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From: Roman Kagan <rvkagan@yandex-team.ru>
To: qemu-devel@nongnu.org
Cc: "Kevin Wolf" <kwolf@redhat.com>,
	qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
	"Raphael Norwitz" <raphael.norwitz@nutanix.com>,
	"Hanna Reitz" <hreitz@redhat.com>,
	yc-core@yandex-team.ru,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>
Subject: [PATCH 02/10] chardev/char-socket: tcp_chr_recv: don't clobber errno
Date: Thu, 11 Nov 2021 18:33:46 +0300	[thread overview]
Message-ID: <20211111153354.18807-3-rvkagan@yandex-team.ru> (raw)
In-Reply-To: <20211111153354.18807-1-rvkagan@yandex-team.ru>

tcp_chr_recv communicates the specific error condition to the caller via
errno.  However, after setting it, it may call into some system calls or
library functions which can clobber the errno.

Avoid this by moving the errno assignment to the end of the function.

Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
---
 chardev/char-socket.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 836cfa0bc2..90054ce58c 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -346,13 +346,6 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, size_t len)
                                      NULL);
     }
 
-    if (ret == QIO_CHANNEL_ERR_BLOCK) {
-        errno = EAGAIN;
-        ret = -1;
-    } else if (ret == -1) {
-        errno = EIO;
-    }
-
     if (msgfds_num) {
         /* close and clean read_msgfds */
         for (i = 0; i < s->read_msgfds_num; i++) {
@@ -381,6 +374,13 @@ static ssize_t tcp_chr_recv(Chardev *chr, char *buf, size_t len)
 #endif
     }
 
+    if (ret == QIO_CHANNEL_ERR_BLOCK) {
+        errno = EAGAIN;
+        ret = -1;
+    } else if (ret == -1) {
+        errno = EIO;
+    }
+
     return ret;
 }
 
-- 
2.33.1



  parent reply	other threads:[~2021-11-11 15:39 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-11 15:33 [PATCH 00/10] vhost: stick to -errno error return convention Roman Kagan
2021-11-11 15:33 ` [PATCH 01/10] vhost-user-blk: reconnect on any error during realize Roman Kagan
2021-11-11 17:52   ` Kevin Wolf
2021-11-12  7:39     ` Roman Kagan
2021-11-12 11:37       ` Kevin Wolf
2021-11-12 19:59         ` Roman Kagan
2021-11-29 22:15           ` Raphael Norwitz
2021-11-29 22:17   ` Raphael Norwitz
2021-11-11 15:33 ` Roman Kagan [this message]
2021-11-12  8:27   ` [PATCH 02/10] chardev/char-socket: tcp_chr_recv: don't clobber errno Marc-André Lureau
2021-11-11 15:33 ` [PATCH 03/10] chardev/char-socket: tcp_chr_sync_read: " Roman Kagan
2021-11-12  8:28   ` Marc-André Lureau
2021-11-11 15:33 ` [PATCH 04/10] chardev/char-fe: don't allow EAGAIN from blocking read Roman Kagan
2021-11-12  8:24   ` Marc-André Lureau
2021-11-12 19:04     ` Roman Kagan
2021-11-11 15:33 ` [PATCH 05/10] vhost-backend: avoid overflow on memslots_limit Roman Kagan
2021-11-11 17:59   ` Philippe Mathieu-Daudé
2021-11-12  7:46     ` Roman Kagan
2021-11-12  9:56       ` Daniel P. Berrangé
2021-11-12 11:10         ` Roman Kagan
2021-11-11 15:33 ` [PATCH 06/10] vhost-backend: stick to -errno error return convention Roman Kagan
2021-11-11 18:00   ` Philippe Mathieu-Daudé
2021-11-11 15:33 ` [PATCH 07/10] vhost-vdpa: " Roman Kagan
2021-11-11 15:33 ` [PATCH 08/10] vhost-user: " Roman Kagan
2021-11-11 15:33 ` [PATCH 09/10] vhost: " Roman Kagan
2021-11-11 15:33 ` [PATCH 10/10] vhost-user-blk: propagate error return from generic vhost Roman Kagan
2021-11-29 22:37   ` Raphael Norwitz
2021-11-11 20:14 ` [PATCH 00/10] vhost: stick to -errno error return convention Michael S. Tsirkin
2021-11-12  8:04   ` Roman Kagan
2021-11-28 21:47 ` Michael S. Tsirkin
2021-11-29 21:44   ` Roman Kagan
2022-01-06  9:57 ` Michael S. Tsirkin

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