in a bunch of places outside
vhost_user.c where it makes things marginally more readable.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 icmp.c       |  2 +-
 tap.c        |  2 +-
 tcp.c        |  4 ++--
 tcp_splice.c |  4 ++--
 udp_flow.c   |  2 +-
 util.c       | 10 ++++++++++
 util.h       |  1 +
 vhost_user.c | 21 +++++----------------
 vu_common.c  |  6 ++----
 9 files changed, 25 insertions(+), 27 deletions(-)

diff --git a/icmp.c b/icmp.c
index 143e93be..bcf498d2 100644
--- a/icmp.c
+++ b/icmp.c
@@ -150,7 +150,7 @@ unexpected:
 static void icmp_ping_close(const struct ctx *c,
 			    const struct icmp_ping_flow *pingf)
 {
-	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, pingf->sock, NULL);
+	epoll_del(c, pingf->sock);
 	close(pingf->sock);
 	flow_hash_remove(c, FLOW_SIDX(pingf, INISIDE));
 }
diff --git a/tap.c b/tap.c
index cd32a901..772648f9 100644
--- a/tap.c
+++ b/tap.c
@@ -1005,7 +1005,7 @@ void tap_sock_reset(struct ctx *c)
 		exit(EXIT_SUCCESS);
 
 	/* Close the connected socket, wait for a new connection */
-	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, c->fd_tap, NULL);
+	epoll_del(c, c->fd_tap);
 	close(c->fd_tap);
 	c->fd_tap = -1;
 	if (c->mode == MODE_VU)
diff --git a/tcp.c b/tcp.c
index 4eed82bf..77873815 100644
--- a/tcp.c
+++ b/tcp.c
@@ -468,9 +468,9 @@ static int tcp_epoll_ctl(const struct ctx *c, struct tcp_tap_conn *conn)
 
 	if (conn->events == CLOSED) {
 		if (conn->in_epoll)
-			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->sock, NULL);
+			epoll_del(c, conn->sock);
 		if (conn->timer != -1)
-			epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->timer, NULL);
+			epoll_del(c, conn->timer);
 		return 0;
 	}
 
diff --git a/tcp_splice.c b/tcp_splice.c
index 3a000ffa..5db1d62e 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -200,8 +200,8 @@ static void conn_flag_do(const struct ctx *c, struct tcp_splice_conn *conn,
 	}
 
 	if (flag == CLOSING) {
-		epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->s[0], NULL);
-		epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->s[1], NULL);
+		epoll_del(c, conn->s[0]);
+		epoll_del(c, conn->s[1]);
 	}
 }
 
diff --git a/udp_flow.c b/udp_flow.c
index 9fd7d06a..7fae81de 100644
--- a/udp_flow.c
+++ b/udp_flow.c
@@ -52,7 +52,7 @@ void udp_flow_close(const struct ctx *c, struct udp_flow *uflow)
 
 	if (uflow->s[TGTSIDE] >= 0) {
 		/* But the flow specific one needs to be removed */
-		epoll_ctl(c->epollfd, EPOLL_CTL_DEL, uflow->s[TGTSIDE], NULL);
+		epoll_del(c, uflow->s[TGTSIDE]);
 		close(uflow->s[TGTSIDE]);
 		uflow->s[TGTSIDE] = -1;
 	}
diff --git a/util.c b/util.c
index 11973c44..c7b09f08 100644
--- a/util.c
+++ b/util.c
@@ -837,3 +837,13 @@ void raw_random(void *buf, size_t buflen)
 	if (random_read < buflen)
 		die("Unexpected EOF on random data source");
 }
+
+/**
+ * epoll_del() - Remove a file descriptor from our passt epoll
+ * @c:		Execution context
+ * @fd:		File descriptor to remove
+ */
+void epoll_del(const struct ctx *c, int fd)
+{
+	epoll_ctl(c->epollfd, EPOLL_CTL_DEL, fd, NULL);
+}
diff --git a/util.h b/util.h
index d02333d5..800a28be 100644
--- a/util.h
+++ b/util.h
@@ -276,6 +276,7 @@ static inline bool mod_between(unsigned x, unsigned i, unsigned j, unsigned m)
 #define FPRINTF(f, ...)	(void)fprintf(f, __VA_ARGS__)
 
 void raw_random(void *buf, size_t buflen);
+void epoll_del(const struct ctx *c, int fd);
 
 /*
  * Starting from glibc 2.40.9000 and commit 25a5eb4010df ("string: strerror,
diff --git a/vhost_user.c b/vhost_user.c
index 6bf0dda8..bbbf504f 100644
--- a/vhost_user.c
+++ b/vhost_user.c
@@ -162,17 +162,6 @@ static void vmsg_close_fds(const struct vhost_user_msg *vmsg)
 		close(vmsg->fds[i]);
 }
 
