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| author | Paolo Bonzini <pbonzini@redhat.com> | 2014-06-27 16:31:07 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-07-09 18:17:08 +0200 |
| commit | 30e5210a706ca6b52cbefa8b71e40ae614ffd6e5 (patch) | |
| tree | b5714afa10c11c42b4d190711f39468ff66e5ee1 /hw/watchdog | |
| parent | f7f152458e953690f1c8025f507a26d554f6ee4d (diff) | |
| download | qemu-30e5210a706ca6b52cbefa8b71e40ae614ffd6e5.tar.gz | |
watchdog: fix deadlock with -watchdog-action pause
qemu_clock_enable says:
/* Disabling the clock will wait for related timerlists to stop
* executing qemu_run_timers. Thus, this functions should not
* be used from the callback of a timer that is based on @clock.
* Doing so would cause a deadlock.
*/
and it indeed does: vm_stop uses qemu_clock_enable on QEMU_CLOCK_VIRTUAL
and watchdogs are based on QEMU_CLOCK_VIRTUAL, and we get a deadlock.
Use qemu_system_vmstop_request_prepare()/qemu_system_vmstop_request()
instead; yet another alternative could be a BH.
I checked other occurrences of vm_stop and they should not have this
problem. RUN_STATE_IO_ERROR could in principle (it depends on the
code in the drivers) but it has been fixed by commit 2bd3bce, "block:
asynchronously stop the VM on I/O errors", 2014-06-05.
Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'hw/watchdog')
| -rw-r--r-- | hw/watchdog/watchdog.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/hw/watchdog/watchdog.c b/hw/watchdog/watchdog.c index 9f607d42bb..c307f9b57e 100644 --- a/hw/watchdog/watchdog.c +++ b/hw/watchdog/watchdog.c @@ -122,8 +122,12 @@ void watchdog_perform_action(void) exit(0); case WDT_PAUSE: /* same as 'stop' command in monitor */ + /* In a timer callback, when vm_stop calls qemu_clock_enable + * you would get a deadlock. Bypass the problem. + */ + qemu_system_vmstop_request_prepare(); qapi_event_send_watchdog(WATCHDOG_EXPIRATION_ACTION_PAUSE, &error_abort); - vm_stop(RUN_STATE_WATCHDOG); + qemu_system_vmstop_request(RUN_STATE_WATCHDOG); break; case WDT_DEBUG: |