SYS-OSS/FRET-qemu
4
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

system/runstate: Fix regression, clarify BQL status of exit notifiers

Browse Source 
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 <dwmw@amazon.co.uk>
Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
This commit is contained in:
Phil Dennis-Jordan 2025-01-12 22:26:09 +01:00 committed by David Woodhouse
parent 8b44a3e39f
commit e7bc0204e5
2 changed files with 2 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/system/system.h
View File

@ -15,6 +15,7 @@ extern bool qemu_uuid_set;
const char *qemu_get_vm_name(void); const char *qemu_get_vm_name(void);
/* Exit notifiers will run with BQL held. */
void qemu_add_exit_notifier(Notifier *notify); void qemu_add_exit_notifier(Notifier *notify);
void qemu_remove_exit_notifier(Notifier *notify); void qemu_remove_exit_notifier(Notifier *notify);

1
system/runstate.c
View File

@ -850,6 +850,7 @@ void qemu_remove_exit_notifier(Notifier *notify)
static void qemu_run_exit_notifiers(void) static void qemu_run_exit_notifiers(void)
{ {
BQL_LOCK_GUARD();
notifier_list_notify(&exit_notifiers, NULL); notifier_list_notify(&exit_notifiers, NULL);
} }