Date: Thu, 22 Nov 2012 16:53:26 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: freebsd-acpi@FreeBSD.org Subject: [rfc] bind curthread to target cpu for _CST change notification Message-ID: <50AE3C66.2050207@FreeBSD.org>
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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);
--
Andriy Gapon
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