| Message ID | 20250112212609.17996-1-phil@philjordan.eu (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | system/runstate: Fix regression, clarify BQL status of exit notifiers | expand |
diff --git a/include/system/system.h b/include/system/system.h index 5364ad4f27..0cbb43ec30 100644 --- a/include/system/system.h +++ b/include/system/system.h @@ -15,6 +15,7 @@ extern bool qemu_uuid_set; const char *qemu_get_vm_name(void); +/* Exit notifiers will run with BQL held. */ void qemu_add_exit_notifier(Notifier *notify); void qemu_remove_exit_notifier(Notifier *notify); diff --git a/system/runstate.c b/system/runstate.c index 3a8fe866bc..272801d307 100644 --- a/system/runstate.c +++ b/system/runstate.c @@ -850,6 +850,7 @@ void qemu_remove_exit_notifier(Notifier *notify) static void qemu_run_exit_notifiers(void) { + BQL_LOCK_GUARD(); notifier_list_notify(&exit_notifiers, NULL); }
By changing the way the main QEMU event loop is invoked, I inadvertently changed the BQL status of exit notifiers: some of them implicitly assumed they would be called with the BQL held; the BQL is however not held during the exit(status) call in qemu_default_main(). Instead of attempting to ensuring we always call exit() from the BQL - including any transitive calls - this change adds a BQL lock guard to qemu_run_exit_notifiers, ensuring the BQL will always be held in the exit notifiers. Additionally, the BQL promise is now documented at the qemu_{add,remove}_exit_notifier() declarations. Fixes: f5ab12caba4f ("ui & main loop: Redesign of system-specific main thread event handling") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2771 Reported-by: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu> --- include/system/system.h | 1 + system/runstate.c | 1 + 2 files changed, 2 insertions(+)