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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