From 3eae49ca8954f958b2001ab5643ef302cb7b67c7 Mon Sep 17 00:00:00 2001
From: cpw <cpw@sgi.com>
Date: Tue, 3 Dec 2013 17:15:30 -0600
Subject: [PATCH] x86/UV: Fix NULL pointer dereference in uv_flush_tlb_others()
if the 'nobau' boot option is used
The SGI UV tlb shootdown code panics the system with a NULL
pointer deference if 'nobau' is specified on the boot
commandline.
uv_flush_tlb_other() gets called for every flush, whether the
BAU is disabled or not. It should not be keeping the s_enters
statistic while the BAU is disabled.
The panic occurs because during initialization
init_per_cpu_tunables() does not set the bcp->statp pointer if
'nobau' was specified.
Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: <stable@vger.kernel.org> # 3.12.x
Link: http://lkml.kernel.org/r/E1VnzBi-0005yF-MU@eag09.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/platform/uv/tlb_uv.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 0f92173a12b6..efe4d7220397 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1070,12 +1070,13 @@ const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
unsigned long status;
bcp = &per_cpu(bau_control, cpu);
- stat = bcp->statp;
- stat->s_enters++;
if (bcp->nobau)
return cpumask;
+ stat = bcp->statp;
+ stat->s_enters++;
+
if (bcp->busy) {
descriptor_status =
read_lmmr(UVH_LB_BAU_SB_ACTIVATION_STATUS_0);
--
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