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kernel: add MIPS kernel fix for an uninitialized CPU map

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Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 48956
This commit is contained in:
Felix Fietkau 2016-03-07 21:00:46 +00:00
parent 46c7d0d1ab
commit b9f52b6b86
1 changed files with 31 additions and 0 deletions
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target/linux/generic/patches-4.4/103-MIPS-smp.c-Fix-uninitialised-temp_foreign_map.patch Normal file
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@ -0,0 +1,31 @@
From: James Hogan <james.hogan@imgtec.com>
Date: Fri, 4 Mar 2016 10:10:51 +0000
Subject: [PATCH] MIPS: smp.c: Fix uninitialised temp_foreign_map
When calculate_cpu_foreign_map() recalculates the cpu_foreign_map
cpumask it uses the local variable temp_foreign_map without initialising
it to zero. Since the calculation only ever sets bits in this cpumask
any existing bits at that memory location will remain set and find their
way into cpu_foreign_map too. This could potentially lead to cache
operations suboptimally doing smp calls to multiple VPEs in the same
core, even though the VPEs share primary caches.
Therefore initialise temp_foreign_map using cpumask_clear() before use.
Fixes: cccf34e9411c ("MIPS: c-r4k: Fix cache flushing for MT cores")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
---
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -121,6 +121,7 @@ static inline void calculate_cpu_foreign
cpumask_t temp_foreign_map;
/* Re-calculate the mask */
+ cpumask_clear(&temp_foreign_map);
for_each_online_cpu(i) {
core_present = 0;
for_each_cpu(k, &temp_foreign_map)