From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: x86: Kick VCPU outside PIC lock again Date: Wed, 24 Feb 2010 11:48:04 +0200 Message-ID: <4B84F5D4.5020202@redhat.com> References: <20100217135901.331576359@linutronix.de> <4B842A1F.50601@siemens.com> <4B84F466.2080009@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Thomas Gleixner , KVM , Gleb Natapov , RT , Linux Kernel Mailing List To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:31034 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755651Ab0BXJsM (ORCPT ); Wed, 24 Feb 2010 04:48:12 -0500 In-Reply-To: <4B84F466.2080009@siemens.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 02/24/2010 11:41 AM, Jan Kiszka wrote: > Thomas Gleixner wrote: > >> On Tue, 23 Feb 2010, Jan Kiszka wrote: >> >> >>> Thomas Gleixner wrote: >>> >>>> The i8254/i8259 locks need to be real spinlocks on preempt-rt. Convert >>>> them to raw_spinlock. No change for !RT kernels. >>>> >>> Doesn't fly for -rt anymore: pic_irq_update runs under this raw lock and >>> calls kvm_vcpu_kick which tries to wake_up some thread -> scheduling >>> while atomic. >>> >> Hmm, a wakeup itself is fine. Is that code waking a wake queue ? >> > Yes, it's a wake queue. > So what's the core issue? Is the lock_t in the wait_queue a sleeping mutex? > This restores the deferred VCPU kicking before 956f97cf. We need this > over -rt as wake_up* requires non-atomic context in this configuration. > > Seems sane, will apply once I understand why the current code fails. -- error compiling committee.c: too many arguments to function