From: fwu <redacted>
1. On ARM platform, "nohlt" can be used to prevent core from idle
process, returning immediately.
2. There are two interfaces, exported for other modules, named
"disable_hlt" and "enable_hlt" are used to enable/disable the
cpuidle mechanism by increasing/decreasing "hlt_counter".
Disable_hlt and enable_hlt are paired operation,
when you first call disable_hlt and then enable_hlt, the
semantics are right.
3. There is no obvious constraint to prevent user(driver/module)
code to prevent the case that enable_hlt is ahead of disable_hlt,
which is a fatal operation on kernel state change from user,
and there is no any WARNING or notification if the case happens
in current kernel code.
This patch aims to report BUG when the case happens, just like
what the kernel do when enable_irq is ahead of disable_irq.
Signed-off-by: fwu <redacted>
Signed-off-by: YiLu Mao <redacted>
Signed-off-by: Ning Jiang <redacted>
Change-Id: Iddacf45aec012bb663e130801727b4eb3d11436b
---
arch/arm/kernel/process.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 693b744..5bbd3be 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -70,6 +70,7 @@ EXPORT_SYMBOL(disable_hlt);
void enable_hlt(void)
{
hlt_counter--;
+ BUG_ON(hlt_counter < 0)
}
EXPORT_SYMBOL(enable_hlt);--
1.7.0.4
On Fri, 28 Sep 2012, Fan Wu wrote:
From: fwu <redacted>
1. On ARM platform, "nohlt" can be used to prevent core from idle
process, returning immediately.
2. There are two interfaces, exported for other modules, named
"disable_hlt" and "enable_hlt" are used to enable/disable the
cpuidle mechanism by increasing/decreasing "hlt_counter".
Disable_hlt and enable_hlt are paired operation,
when you first call disable_hlt and then enable_hlt, the
semantics are right.
3. There is no obvious constraint to prevent user(driver/module)
code to prevent the case that enable_hlt is ahead of disable_hlt,
which is a fatal operation on kernel state change from user,
and there is no any WARNING or notification if the case happens
in current kernel code.
This patch aims to report BUG when the case happens, just like
what the kernel do when enable_irq is ahead of disable_irq.
Signed-off-by: fwu <redacted>
Signed-off-by: YiLu Mao <redacted>
Signed-off-by: Ning Jiang <redacted>
This looks sensible to me.
Acked-by: Nicolas Pitre <redacted>
Change-Id: Iddacf45aec012bb663e130801727b4eb3d11436b
Please don't forget to strip that when submitting your patch to
Russell's patch system.
quoted hunk
---
arch/arm/kernel/process.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 693b744..5bbd3be 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -70,6 +70,7 @@ EXPORT_SYMBOL(disable_hlt);
void enable_hlt(void)
{
hlt_counter--;
+ BUG_ON(hlt_counter < 0)
}
EXPORT_SYMBOL(enable_hlt);--
1.7.0.4
On 09/29/2012 03:45 AM, Nicolas Pitre wrote:
On Fri, 28 Sep 2012, Fan Wu wrote:
quoted
From: fwu <redacted>
1. On ARM platform, "nohlt" can be used to prevent core from idle
process, returning immediately.
2. There are two interfaces, exported for other modules, named
"disable_hlt" and "enable_hlt" are used to enable/disable the
cpuidle mechanism by increasing/decreasing "hlt_counter".
Disable_hlt and enable_hlt are paired operation,
when you first call disable_hlt and then enable_hlt, the
semantics are right.
3. There is no obvious constraint to prevent user(driver/module)
code to prevent the case that enable_hlt is ahead of disable_hlt,
which is a fatal operation on kernel state change from user,
and there is no any WARNING or notification if the case happens
in current kernel code.
This patch aims to report BUG when the case happens, just like
what the kernel do when enable_irq is ahead of disable_irq.
Signed-off-by: fwu <redacted>
Signed-off-by: YiLu Mao <redacted>
Signed-off-by: Ning Jiang <redacted>
This looks sensible to me.
Acked-by: Nicolas Pitre <redacted>
quoted
Change-Id: Iddacf45aec012bb663e130801727b4eb3d11436b
Please don't forget to strip that when submitting your patch to
Russell's patch system.
quoted
---
arch/arm/kernel/process.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 693b744..5bbd3be 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -70,6 +70,7 @@ EXPORT_SYMBOL(disable_hlt);
void enable_hlt(void)
{
hlt_counter--;
+ BUG_ON(hlt_counter < 0)
}
EXPORT_SYMBOL(enable_hlt);--
1.7.0.4
Thanks a lot for reviewing the patch.
I'll remove that in the new patch version.
Thanks again.