From 71b05ab5782aa1e38c016be6264a14f5650d2a87 Mon Sep 17 00:00:00 2001 From: Juan Quintela 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 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 RH-Acked-by: Peter Xu RH-Acked-by: Dr. David Alan Gilbert 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 Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Juan Quintela (cherry picked from commit 4d65a6216bfc44891ac298b74a6921d479805131) Signed-off-by: Danilo C. L. de Paula --- 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