From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:37036) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gz5ng-0001zZ-5w for qemu-devel@nongnu.org; Wed, 27 Feb 2019 15:27:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gz5nc-0004HC-Fe for qemu-devel@nongnu.org; Wed, 27 Feb 2019 15:27:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47380) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gz5nY-0004DM-Im for qemu-devel@nongnu.org; Wed, 27 Feb 2019 15:27:26 -0500 From: Juan Quintela In-Reply-To: <20190227121052.GD2602@work-vm> (David Alan Gilbert's message of "Wed, 27 Feb 2019 12:10:52 +0000") References: <20190227121052.GD2602@work-vm> Reply-To: quintela@redhat.com Date: Wed, 27 Feb 2019 21:30:40 +0100 Message-ID: <87tvgprn2n.fsf@trasno.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] possible ahci/migrate fix List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: alex.bennee@linaro.org, qemu-devel@nongnu.org, peterx@redhat.com "Dr. David Alan Gilbert" wrote: > Hi Alex, > Can you see if the attached patch fixes the ahci/migrate failure you > see; it won't fail for me however mean I am to it. Reviewed-by: Juan Quintela It fixes the issue at point, and even if it is not a full solution (not sure if it is or not), it is a step in the right direction. Later, Juan. > > From f4c327d14d656d1c0f0e694d0efc6165493416f0 Mon Sep 17 00:00:00 2001 > From: "Dr. David Alan Gilbert" > Date: Wed, 27 Feb 2019 12:04:37 +0000 > Subject: [PATCH] migration: Cleanup during exit > > Currently we cleanup the migration object as we exit main after the > main_loop finishes; however if there's a migration running things > get messy and we can end up with the migration thread still trying > to access freed structures. > > We now take a ref to the object around the migration thread itself, > so the act of dropping the ref during exit doesn't cause us to lose > the state until the thread quits. > > Cancelling the migration during migration also tries to get the thread > to quit. > > We do this a bit earlier; so hopefully migration gets out of the way > before all the devices etc are freed. > > Signed-off-by: Dr. David Alan Gilbert > --- > migration/migration.c | 8 ++++++++ > vl.c | 7 ++++++- > 2 files changed, 14 insertions(+), 1 deletion(-) > > diff --git a/migration/migration.c b/migration/migration.c > index e44f77af02..f612313d09 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -126,6 +126,7 @@ static bool migration_object_check(MigrationState *ms, Error **errp); > static int migration_maybe_pause(MigrationState *s, > int *current_active_state, > int new_state); > +static void migrate_fd_cancel(MigrationState *s); > > void migration_object_init(void) > { > @@ -169,6 +170,11 @@ void migration_object_init(void) > > void migration_object_finalize(void) > { > + /* > + * Cancel the current migration - that will (eventually) > + * stop the migration using this structure > + */ > + migrate_fd_cancel(current_migration); > object_unref(OBJECT(current_migration)); > } > > @@ -3134,6 +3140,7 @@ static void *migration_thread(void *opaque) > > rcu_register_thread(); > > + object_ref(OBJECT(s)); > s->iteration_start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME); > > qemu_savevm_state_header(s->to_dst_file); > @@ -3230,6 +3237,7 @@ static void *migration_thread(void *opaque) > > trace_migration_thread_after_loop(); > migration_iteration_finish(s); > + object_unref(OBJECT(s)); > rcu_unregister_thread(); > return NULL; > } > diff --git a/vl.c b/vl.c > index 2f340686a7..c1920165f3 100644 > --- a/vl.c > +++ b/vl.c > @@ -4579,6 +4579,12 @@ int main(int argc, char **argv, char **envp) > > gdbserver_cleanup(); > > + /* > + * cleaning up the migration object cancels any existing migration > + * try to do this early so that it also stops using devices. > + */ > + migration_object_finalize(); > + > /* No more vcpu or device emulation activity beyond this point */ > vm_shutdown(); > > @@ -4594,7 +4600,6 @@ int main(int argc, char **argv, char **envp) > monitor_cleanup(); > qemu_chr_cleanup(); > user_creatable_cleanup(); > - migration_object_finalize(); > /* TODO: unref root container, check all devices are ok */ > > return 0;