* [PATCH v3] cpu/hotplug: handle unbalanced hotplug enable/disable
@ 2016-06-10 6:43 Lianwei Wang
2016-06-20 6:55 ` Lianwei Wang
2016-09-02 18:43 ` [tip:smp/hotplug] cpu/hotplug: Handle " tip-bot for Lianwei Wang
0 siblings, 2 replies; 3+ messages in thread
From: Lianwei Wang @ 2016-06-10 6:43 UTC (permalink / raw)
To: tglx, peterz, oleg, mingo; +Cc: linux-kernel, linux-pm, Lianwei Wang
Currently it just print a warning message but did not
reset cpu_hotplug_disabled when the enable/disable is
unbalanced. The unbalanced enable/disable will lead
the cpu hotplug work abnormally.
Do nothing if an unablanced hotplug enable detected.
Signed-off-by: Lianwei Wang <lianwei.wang@gmail.com>
---
kernel/cpu.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 3e3f6e49eabb..5e26a3c64934 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -245,6 +245,14 @@ void cpu_hotplug_done(void)
cpuhp_lock_release();
}
+static void __cpu_hotplug_enable(void)
+{
+ if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
+ return;
+
+ cpu_hotplug_disabled--;
+}
+
/*
* Wait for currently running CPU hotplug operations to complete (if any) and
* disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
@@ -263,7 +271,7 @@ EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
- WARN_ON(--cpu_hotplug_disabled < 0);
+ __cpu_hotplug_enable();
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
@@ -1091,7 +1099,7 @@ void enable_nonboot_cpus(void)
/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
- WARN_ON(--cpu_hotplug_disabled < 0);
+ __cpu_hotplug_enable();
if (cpumask_empty(frozen_cpus))
goto out;
--
1.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] cpu/hotplug: handle unbalanced hotplug enable/disable
2016-06-10 6:43 [PATCH v3] cpu/hotplug: handle unbalanced hotplug enable/disable Lianwei Wang
@ 2016-06-20 6:55 ` Lianwei Wang
2016-09-02 18:43 ` [tip:smp/hotplug] cpu/hotplug: Handle " tip-bot for Lianwei Wang
1 sibling, 0 replies; 3+ messages in thread
From: Lianwei Wang @ 2016-06-20 6:55 UTC (permalink / raw)
To: Thomas Gleixner, Peter Zijlstra, Oleg Nesterov, Ingo Molnar
Cc: Linux Kernel Mailing List, linux-pm, Lianwei Wang
On Thu, Jun 9, 2016 at 11:43 PM, Lianwei Wang <lianwei.wang@gmail.com> wrote:
> Currently it just print a warning message but did not
> reset cpu_hotplug_disabled when the enable/disable is
> unbalanced. The unbalanced enable/disable will lead
> the cpu hotplug work abnormally.
>
> Do nothing if an unablanced hotplug enable detected.
>
> Signed-off-by: Lianwei Wang <lianwei.wang@gmail.com>
> ---
> kernel/cpu.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index 3e3f6e49eabb..5e26a3c64934 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -245,6 +245,14 @@ void cpu_hotplug_done(void)
> cpuhp_lock_release();
> }
>
> +static void __cpu_hotplug_enable(void)
> +{
> + if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
> + return;
> +
> + cpu_hotplug_disabled--;
> +}
> +
> /*
> * Wait for currently running CPU hotplug operations to complete (if any) and
> * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
> @@ -263,7 +271,7 @@ EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
> void cpu_hotplug_enable(void)
> {
> cpu_maps_update_begin();
> - WARN_ON(--cpu_hotplug_disabled < 0);
> + __cpu_hotplug_enable();
> cpu_maps_update_done();
> }
> EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
> @@ -1091,7 +1099,7 @@ void enable_nonboot_cpus(void)
>
> /* Allow everyone to use the CPU hotplug again */
> cpu_maps_update_begin();
> - WARN_ON(--cpu_hotplug_disabled < 0);
> + __cpu_hotplug_enable();
> if (cpumask_empty(frozen_cpus))
> goto out;
>
> --
> 1.9.1
>
Hi Thomas Gleixner,
Does this change look good to you?
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip:smp/hotplug] cpu/hotplug: Handle unbalanced hotplug enable/disable
2016-06-10 6:43 [PATCH v3] cpu/hotplug: handle unbalanced hotplug enable/disable Lianwei Wang
2016-06-20 6:55 ` Lianwei Wang
@ 2016-09-02 18:43 ` tip-bot for Lianwei Wang
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Lianwei Wang @ 2016-09-02 18:43 UTC (permalink / raw)
To: linux-tip-commits; +Cc: tglx, hpa, linux-kernel, lianwei.wang, mingo
Commit-ID: 01b41159066531cc8d664362ff0cd89dd137bbfa
Gitweb: http://git.kernel.org/tip/01b41159066531cc8d664362ff0cd89dd137bbfa
Author: Lianwei Wang <lianwei.wang@gmail.com>
AuthorDate: Thu, 9 Jun 2016 23:43:28 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 2 Sep 2016 20:37:17 +0200
cpu/hotplug: Handle unbalanced hotplug enable/disable
When cpu_hotplug_enable() is called unbalanced w/o a preceeding
cpu_hotplug_disable() the code emits a warning, but happily decrements the
disabled counter. This causes the next operations to malfunction.
Prevent the decrement and just emit a warning.
Signed-off-by: Lianwei Wang <lianwei.wang@gmail.com>
Cc: peterz@infradead.org
Cc: linux-pm@vger.kernel.org
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/1465541008-12476-1-git-send-email-lianwei.wang@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/cpu.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index c506485..c90f839 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -331,10 +331,17 @@ void cpu_hotplug_disable(void)
}
EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
+static void __cpu_hotplug_enable(void)
+{
+ if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
+ return;
+ cpu_hotplug_disabled--;
+}
+
void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
- WARN_ON(--cpu_hotplug_disabled < 0);
+ __cpu_hotplug_enable();
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
@@ -1160,7 +1167,7 @@ void enable_nonboot_cpus(void)
/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
- WARN_ON(--cpu_hotplug_disabled < 0);
+ __cpu_hotplug_enable();
if (cpumask_empty(frozen_cpus))
goto out;
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2016-06-10 6:43 [PATCH v3] cpu/hotplug: handle unbalanced hotplug enable/disable Lianwei Wang
2016-06-20 6:55 ` Lianwei Wang
2016-09-02 18:43 ` [tip:smp/hotplug] cpu/hotplug: Handle " tip-bot for Lianwei Wang
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