From: Keir Fraser Date: Tue, 10 Aug 2010 14:47:41 +0000 (+0100) Subject: xen/x86: eliminate nesting of run-queue locks inside xtime_lock X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=41d2cd91037ff8e31032fabbf632f5e566bda4a1;p=legacy%2Flinux-2.6.18-xen.git xen/x86: eliminate nesting of run-queue locks inside xtime_lock From: Zdenek Salvet According to Debian bug 591362 this has been causing problems. While no proof was given that the inverse lock order does actually occur anywhere (with interrupts enabled), it is plain unnecessary to take the risk. Signed-off-by: Jan Beulich Acked-by: Ian Campbell --- diff --git a/arch/i386/kernel/time-xen.c b/arch/i386/kernel/time-xen.c index 60292c4e..0b31fc56 100644 --- a/arch/i386/kernel/time-xen.c +++ b/arch/i386/kernel/time-xen.c @@ -654,6 +654,7 @@ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) s64 delta, delta_cpu, stolen, blocked; u64 sched_time; unsigned int i, cpu = smp_processor_id(); + int schedule_clock_was_set_work = 0; struct shadow_time_info *shadow = &per_cpu(shadow_time, cpu); struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu); @@ -715,12 +716,14 @@ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) if (shadow_tv_version != HYPERVISOR_shared_info->wc_version) { update_wallclock(); - if (keventd_up()) - schedule_work(&clock_was_set_work); + schedule_clock_was_set_work = 1; } write_sequnlock(&xtime_lock); + if (schedule_clock_was_set_work && keventd_up()) + schedule_work(&clock_was_set_work); + /* * Account stolen ticks. * HACK: Passing NULL to account_steal_time()