[PATCH 1/3] watchdog: Disallow setting watchdog_thresh to -1

[PATCH 1/3] watchdog: Disallow setting watchdog_thresh to -1

[Li Zefan]

In old kernels, it's allowed to set softlockup_thresh to -1 or 0
to disable softlockup detection. However watchdog_thresh only
uses 0 to disable detection, and setting it to -1 just froze my
box and nothing I can do but reboot.

Signed-off-by: Li Zefan <lizefan@huawei.com>
---
 kernel/sysctl.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9edcf45..b0a1f99 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -120,7 +120,6 @@ extern int blk_iopoll_enabled;
 /* Constants used for minimum and  maximum */
 #ifdef CONFIG_LOCKUP_DETECTOR
 static int sixty = 60;
-static int neg_one = -1;
 #endif
 
 static int zero;
@@ -814,7 +813,7 @@ static struct ctl_table kern_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dowatchdog,
-		.extra1		= &neg_one,
+		.extra1		= &zero,
 		.extra2		= &sixty,
 	},
 	{
-- 
1.8.0.2

[PATCH 2/3] watchdog: Document watchdog_thresh sysctl

[Li Zefan]

Signed-off-by: Li Zefan <lizefan@huawei.com>
---
 Documentation/sysctl/kernel.txt | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index ccd4258..e8fabd6 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -76,6 +76,7 @@ show up in /proc/sys/kernel:
 - tainted
 - threads-max
 - unknown_nmi_panic
+- watchdog_thresh
 - version
 
 ==============================================================
@@ -648,3 +649,16 @@ that time, kernel debugging information is displayed on console.
 
 NMI switch that most IA32 servers have fires unknown NMI up, for
 example.  If a system hangs up, try pressing the NMI switch.
+
+==============================================================
+
+watchdog_thresh:
+
+This value can be used to control the frequency of hrtimer and NMI
+events and the soft and hard lockup thresholds. The default threshold
+is 10 seconds.
+
+The softlockup threshold is (2 * watchdog_thresh). Setting this
+tunable to zero will disable lockup detection altogether.
+
+==============================================================
-- 
1.8.0.2

Re: [PATCH 2/3] watchdog: Document watchdog_thresh sysctl

[Don Zickus]

On Fri, May 17, 2013 at 10:31:20AM +0800, Li Zefan wrote:
> 
> Signed-off-by: Li Zefan <lizefan@huawei.com>

Acked-by: Don Zickus <dzickus@redhat.com>

> ---
>  Documentation/sysctl/kernel.txt | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
> index ccd4258..e8fabd6 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -76,6 +76,7 @@ show up in /proc/sys/kernel:
>  - tainted
>  - threads-max
>  - unknown_nmi_panic
> +- watchdog_thresh
>  - version
>  
>  ==============================================================
> @@ -648,3 +649,16 @@ that time, kernel debugging information is displayed on console.
>  
>  NMI switch that most IA32 servers have fires unknown NMI up, for
>  example.  If a system hangs up, try pressing the NMI switch.
> +
> +==============================================================
> +
> +watchdog_thresh:
> +
> +This value can be used to control the frequency of hrtimer and NMI
> +events and the soft and hard lockup thresholds. The default threshold
> +is 10 seconds.
> +
> +The softlockup threshold is (2 * watchdog_thresh). Setting this
> +tunable to zero will disable lockup detection altogether.
> +
> +==============================================================
> -- 
> 1.8.0.2

[tip:perf/core] watchdog: Document watchdog_thresh sysctl

[tip-bot for Li Zefan]

Commit-ID:  08825c90af6e4bb902b3a51abb0ae6530199f682
Gitweb:     http://git.kernel.org/tip/08825c90af6e4bb902b3a51abb0ae6530199f682
Author:     Li Zefan <lizefan@huawei.com>
AuthorDate: Fri, 17 May 2013 10:31:20 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 May 2013 11:28:19 +0200

watchdog: Document watchdog_thresh sysctl

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/51959678.6000802@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 Documentation/sysctl/kernel.txt | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index ccd4258..e8fabd6 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -76,6 +76,7 @@ show up in /proc/sys/kernel:
 - tainted
 - threads-max
 - unknown_nmi_panic
+- watchdog_thresh
 - version
 
 ==============================================================
@@ -648,3 +649,16 @@ that time, kernel debugging information is displayed on console.
 
