2017-07-20 17:26:16

by Victor Aoqui

Subject: [PATCH] powerpc/kernel: Avoid preemption check during iommu_range_alloc

Replaced __this_cpu_read function call by raw_cpu_read in
iommu_range_alloc function.
Preemption doesn't need to be disabled since any CPU can safely
use IOMMU pool.

Signed-off-by: Victor Aoqui <[email protected]>
---
arch/powerpc/kernel/iommu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 233ca3f..0e49a45 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -208,7 +208,7 @@ static unsigned long iommu_range_alloc(struct device *dev,
* We don't need to disable preemption here because any CPU can
* safely use any IOMMU pool.
*/
- pool_nr = __this_cpu_read(iommu_pool_hash) & (tbl->nr_pools - 1);
+ pool_nr = raw_cpu_read(iommu_pool_hash) & (tbl->nr_pools - 1);

if (largealloc)
pool = &(tbl->large_pool);
--
1.8.3.1

2017-08-07 10:41:58

by Michael Ellerman

Subject: Re: powerpc/kernel: Avoid preemption check during iommu_range_alloc

On Thu, 2017-07-20 at 17:26:06 UTC, victora wrote:
> Replaced __this_cpu_read function call by raw_cpu_read in
> iommu_range_alloc function.
> Preemption doesn't need to be disabled since any CPU can safely
> use IOMMU pool.
>
> Signed-off-by: Victor Aoqui <[email protected]>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/75f327c6b75715f3a090daeb33e050

cheers