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Subject: arm-preempt-lazy-support.patch
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 31 Oct 2012 12:04:11 +0100
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/arm/Kconfig | 1 +
arch/arm/include/asm/thread_info.h | 3 +++
arch/arm/kernel/asm-offsets.c | 1 +
arch/arm/kernel/entry-armv.S | 13 +++++++++++--
arch/arm/kernel/signal.c | 3 ++-
5 files changed, 18 insertions(+), 3 deletions(-)
Index: linux-stable/arch/arm/Kconfig
===================================================================
--- linux-stable.orig/arch/arm/Kconfig
+++ linux-stable/arch/arm/Kconfig
@@ -50,6 +50,7 @@ config ARM
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select DCACHE_WORD_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && !CPU_BIG_ENDIAN
+ select HAVE_PREEMPT_LAZY
help
The ARM series is a line of low-power-consumption RISC chip designs
licensed by ARM Ltd and targeted at embedded applications and
Index: linux-stable/arch/arm/include/asm/thread_info.h
===================================================================
--- linux-stable.orig/arch/arm/include/asm/thread_info.h
+++ linux-stable/arch/arm/include/asm/thread_info.h
@@ -50,6 +50,7 @@ struct cpu_context_save {
struct thread_info {
unsigned long flags; /* low level flags */
int preempt_count; /* 0 => preemptable, <0 => bug */
+ int preempt_lazy_count; /* 0 => preemptable, <0 => bug */
mm_segment_t addr_limit; /* address limit */
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
@@ -146,6 +147,7 @@ extern int vfp_restore_user_hwstate(stru
#define TIF_SIGPENDING 0
#define TIF_NEED_RESCHED 1
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
+#define TIF_NEED_RESCHED_LAZY 3
#define TIF_SYSCALL_TRACE 8
#define TIF_SYSCALL_AUDIT 9
#define TIF_POLLING_NRFLAG 16
@@ -158,6 +160,7 @@ extern int vfp_restore_user_hwstate(stru
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
+#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
Index: linux-stable/arch/arm/kernel/asm-offsets.c
===================================================================
--- linux-stable.orig/arch/arm/kernel/asm-offsets.c
+++ linux-stable/arch/arm/kernel/asm-offsets.c
@@ -50,6 +50,7 @@ int main(void)
BLANK();
DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count));
+ DEFINE(TI_PREEMPT_LAZY, offsetof(struct thread_info, preempt_lazy_count));
DEFINE(TI_ADDR_LIMIT, offsetof(struct thread_info, addr_limit));
DEFINE(TI_TASK, offsetof(struct thread_info, task));
DEFINE(TI_EXEC_DOMAIN, offsetof(struct thread_info, exec_domain));
Index: linux-stable/arch/arm/kernel/entry-armv.S
===================================================================
--- linux-stable.orig/arch/arm/kernel/entry-armv.S
+++ linux-stable/arch/arm/kernel/entry-armv.S
@@ -216,11 +216,18 @@ __irq_svc:
#ifdef CONFIG_PREEMPT
get_thread_info tsk
ldr r8, [tsk, #TI_PREEMPT] @ get preempt count
- ldr r0, [tsk, #TI_FLAGS] @ get flags
teq r8, #0 @ if preempt count != 0
+ bne 1f @ return from exeption
+ ldr r0, [tsk, #TI_FLAGS] @ get flags
+ tst r0, #_TIF_NEED_RESCHED @ if NEED_RESCHED is set
+ blne svc_preempt @ preempt!
+
+ ldr r8, [tsk, #TI_PREEMPT_LAZY] @ get preempt lazy count
+ teq r8, #0 @ if preempt lazy count != 0
movne r0, #0 @ force flags to 0
- tst r0, #_TIF_NEED_RESCHED
+ tst r0, #_TIF_NEED_RESCHED_LAZY
blne svc_preempt
+1:
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
@@ -240,6 +247,8 @@ svc_preempt:
1: bl preempt_schedule_irq @ irq en/disable is done inside
ldr r0, [tsk, #TI_FLAGS] @ get new tasks TI_FLAGS
tst r0, #_TIF_NEED_RESCHED
+ bne 1b
+ tst r0, #_TIF_NEED_RESCHED_LAZY
moveq pc, r8 @ go again
b 1b
#endif
Index: linux-stable/arch/arm/kernel/signal.c
===================================================================
--- linux-stable.orig/arch/arm/kernel/signal.c
+++ linux-stable/arch/arm/kernel/signal.c
@@ -639,7 +639,8 @@ asmlinkage int
do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
do {
- if (likely(thread_flags & _TIF_NEED_RESCHED)) {
+ if (likely(thread_flags & (_TIF_NEED_RESCHED |
+ _TIF_NEED_RESCHED_LAZY))) {
schedule();
} else {
if (unlikely(!user_mode(regs)))
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