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authorJohn David Anglin <dave.anglin@bell.net>2016-11-24 20:06:32 -0500
committerHelge Deller <deller@gmx.de>2016-11-25 12:31:59 +0100
commitc0452fb9fb8f49c7d68ab9fa0ad092016be7b45f (patch)
tree18cdaf4195e895a6667959e73d2e80720a311cb5
parent43b1f6abd59063a088416a0df042b36450f91f75 (diff)
parisc: Fix race in pci-dma.c
We are still troubled by occasional random segmentation faults and memory memory corruption on SMP machines. The causes quite a few package builds to fail on the Debian buildd machines for parisc. When gcc-6 failed to build three times in a row, I looked again at the TLB related code. I found a couple of issues. This is the first. In general, we need to ensure page table updates and corresponding TLB purges are atomic. The attached patch fixes an instance in pci-dma.c where the page table update was not guarded by the TLB lock. Tested on rp3440 and c8000. So far, no further random segmentation faults have been observed. Signed-off-by: John David Anglin <dave.anglin@bell.net> Cc: <stable@vger.kernel.org> # v3.16+ Signed-off-by: Helge Deller <deller@gmx.de>
-rw-r--r--arch/parisc/kernel/pci-dma.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/parisc/kernel/pci-dma.c b/arch/parisc/kernel/pci-dma.c
index 02d9ed0f3949..494ff6e8c88a 100644
--- a/arch/parisc/kernel/pci-dma.c
+++ b/arch/parisc/kernel/pci-dma.c
@@ -95,8 +95,8 @@ static inline int map_pte_uncached(pte_t * pte,
if (!pte_none(*pte))
printk(KERN_ERR "map_pte_uncached: page already exists\n");
- set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC));
purge_tlb_start(flags);
+ set_pte(pte, __mk_pte(*paddr_ptr, PAGE_KERNEL_UNC));
pdtlb_kernel(orig_vaddr);
purge_tlb_end(flags);
vaddr += PAGE_SIZE;