On 20/04/21 17:32, Peter Xu wrote:
On Tue, Apr 20, 2021 at 10:37:39AM -0400, Peter Xu wrote:
On Tue, Apr 20, 2021 at 04:16:14AM -0400, Paolo Bonzini wrote:
The main thread could start to send SIG_IPI at any time, even before signal
blocked on vcpu thread. Therefore, start the vcpu thread with the signal
blocked.
Without this patch, on very busy cores the dirty_log_test could fail directly
on receiving a SIGUSR1 without a handler (when vcpu runs far slower than main).
Reported-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Yes, indeed better! :)
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
I just remembered one thing: this will avoid program quits, but still we'll get
the signal missing.
In what sense the signal will be missing? As long as the thread exists,
the signal will be accepted (but not delivered because it is blocked);
it will then be delivered on the first KVM_RUN.
Paolo
From that pov I slightly prefer the old patch. However
not a big deal so far as only dirty ring uses SIG_IPI, so there's always ring
full which will just delay the kick. It's just we need to remember this when we
extend IPI to non-dirty-ring tests as the kick is prone to be lost then.
Thanks,
