[PATCH 01/01] arm: fix a preempt_count() corruption for CONFIG_PREEMPT=n

["Patrik, Kluba" <pkluba@dension.com>]

[-- Attachment #1: Type: text/plain, Size: 286 bytes --]

Hi All,

After a hard days' work, I've managed to track down a ghost causing
sporadic kernel warnings and system crashes. The patch applies for the
HEAD of linux-stable. I don't know how to create and submit patches
correctly, and hope that somebody will pick it up...

Regards,
Patrik

[-- Attachment #2: 0001-arm-fix-a-preempt_count-corruption-for-CONFIG_PREEMP.patch --]
[-- Type: text/x-patch, Size: 1012 bytes --]

>From 4dd31e88a2715389e5ac198dcf00b48b4f148ea6 Mon Sep 17 00:00:00 2001
From: Patrik Kluba <pkluba@dension.com>
Date: Fri, 14 Dec 2012 14:36:27 +0100
Subject: [PATCH] arm: fix a preempt_count() corruption for CONFIG_PREEMPT=n

All the preempt-disabling assembly code is under CONFIG_PREEMPT,
while VFP_bounce calls preempt_enable() uncoditionally, leading to
a preempt_count() corruption (gets set to 0xffffffff). Fix the
imbalance by adding #ifdef CONFIG_PREEMPT before preempt_enable().
---
 arch/arm/vfp/vfpmodule.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 3b44e0d..2184f7e 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -428,7 +428,10 @@ void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
 	if (exceptions)
 		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
  exit:
+#ifdef CONFIG_PREEMPT
 	preempt_enable();
+#endif
+	return;
 }
 
 static void vfp_enable(void *unused)
-- 
1.7.10.4