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[PATCH v1 1/1] QIOChannelSocket: Fix zero-copy send so socket flush work
From: |
Leonardo Bras |
Subject: |
[PATCH v1 1/1] QIOChannelSocket: Fix zero-copy send so socket flush works |
Date: |
Wed, 8 Jun 2022 15:18:09 -0300 |
Somewhere between v6 and v7 the of the zero-copy-send patchset a crucial
part of the flushing mechanism got missing: incrementing zero_copy_queued.
Without that, the flushing interface becomes a no-op, and there is no
garantee the buffer is really sent.
This can go as bad as causing a corruption in RAM during migration.
Fixes: 2bc58ffc2926 ("QIOChannelSocket: Implement io_writev zero copy flag &
io_flush for CONFIG_LINUX")
Reported-by: 徐闯 <xuchuangxclwt@bytedance.com>
Signed-off-by: Leonardo Bras <leobras@redhat.com>
---
io/channel-socket.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/io/channel-socket.c b/io/channel-socket.c
index dc9c165de1..ca4cae930f 100644
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -554,6 +554,7 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
size_t fdsize = sizeof(int) * nfds;
struct cmsghdr *cmsg;
int sflags = 0;
+ bool zero_copy_enabled = false;
memset(control, 0, CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS));
@@ -581,6 +582,7 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
#ifdef QEMU_MSG_ZEROCOPY
if (flags & QIO_CHANNEL_WRITE_FLAG_ZERO_COPY) {
sflags = MSG_ZEROCOPY;
+ zero_copy_enabled = true;
}
#endif
@@ -592,21 +594,24 @@ static ssize_t qio_channel_socket_writev(QIOChannel *ioc,
return QIO_CHANNEL_ERR_BLOCK;
case EINTR:
goto retry;
-#ifdef QEMU_MSG_ZEROCOPY
case ENOBUFS:
- if (sflags & MSG_ZEROCOPY) {
+ if (zero_copy_enabled) {
error_setg_errno(errp, errno,
"Process can't lock enough memory for using
MSG_ZEROCOPY");
return -1;
}
break;
-#endif
}
error_setg_errno(errp, errno,
"Unable to write to socket");
return -1;
}
+
+ if (zero_copy_enabled) {
+ sioc->zero_copy_queued++;
+ }
+
return ret;
}
#else /* WIN32 */
--
2.36.1
- [PATCH v1 1/1] QIOChannelSocket: Fix zero-copy send so socket flush works,
Leonardo Bras <=