Messages in this thread Patch in this message | | | Date | Fri, 25 Apr 2008 00:57:38 -0700 (PDT) | Subject | Re: [git pull] scheduler/misc fixes | From | David Miller <> |
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From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Fri, 25 Apr 2008 09:48:30 +0200
> c) there are 'IPI' handlers on SPARC64 that look like they can wake > the CPU from idle sleep but do not appear to call irq_enter() which > has the above patch's touch_softlock_watchdog() in its callchain. > > tl0_irq1: TRAP_IRQ(smp_call_function_client, 1) > tl0_irq2: TRAP_IRQ(smp_receive_signal_client, 2) > tl0_irq3: TRAP_IRQ(smp_penguin_jailcell, 3) > tl0_irq4: TRAP_IRQ(smp_new_mmu_context_version_client, 4) > > > > So the current working thesis is that the bug in a) hides a real problem > not quite fixed by b) and exploited by c).
The equivalent to smp_receive_signal_client() on x86 (smp_reschedule_interrupt) doesn't do an irq_enter() either.
However x86 does do an irq_enter() for smp_call_function() interrupt handling.
What is the rule in these cases?
Anyways, does the following patch fix the problem?
diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c index 524b889..bf4ef84 100644 --- a/arch/sparc64/kernel/smp.c +++ b/arch/sparc64/kernel/smp.c @@ -866,14 +866,21 @@ void smp_call_function_client(int irq, struct pt_regs *regs) void *info = call_data->info; clear_softint(1 << irq); + + irq_enter(); + + if (!call_data->wait) { + /* let initiator proceed after getting data */ + atomic_inc(&call_data->finished); + } + + func(info); + + irq_exit(); + if (call_data->wait) { /* let initiator proceed only after completion */ - func(info); - atomic_inc(&call_data->finished); - } else { - /* let initiator proceed after getting data */ atomic_inc(&call_data->finished); - func(info); } }
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