Date: Sun, 25 Nov 2012 11:37:29 -0800 From: Sean Bruno <seanwbruno@gmail.com> To: Andriy Gapon <avg@FreeBSD.org> Cc: freebsd-acpi@FreeBSD.org Subject: Re: [rfc] bind curthread to target cpu for _CST change notification Message-ID: <1353872249.20189.3.camel@powernoodle> In-Reply-To: <50AE3C66.2050207@FreeBSD.org> References: <50AE3C66.2050207@FreeBSD.org>
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On Thu, 2012-11-22 at 16:53 +0200, Andriy Gapon wrote: > I would like to propose the following patch which should kill two birds with one > stone: > > - avoid race in acpi_cpu_cx_cst if more than one notifications occur in a rapid > succession for the same CPU and end up being concurrently handled by ACPI taskqeue > threads > - avoid race acpi_cpu_cx_cst and acpi_cpu_idle where the latter may access > resources being updated by the former > > What do you think? > > Index: sys/dev/acpica/acpi_cpu.c > =================================================================== > --- sys/dev/acpica/acpi_cpu.c (revision 242854) > +++ sys/dev/acpica/acpi_cpu.c (working copy) > @@ -1047,7 +1047,16 @@ > return; > > /* Update the list of Cx states. */ > + thread_lock(curthread); > + sched_bind(curthread, sc->cpu_pcpu->pc_cpuid); > + thread_unlock(curthread); > + critical_enter(); > acpi_cpu_cx_cst(sc); > + critical_exit(); > + thread_lock(curthread); > + sched_unbind(curthread); > + thread_unlock(curthread); > + > acpi_cpu_cx_list(sc); > > ACPI_SERIAL_BEGIN(cpu); > Ack. This looks appropriate to me. Sean
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