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.
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