lkml.org 
[lkml]   [2017]   [Sep]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] iommu/amd: Use raw_cpu_ptr() instead of get_cpu_ptr() for ->flush_queue
get_cpu_ptr() disables preemption and returns the ->flush_queue 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 in general
but on RT it does because the sleeping lock can't be accessed with
disabled preemption.

Cc: Joerg Roedel <joro@8bytes.org>
Cc: iommu@lists.linux-foundation.org
Reported-by: vinadhy@gmail.com
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/iommu/amd_iommu.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 4ad7e5e31943..943efbc08128 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1911,7 +1911,7 @@ static void queue_add(struct dma_ops_domain *dom,
pages = __roundup_pow_of_two(pages);
address >>= PAGE_SHIFT;

- queue = get_cpu_ptr(dom->flush_queue);
+ queue = raw_cpu_ptr(dom->flush_queue);
spin_lock_irqsave(&queue->lock, flags);

/*
@@ -1940,8 +1940,6 @@ static void queue_add(struct dma_ops_domain *dom,

if (atomic_cmpxchg(&dom->flush_timer_on, 0, 1) == 0)
mod_timer(&dom->flush_timer, jiffies + msecs_to_jiffies(10));
-
- put_cpu_ptr(dom->flush_queue);
}

static void queue_flush_timeout(unsigned long data)
--
2.14.1
\
 
 \ /
  Last update: 2017-09-06 12:35    [W:0.076 / U:1.616 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site