From 71b05ab5782aa1e38c016be6264a14f5650d2a87 Mon Sep 17 00:00:00 2001

From: Juan Quintela <quintela@redhat.com>

Date: Tue, 3 Mar 2020 14:51:35 +0000

Subject: [PATCH 03/18] migration: Make sure that we don't call write() in case

 of error

RH-Author: Juan Quintela <quintela@redhat.com>

Message-id: <20200303145143.149290-3-quintela@redhat.com>

Patchwork-id: 94113

O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH v2 02/10] migration: Make sure that we don't call write() in case of error

Bugzilla: 1738451

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

RH-Acked-by: Peter Xu <peterx@redhat.com>

RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

If we are exiting due to an error/finish/.... Just don't try to even

touch the channel with one IO operation.

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Signed-off-by: Juan Quintela <quintela@redhat.com>

(cherry picked from commit 4d65a6216bfc44891ac298b74a6921d479805131)

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 migration/ram.c | 25 +++++++++++++++++++++++++

 1 file changed, 25 insertions(+)

diff --git a/migration/ram.c b/migration/ram.c

index 65580e3..8c783b3 100644

--- a/migration/ram.c

+++ b/migration/ram.c

@@ -899,6 +899,12 @@ struct {

     uint64_t packet_num;

     /* send channels ready */

     QemuSemaphore channels_ready;

+    /*

+     * Have we already run terminate threads.  There is a race when it

+     * happens that we got one error while we are exiting.

+     * We will use atomic operations.  Only valid values are 0 and 1.

+     */

+    int exiting;

 } *multifd_send_state;

 /*

@@ -927,6 +933,10 @@ static int multifd_send_pages(RAMState *rs)

     MultiFDPages_t *pages = multifd_send_state->pages;

     uint64_t transferred;

+    if (atomic_read(&multifd_send_state->exiting)) {

+        return -1;

+    }

+

     qemu_sem_wait(&multifd_send_state->channels_ready);

     for (i = next_channel;; i = (i + 1) % migrate_multifd_channels()) {

         p = &multifd_send_state->params[i];

@@ -1008,6 +1018,16 @@ static void multifd_send_terminate_threads(Error *err)

         }

     }

+    /*

+     * We don't want to exit each threads twice.  Depending on where

+     * we get the error, or if there are two independent errors in two

+     * threads at the same time, we can end calling this function

+     * twice.

+     */

+    if (atomic_xchg(&multifd_send_state->exiting, 1)) {

+        return;

+    }

+

     for (i = 0; i < migrate_multifd_channels(); i++) {

         MultiFDSendParams *p = &multifd_send_state->params[i];

@@ -1117,6 +1137,10 @@ static void *multifd_send_thread(void *opaque)

     while (true) {

         qemu_sem_wait(&p->sem);

+

+        if (atomic_read(&multifd_send_state->exiting)) {

+            break;

+        }

         qemu_mutex_lock(&p->mutex);

         if (p->pending_job) {

@@ -1225,6 +1249,7 @@ int multifd_save_setup(void)

     multifd_send_state->params = g_new0(MultiFDSendParams, thread_count);

     multifd_send_state->pages = multifd_pages_init(page_count);

     qemu_sem_init(&multifd_send_state->channels_ready, 0);

+    atomic_set(&multifd_send_state->exiting, 0);

     for (i = 0; i < thread_count; i++) {

         MultiFDSendParams *p = &multifd_send_state->params[i];

-- 

1.8.3.1