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From dd0ab2d849f8a93fe54a29eedb8a536fbc42fe5d Mon Sep 17 00:00:00 2001
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From: Amit Shah <amit.shah@redhat.com>
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Date: Tue, 8 Oct 2013 06:13:07 +0200
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Subject: [PATCH 08/11] char: remove watch callback on chardev detach from frontend
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RH-Author: Amit Shah <amit.shah@redhat.com>
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Message-id: <0044db8c12053fd38667200f350132d7a3485cde.1381210228.git.amit.shah@redhat.com>
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Patchwork-id: 54729
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O-Subject: [RHEL7 qemu-kvm PATCH 3/3] char: remove watch callback on chardev detach from frontend
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Bugzilla: 1007222
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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If a frontend device releases the chardev (via unplug), the chr handlers
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are set to NULL via qdev's exit callbacks invoking
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qemu_chr_add_handlers(). If the chardev had a pending operation, a
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callback will be invoked, which will try to access data in the
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just-released frontend, causing a segfault.
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Ensure the callbacks are disabled when frontends release chardevs.
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This was seen when a virtio-serial port was unplugged when heavy
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guest->host IO was in progress (causing a callback to be registered).
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In the window in which the throttling was active, unplugging ports
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caused a qemu segfault.
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https://bugzilla.redhat.com/show_bug.cgi?id=985205
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CC: <qemu-stable@nongnu.org>
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Reported-by: Sibiao Luo <sluo@redhat.com>
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Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
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Signed-off-by: Amit Shah <amit.shah@redhat.com>
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---
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qemu-char.c | 3 +++
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1 file changed, 3 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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qemu-char.c | 3 +++
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1 files changed, 3 insertions(+), 0 deletions(-)
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diff --git a/qemu-char.c b/qemu-char.c
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index 8d46f98..2fb876c 100644
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--- a/qemu-char.c
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+++ b/qemu-char.c
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@@ -195,6 +195,8 @@ void qemu_chr_fe_printf(CharDriverState *s, const char *fmt, ...)
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va_end(ap);
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}
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+static void remove_fd_in_watch(CharDriverState *chr);
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+
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void qemu_chr_add_handlers(CharDriverState *s,
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IOCanReadHandler *fd_can_read,
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IOReadHandler *fd_read,
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@@ -205,6 +207,7 @@ void qemu_chr_add_handlers(CharDriverState *s,
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if (!opaque && !fd_can_read && !fd_read && !fd_event) {
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fe_open = 0;
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+ remove_fd_in_watch(s);
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} else {
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fe_open = 1;
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}
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--
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1.7.1
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