This is a note to let you know that I've just added the patch titled
ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone
to the 3.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-7627-1-predicate-preempt-logic-on-preemp_count-not-preempt-alone.patch
and it can be found in the queue-3.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 568dca15aa2a0f4ddee255894ec393a159f13147 Mon Sep 17 00:00:00 2001
From: Stephen Boyd <[email protected]>
Date: Mon, 14 Jan 2013 19:50:42 +0100
Subject: ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone
From: Stephen Boyd <[email protected]>
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 <[email protected]>
Reported-by: Patrik Kluba <[email protected]>
Tested-by: Patrik Kluba <[email protected]>
Signed-off-by: Russell King <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/arm/vfp/entry.S | 6 +++---
arch/arm/vfp/vfphw.S | 4 ++--
2 files changed, 5 insertions(+), 5 deletions(-)
--- 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
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -168,7 +168,7 @@ 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
@@ -192,7 +192,7 @@ 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
Patches currently in stable-queue which might be from [email protected] are
queue-3.7/arm-7627-1-predicate-preempt-logic-on-preemp_count-not-preempt-alone.patch
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