On Sunday 21 March 2010, Linus Torvalds wrote:
>
> On Sat, 20 Mar 2010, Rafael J. Wysocki wrote:
> >
> > The appended patch fixes the breakage for me too.
>
> Please don't use a 'goto' for something like this.
>
> > raw_spin_lock(&amd_nb_lock);
> >
> > + if (!cpuhw->amd_nb)
> > + goto unlock;
> > +
> > if (--cpuhw->amd_nb->refcnt == 0)
> > kfree(cpuhw->amd_nb);
> >
> > cpuhw->amd_nb = NULL;
> >
> > + unlock:
> > raw_spin_unlock(&amd_nb_lock);
> > }
>
> Just do
>
> raw_spin_lock(&amd_nb_lock);
> if (cpuhw->amd_nb) {
> if (!--cpuhw->amd_nb->refcnt)
> kfree(cpuhw->amd_nb);
> cpuhw->amd_nb = NULL;
> }
> raw_spin_unlock(&amd_nb_lock);
>
> instead. Much more readable.
>
> Let's keep 'goto' for cases where we have error returns that we don't want
> to nest, not trivial stuff like this.
OK
Rafael
---
From: Rafael J. Wysocki <rjw@xxxxxxx>
Subject: x86 / perf: Fix suspend to RAM on HP nx6325
Commit 3f6da3905398826d85731247e7fbcf53400c18bd
(perf: Rework and fix the arch CPU-hotplug hooks) broke suspend to
RAM on my HP nx6325 (and most likely on other AMD-based boxes too)
by allowing amd_pmu_cpu_offline() to be executed for CPUs that are
going offline as part of the suspend process. The problem is that
cpuhw->amd_nb may be NULL already, so the function should make sure
it's not NULL before accessing the object pointed to by it.
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---
arch/x86/kernel/cpu/perf_event_amd.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
Index: linux-2.6/arch/x86/kernel/cpu/perf_event_amd.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/perf_event_amd.c
+++ linux-2.6/arch/x86/kernel/cpu/perf_event_amd.c
@@ -348,10 +348,12 @@ static void amd_pmu_cpu_offline(int cpu)
raw_spin_lock(&amd_nb_lock);
- if (--cpuhw->amd_nb->refcnt == 0)
- kfree(cpuhw->amd_nb);
+ if (cpuhw->amd_nb) {
+ if (--cpuhw->amd_nb->refcnt == 0)
+ kfree(cpuhw->amd_nb);
- cpuhw->amd_nb = NULL;
+ cpuhw->amd_nb = NULL;
+ }
raw_spin_unlock(&amd_nb_lock);
}
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