-/**
- * vu_remove_watch() - Remove a file descriptor from our passt epoll
- * 		       file descriptor
- * @vdev:	vhost-user device
- * @fd:		file descriptor to remove
- */
-static void vu_remove_watch(const struct vu_dev *vdev, int fd)
-{
-	epoll_ctl(vdev->context->epollfd, EPOLL_CTL_DEL, fd, NULL);
-}
-
 /**
  * vmsg_set_reply_u64() - Set reply payload.u64 and clear request flags
  * 			  and fd_num
@@ -748,7 +737,7 @@ static bool vu_get_vring_base_exec(struct vu_dev *vdev,
 		vdev->vq[idx].call_fd = -1;
 	}
 	if (vdev->vq[idx].kick_fd != -1) {
-		vu_remove_watch(vdev, vdev->vq[idx].kick_fd);
+		epoll_del(vdev->context, vdev->vq[idx].kick_fd);
 		close(vdev->vq[idx].kick_fd);
 		vdev->vq[idx].kick_fd = -1;
 	}
@@ -816,7 +805,7 @@ static bool vu_set_vring_kick_exec(struct vu_dev *vdev,
 	vu_check_queue_msg_file(msg);
 
 	if (vdev->vq[idx].kick_fd != -1) {
-		vu_remove_watch(vdev, vdev->vq[idx].kick_fd);
+		epoll_del(vdev->context, vdev->vq[idx].kick_fd);
 		close(vdev->vq[idx].kick_fd);
 		vdev->vq[idx].kick_fd = -1;
 	}
@@ -1063,7 +1052,7 @@ static bool vu_set_device_state_fd_exec(struct vu_dev *vdev,
 		die("Invalide device_state_fd direction: %d", direction);
 
 	if (vdev->device_state_fd != -1) {
-		vu_remove_watch(vdev, vdev->device_state_fd);
+		epoll_del(vdev->context, vdev->device_state_fd);
 		close(vdev->device_state_fd);
 	}
 
@@ -1145,7 +1134,7 @@ void vu_cleanup(struct vu_dev *vdev)
 			vq->err_fd = -1;
 		}
 		if (vq->kick_fd != -1) {
-			vu_remove_watch(vdev, vq->kick_fd);
+			epoll_del(vdev->context, vq->kick_fd);
 			close(vq->kick_fd);
 			vq->kick_fd = -1;
 		}
@@ -1169,7 +1158,7 @@ void vu_cleanup(struct vu_dev *vdev)
 	vu_close_log(vdev);
 
 	if (vdev->device_state_fd != -1) {
-		vu_remove_watch(vdev, vdev->device_state_fd);
+		epoll_del(vdev->context, vdev->device_state_fd);
 		close(vdev->device_state_fd);
 		vdev->device_state_fd = -1;
 		vdev->device_state_result = -1;
diff --git a/vu_common.c b/vu_common.c
index f43d8ac4..2c12dca3 100644
--- a/vu_common.c
+++ b/vu_common.c
@@ -325,8 +325,7 @@ void vu_migrate(struct vu_dev *vdev, uint32_t events)
 		/* value to be returned by VHOST_USER_CHECK_DEVICE_STATE */
 		vdev->device_state_result = ret == -1 ? -1 : 0;
 		/* Closing the file descriptor signals the end of transfer */
-		epoll_ctl(vdev->context->epollfd, EPOLL_CTL_DEL,
-			  vdev->device_state_fd, NULL);
+		epoll_del(vdev->context, vdev->device_state_fd);
 		close(vdev->device_state_fd);
 		vdev->device_state_fd = -1;
 	} else if (events & EPOLLIN) {
@@ -346,8 +345,7 @@ void vu_migrate(struct vu_dev *vdev, uint32_t events)
 		debug("Closing migration channel");
 
 		/* The end of file signals the end of the transfer. */
-		epoll_ctl(vdev->context->epollfd, EPOLL_CTL_DEL,
-			  vdev->device_state_fd, NULL);
+		epoll_del(vdev->context, vdev->device_state_fd);
 		close(vdev->device_state_fd);
 		vdev->device_state_fd = -1;
 	}
-- 
@@ -325,8 +325,7 @@ void vu_migrate(struct vu_dev *vdev, uint32_t events)
 		/* value to be returned by VHOST_USER_CHECK_DEVICE_STATE */
 		vdev->device_state_result = ret == -1 ? -1 : 0;
 		/* Closing the file descriptor signals the end of transfer */
-		epoll_ctl(vdev->context->epollfd, EPOLL_CTL_DEL,
-			  vdev->device_state_fd, NULL);
+		epoll_del(vdev->context, vdev->device_state_fd);
 		close(vdev->device_state_fd);
 		vdev->device_state_fd = -1;
 	} else if (events & EPOLLIN) {
@@ -346,8 +345,7 @@ void vu_migrate(struct vu_dev *vdev, uint32_t events)
 		debug("Closing migration channel");
 
 		/* The end of file signals the end of the transfer. */
-		epoll_ctl(vdev->context->epollfd, EPOLL_CTL_DEL,
-			  vdev->device_state_fd, NULL);
+		epoll_del(vdev->context, vdev->device_state_fd);
 		close(vdev->device_state_fd);
 		vdev->device_state_fd = -1;
 	}
-- 
2.48.1