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From: Greg Kurz <groug@kaod.org>
To: qemu-devel@nongnu.org
Cc: "Daniel P . Berrangé" <berrange@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	"Greg Kurz" <groug@kaod.org>,
	virtio-fs@redhat.com, "Stefan Hajnoczi" <stefanha@redhat.com>,
	"Vivek Goyal" <vgoyal@redhat.com>
Subject: [PATCH v2 1/7] vhost-user: Drop misleading EAGAIN checks in slave_read()
Date: Fri, 12 Mar 2021 10:22:06 +0100	[thread overview]
Message-ID: <20210312092212.782255-2-groug@kaod.org> (raw)
In-Reply-To: <20210312092212.782255-1-groug@kaod.org>

slave_read() checks EAGAIN when reading or writing to the socket
fails. This gives the impression that the slave channel is in
non-blocking mode, which is certainly not the case with the current
code base. And the rest of the code isn't actually ready to cope
with non-blocking I/O.

Just drop the checks everywhere in this function for the sake of
clarity.

Signed-off-by: Greg Kurz <groug@kaod.org>
---
 hw/virtio/vhost-user.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 2fdd5daf74bb..6af9b43a7232 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1420,7 +1420,7 @@ static void slave_read(void *opaque)
 
     do {
         size = recvmsg(u->slave_fd, &msgh, 0);
-    } while (size < 0 && (errno == EINTR || errno == EAGAIN));
+    } while (size < 0 && errno == EINTR);
 
     if (size != VHOST_USER_HDR_SIZE) {
         error_report("Failed to read from slave.");
@@ -1452,7 +1452,7 @@ static void slave_read(void *opaque)
     /* Read payload */
     do {
         size = read(u->slave_fd, &payload, hdr.size);
-    } while (size < 0 && (errno == EINTR || errno == EAGAIN));
+    } while (size < 0 && errno == EINTR);
 
     if (size != hdr.size) {
         error_report("Failed to read payload from slave.");
@@ -1503,7 +1503,7 @@ static void slave_read(void *opaque)
 
         do {
             size = writev(u->slave_fd, iovec, ARRAY_SIZE(iovec));
-        } while (size < 0 && (errno == EINTR || errno == EAGAIN));
+        } while (size < 0 && errno == EINTR);
 
         if (size != VHOST_USER_HDR_SIZE + hdr.size) {
             error_report("Failed to send msg reply to slave.");
-- 
2.26.2



  reply	other threads:[~2021-03-12  9:25 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12  9:22 [PATCH v2 0/7] virtiofsd: Avoid potential deadlocks Greg Kurz
2021-03-12  9:22 ` Greg Kurz [this message]
2021-03-15 10:34   ` [PATCH v2 1/7] vhost-user: Drop misleading EAGAIN checks in slave_read() Stefan Hajnoczi
2021-03-12  9:22 ` [PATCH v2 2/7] vhost-user: Fix double-close on slave_read() error path Greg Kurz
2021-03-15 10:36   ` Stefan Hajnoczi
2021-03-12  9:22 ` [PATCH v2 3/7] vhost-user: Factor out duplicated slave_fd teardown code Greg Kurz
2021-03-15 10:36   ` Stefan Hajnoczi
2021-03-12  9:22 ` [PATCH v2 4/7] vhost-user: Convert slave channel to QIOChannelSocket Greg Kurz
2021-03-15 10:37   ` Stefan Hajnoczi
2021-03-12  9:22 ` [PATCH v2 5/7] vhost-user: Introduce nested event loop in vhost_user_read() Greg Kurz
2021-03-15 10:38   ` Stefan Hajnoczi
2021-03-12  9:22 ` [PATCH v2 6/7] vhost-user: Monitor slave channel " Greg Kurz
2021-03-15 12:20   ` Stefan Hajnoczi
2021-03-12  9:22 ` [PATCH v2 7/7] virtiofsd: Release vu_dispatch_lock when stopping queue Greg Kurz
2021-03-15 14:57   ` Dr. David Alan Gilbert

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