[cc +robin]
On Thu, 2 Nov 2017 18:33:50 +0100
Sebastian Andrzej Siewior <bige...@linutronix.de> wrote:
> On 2017-09-21 17:21:40 [+0200], Sebastian Andrzej Siewior wrote:
> > get_cpu_ptr() disabled preemption and returns the ->fq object of the
> > current CPU. raw_cpu_ptr() does the same except that it not disable
> > preemption which means the scheduler can move it to another CPU after it
> > obtained the per-CPU object.
> > In this case this is not bad because the data structure itself is
> > protected with a spin_lock. This change shouldn't matter however on RT
> > it does because the sleeping lock can't be accessed with disabled
> > preemption.
>
> Did this make to your tree Jörg?
Hi Sebastian,
Joerg is out on paternity leave through the end of the year, I'm
filling in in the interim. I hadn't looked for patches this far back,
so thanks for pointing it out. Robin, any comments? Thanks,
Alex
> > Cc: Joerg Roedel <j...@8bytes.org>
> > Cc: io...@lists.linux-foundation.org
> > Reported-by: vina...@gmail.com
> > Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
> > ---
> > On 2017-09-19 11:41:19 [+0200], Joerg Roedel wrote:
> > > Hi Sebastian,
> > Hi Jörg,
> >
> > > I moved the flushing to driver/iommu/iova.c to share it with the Intel
> > > IOMMU and possibly other drivers too, so this patch does no longer apply
> > > to v4.14-rc1. Can you update the patch to these changes?
> >
> > Sure.
> >
> > v1…v2: move the change from amd_iommu.c to iova.c
> >
> > drivers/iommu/iova.c | 4 +---
> > 1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> > index 33edfa794ae9..b30900025c62 100644
> > --- a/drivers/iommu/iova.c
> > +++ b/drivers/iommu/iova.c
> > @@ -570,7 +570,7 @@ void queue_iova(struct iova_domain *iovad,
> > unsigned long pfn, unsigned long pages,
> > unsigned long data)
> > {
> > - struct iova_fq *fq = get_cpu_ptr(iovad->fq);
> > + struct iova_fq *fq = raw_cpu_ptr(iovad->fq);
> > unsigned long flags;
> > unsigned idx;
> >
> > @@ -600,8 +600,6 @@ void queue_iova(struct iova_domain *iovad,
> > if (atomic_cmpxchg(&iovad->fq_timer_on, 0, 1) == 0)
> > mod_timer(&iovad->fq_timer,
> > jiffies + msecs_to_jiffies(IOVA_FQ_TIMEOUT));
> > -
> > - put_cpu_ptr(iovad->fq);
> > }
> > EXPORT_SYMBOL_GPL(queue_iova);
> >
> > --
> > 2.14.1
> >
>
> Sebastian
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