[ 3.5.y.z extended stable ] Patch "ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not" has been added to staging queue
Herton Ronaldo Krzesinski
herton.krzesinski at canonical.com
Wed Jan 30 21:57:11 UTC 2013
This is a note to let you know that I have just added a patch titled
ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not
to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Herton
------
>From 920fa6b0e1f42b1e522e2114bc4bc2ce71a5a737 Mon Sep 17 00:00:00 2001
From: Stephen Boyd <sboyd at codeaurora.org>
Date: Mon, 14 Jan 2013 19:50:42 +0100
Subject: [PATCH] ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not
PREEMPT alone
commit 568dca15aa2a0f4ddee255894ec393a159f13147 upstream.
Patrik Kluba reports that the preempt count becomes invalid due
to the preempt_enable() call being unbalanced with a
preempt_disable() call in the vfp assembly routines. This happens
because preempt_enable() and preempt_disable() update preempt
counts under PREEMPT_COUNT=y but the vfp assembly routines do so
under PREEMPT=y. In a configuration where PREEMPT=n and
DEBUG_ATOMIC_SLEEP=y, PREEMPT_COUNT=y and so the preempt_enable()
call in VFP_bounce() keeps subtracting from the preempt count
until it goes negative.
Fix this by always using PREEMPT_COUNT to decided when to update
preempt counts in the ARM assembly code.
Signed-off-by: Stephen Boyd <sboyd at codeaurora.org>
Reported-by: Patrik Kluba <pkluba at dension.com>
Tested-by: Patrik Kluba <pkluba at dension.com>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
arch/arm/vfp/entry.S | 6 +++---
arch/arm/vfp/vfphw.S | 4 ++--
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm/vfp/entry.S b/arch/arm/vfp/entry.S
index cc926c9..323ce1a 100644
--- a/arch/arm/vfp/entry.S
+++ b/arch/arm/vfp/entry.S
@@ -22,7 +22,7 @@
@ IRQs disabled.
@
ENTRY(do_vfp)
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPT_COUNT
ldr r4, [r10, #TI_PREEMPT] @ get preempt count
add r11, r4, #1 @ increment it
str r11, [r10, #TI_PREEMPT]
@@ -35,7 +35,7 @@ ENTRY(do_vfp)
ENDPROC(do_vfp)
ENTRY(vfp_null_entry)
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPT_COUNT
get_thread_info r10
ldr r4, [r10, #TI_PREEMPT] @ get preempt count
sub r11, r4, #1 @ decrement it
@@ -53,7 +53,7 @@ ENDPROC(vfp_null_entry)
__INIT
ENTRY(vfp_testing_entry)
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPT_COUNT
get_thread_info r10
ldr r4, [r10, #TI_PREEMPT] @ get preempt count
sub r11, r4, #1 @ decrement it
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index 3a0efaa..6ff903e 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -167,7 +167,7 @@ vfp_hw_state_valid:
@ else it's one 32-bit instruction, so
@ always subtract 4 from the following
@ instruction address.
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPT_COUNT
get_thread_info r10
ldr r4, [r10, #TI_PREEMPT] @ get preempt count
sub r11, r4, #1 @ decrement it
@@ -191,7 +191,7 @@ look_for_VFP_exceptions:
@ not recognised by VFP
DBGSTR "not VFP"
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPT_COUNT
get_thread_info r10
ldr r4, [r10, #TI_PREEMPT] @ get preempt count
sub r11, r4, #1 @ decrement it
--
1.7.9.5
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