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| author | Stephen Boyd <sboyd@codeaurora.org> | 2013-01-14 19:50:42 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-01-16 16:51:10 +0000 |
| commit | 568dca15aa2a0f4ddee255894ec393a159f13147 (patch) | |
| tree | f60bbd141dbda5325c1cb005920b43c08f03243e /arch/arm | |
| parent | 8a3a180d21793f2e4386b3cb61c48322564fc80a (diff) | |
| download | linux-rpi-568dca15aa2a0f4ddee255894ec393a159f13147.tar.gz linux-rpi-568dca15aa2a0f4ddee255894ec393a159f13147.tar.bz2 linux-rpi-568dca15aa2a0f4ddee255894ec393a159f13147.zip | |
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 <sboyd@codeaurora.org>
Reported-by: Patrik Kluba <pkluba@dension.com>
Tested-by: Patrik Kluba <pkluba@dension.com>
Cc: <stable@vger.kernel.org> # 2.6.30
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/vfp/entry.S | 6 | ||||
| -rw-r--r-- | 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 cc926c985981..323ce1a62bbf 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 ea0349f63586..dd5e56f95f3f 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 |