ARM: entry: no need to increase preempt count for IRQ handlers

irq_enter() and irq_exit() already take care of the preempt_count
handling for interrupts, which increment and decrement the hardirq
bits of the preempt count.  So we can remove the preempt count handing
in our IRQ entry/exit assembly, like x86 did some 9 years ago.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 6855f6d..1e5f387 100644 (file)
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -220,16 +220,12 @@ __irq_svc:
 #ifdef CONFIG_TRACE_IRQFLAGS
        bl      trace_hardirqs_off
 #endif
-#ifdef CONFIG_PREEMPT
-       get_thread_info tsk
-       ldr     r8, [tsk, #TI_PREEMPT]          @ get preempt count
-       add     r7, r8, #1                      @ increment it
-       str     r7, [tsk, #TI_PREEMPT]
-#endif
 
        irq_handler
+
 #ifdef CONFIG_PREEMPT
-       str     r8, [tsk, #TI_PREEMPT]          @ restore preempt count
+       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
        movne   r0, #0                          @ force flags to 0
@@ -432,23 +428,8 @@ __irq_usr:
        bl      trace_hardirqs_off
 #endif
 
-       get_thread_info tsk
-#ifdef CONFIG_PREEMPT
-       ldr     r8, [tsk, #TI_PREEMPT]          @ get preempt count
-       add     r7, r8, #1                      @ increment it
-       str     r7, [tsk, #TI_PREEMPT]
-#endif
-
        irq_handler
-#ifdef CONFIG_PREEMPT
-       ldr     r0, [tsk, #TI_PREEMPT]
-       str     r8, [tsk, #TI_PREEMPT]
-       teq     r0, r7
- ARM(  strne   r0, [r0, -r0]   )
- THUMB(        movne   r0, #0          )
- THUMB(        strne   r0, [r0]        )
-#endif
-
+       get_thread_info tsk
        mov     why, #0
        b       ret_to_user_from_irq
  UNWIND(.fnend         )