83 lines
3.2 KiB
Diff
83 lines
3.2 KiB
Diff
From 52e2456a41678f29a67e4b7cd4d7ee20e5298bc0 Mon Sep 17 00:00:00 2001
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From: Fabiano Rosas <farosas@suse.de>
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Date: Mon, 18 Sep 2023 14:28:18 -0300
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Subject: [PATCH 04/13] migration: Fix possible race when shutting down
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to_dst_file
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Peter Xu <peterx@redhat.com>
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RH-MergeRequest: 203: migration: Fix race that dest preempt thread close too early
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RH-Jira: RHEL-11219
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Acked-by: Leonardo Brás <leobras@redhat.com>
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RH-Commit: [4/8] 99b9ce27c4477b9630cedfb02a534f8c490ab1eb (peterx/qemu-kvm)
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It's not safe to call qemu_file_shutdown() on the to_dst_file without
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first checking for the file's presence under the lock. The cleanup of
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this file happens at postcopy_pause() and migrate_fd_cleanup() which
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are not necessarily running in the same thread as migrate_fd_cancel().
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Reviewed-by: Peter Xu <peterx@redhat.com>
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Signed-off-by: Fabiano Rosas <farosas@suse.de>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-ID: <20230918172822.19052-5-farosas@suse.de>
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(cherry picked from commit 7478fb0df914f0a5ab551ff74b1df62dd250500e)
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Signed-off-by: Peter Xu <peterx@redhat.com>
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---
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migration/migration.c | 18 +++++++++++-------
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1 file changed, 11 insertions(+), 7 deletions(-)
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diff --git a/migration/migration.c b/migration/migration.c
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index 517b3e04d2..169e6bdce8 100644
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--- a/migration/migration.c
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+++ b/migration/migration.c
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@@ -1246,7 +1246,7 @@ static void migrate_fd_error(MigrationState *s, const Error *error)
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static void migrate_fd_cancel(MigrationState *s)
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{
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int old_state ;
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- QEMUFile *f = migrate_get_current()->to_dst_file;
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+
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trace_migrate_fd_cancel();
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WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) {
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@@ -1272,11 +1272,13 @@ static void migrate_fd_cancel(MigrationState *s)
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* If we're unlucky the migration code might be stuck somewhere in a
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* send/write while the network has failed and is waiting to timeout;
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* if we've got shutdown(2) available then we can force it to quit.
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- * The outgoing qemu file gets closed in migrate_fd_cleanup that is
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- * called in a bh, so there is no race against this cancel.
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*/
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- if (s->state == MIGRATION_STATUS_CANCELLING && f) {
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- qemu_file_shutdown(f);
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+ if (s->state == MIGRATION_STATUS_CANCELLING) {
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+ WITH_QEMU_LOCK_GUARD(&s->qemu_file_lock) {
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+ if (s->to_dst_file) {
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+ qemu_file_shutdown(s->to_dst_file);
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+ }
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+ }
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}
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if (s->state == MIGRATION_STATUS_CANCELLING && s->block_inactive) {
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Error *local_err = NULL;
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@@ -1520,12 +1522,14 @@ void qmp_migrate_pause(Error **errp)
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{
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MigrationState *ms = migrate_get_current();
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MigrationIncomingState *mis = migration_incoming_get_current();
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- int ret;
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+ int ret = 0;
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if (ms->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
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/* Source side, during postcopy */
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qemu_mutex_lock(&ms->qemu_file_lock);
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- ret = qemu_file_shutdown(ms->to_dst_file);
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+ if (ms->to_dst_file) {
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+ ret = qemu_file_shutdown(ms->to_dst_file);
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+ }
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qemu_mutex_unlock(&ms->qemu_file_lock);
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if (ret) {
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error_setg(errp, "Failed to pause source migration");
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--
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2.39.3
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