67 lines
2.4 KiB
Diff
67 lines
2.4 KiB
Diff
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Eric Blake <eblake@redhat.com>
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Date: Wed, 19 Jul 2017 18:01:59 +0200
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Subject: [PATCH] nbd: strict nbd_wr_syncv
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RH-Author: Eric Blake <eblake@redhat.com>
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Message-id: <20170719180202.23329-2-eblake@redhat.com>
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Patchwork-id: 75817
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O-Subject: [RHEV-7.4.z qemu-kvm-rhev PATCH 1/4] nbd: strict nbd_wr_syncv
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Bugzilla: 1467509
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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nbd_wr_syncv is called either from coroutine or from client negotiation
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code, when socket is in blocking mode. So, -EAGAIN is impossible.
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Furthermore, EAGAIN is confusing, as, what to read/write again? With
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EAGAIN as a return code we don't know how much data is already
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read or written by the function, so in case of EAGAIN the whole
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communication is broken.
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Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Message-Id: <20170516094533.6160-2-vsementsov@virtuozzo.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit f250a42ddaee042ad2eb02022a3ebd18fcf987de)
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Signed-off-by: Eric Blake <eblake@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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nbd/common.c | 11 ++++++-----
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1 file changed, 6 insertions(+), 5 deletions(-)
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diff --git a/nbd/common.c b/nbd/common.c
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index dccbb8e..4db45b3 100644
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--- a/nbd/common.c
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+++ b/nbd/common.c
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@@ -20,6 +20,10 @@
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#include "qapi/error.h"
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#include "nbd-internal.h"
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+/* nbd_wr_syncv
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+ * The function may be called from coroutine or from non-coroutine context.
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+ * When called from non-coroutine context @ioc must be in blocking mode.
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+ */
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ssize_t nbd_wr_syncv(QIOChannel *ioc,
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struct iovec *iov,
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size_t niov,
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@@ -42,11 +46,8 @@ ssize_t nbd_wr_syncv(QIOChannel *ioc,
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len = qio_channel_writev(ioc, local_iov, nlocal_iov, &local_err);
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}
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if (len == QIO_CHANNEL_ERR_BLOCK) {
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- if (qemu_in_coroutine()) {
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- qio_channel_yield(ioc, do_read ? G_IO_IN : G_IO_OUT);
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- } else {
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- return -EAGAIN;
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- }
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+ assert(qemu_in_coroutine());
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+ qio_channel_yield(ioc, do_read ? G_IO_IN : G_IO_OUT);
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continue;
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}
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if (len < 0) {
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--
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1.8.3.1
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