On 1/12/25 22:26, Phil Dennis-Jordan wrote:
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 <dw...@infradead.org>
Signed-off-by: Phil Dennis-Jordan <p...@philjordan.eu>
I'm worried that this breaks for exit() calls that happen within a
BQL-taken area (for example, anything that uses error_fatal) due to...
void bql_lock_impl(const char *file, int line)
{
QemuMutexLockFunc bql_lock_fn = qatomic_read(&bql_mutex_lock_func);
g_assert(!bql_locked()); // <--- this
bql_lock_fn(&bql, file, line);
set_bql_locked(true);
}
Paolo
