From 568dca15aa2a0f4ddee255894ec393a159f13147 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Mon, 14 Jan 2013 19:50:42 +0100 Subject: ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone 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 Reported-by: Patrik Kluba Tested-by: Patrik Kluba Cc: # 2.6.30 Signed-off-by: Russell King --- arch/arm/vfp/entry.S | 6 +++--- arch/arm/vfp/vfphw.S | 4 ++-- 2 files changed, 5 insertions(+), 5 deletions(-) (limited to 'arch/arm/vfp') diff --git a/arch/arm/vfp/entry.S b/arch/arm/vfp/entry.S index cc926c98598..323ce1a62bb 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 ea0349f6358..dd5e56f95f3 100644 --- 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 -- cgit v1.2.3-70-g09d2