 NMI switch that most IA32 servers have fires unknown NMI up, for
 example.  If a system hangs up, try pressing the NMI switch.
+
+==============================================================
+
+watchdog_thresh:
+
+This value can be used to control the frequency of hrtimer and NMI
+events and the soft and hard lockup thresholds. The default threshold
+is 10 seconds.
+
+The softlockup threshold is (2 * watchdog_thresh). Setting this
+tunable to zero will disable lockup detection altogether.
+
+==============================================================

[PATCH 3/3] watchdog: Remove softlockup_thresh from Documentation

[Li Zefan]

The old softlockup detector has been replaced with new lockup
detector long ago.

Signed-off-by: Li Zefan <lizefan@huawei.com>
---
 Documentation/sysctl/kernel.txt | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index e8fabd6..bcff3f9 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -70,7 +70,6 @@ show up in /proc/sys/kernel:
 - shmall
 - shmmax                      [ sysv ipc ]
 - shmmni
-- softlockup_thresh
 - stop-a                      [ SPARC only ]
 - sysrq                       ==> Documentation/sysrq.txt
 - tainted
@@ -605,15 +604,6 @@ without users and with a dead originative process will be destroyed.
 
 ==============================================================
 
-softlockup_thresh:
-
-This value can be used to lower the softlockup tolerance threshold.  The
-default threshold is 60 seconds.  If a cpu is locked up for 60 seconds,
-the kernel complains.  Valid values are 1-60 seconds.  Setting this
-tunable to zero will disable the softlockup detection altogether.
-
-==============================================================
-
 tainted:
 
 Non-zero if the kernel has been tainted.  Numeric values, which
-- 
1.8.0.2

Re: [PATCH 3/3] watchdog: Remove softlockup_thresh from Documentation

[Don Zickus]

On Fri, May 17, 2013 at 10:31:35AM +0800, Li Zefan wrote:
> The old softlockup detector has been replaced with new lockup
> detector long ago.
> 
> Signed-off-by: Li Zefan <lizefan@huawei.com>

Acked-by: Don Zickus <dzickus@redhat.com>

> ---
>  Documentation/sysctl/kernel.txt | 10 ----------
>  1 file changed, 10 deletions(-)
> 
> diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
> index e8fabd6..bcff3f9 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -70,7 +70,6 @@ show up in /proc/sys/kernel:
>  - shmall
>  - shmmax                      [ sysv ipc ]
>  - shmmni
> -- softlockup_thresh
>  - stop-a                      [ SPARC only ]
>  - sysrq                       ==> Documentation/sysrq.txt
>  - tainted
> @@ -605,15 +604,6 @@ without users and with a dead originative process will be destroyed.
>  
>  ==============================================================
>  
> -softlockup_thresh:
> -
> -This value can be used to lower the softlockup tolerance threshold.  The
> -default threshold is 60 seconds.  If a cpu is locked up for 60 seconds,
> -the kernel complains.  Valid values are 1-60 seconds.  Setting this
> -tunable to zero will disable the softlockup detection altogether.
> -
> -==============================================================
> -
>  tainted:
>  
>  Non-zero if the kernel has been tainted.  Numeric values, which
> -- 
> 1.8.0.2

[tip:perf/core] watchdog: Remove softlockup_thresh from Documentation

[tip-bot for Li Zefan]

Commit-ID:  c0ffaf3655fab1909a920c8f30ba1722932d01bb
Gitweb:     http://git.kernel.org/tip/c0ffaf3655fab1909a920c8f30ba1722932d01bb
Author:     Li Zefan <lizefan@huawei.com>
AuthorDate: Fri, 17 May 2013 10:31:35 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 May 2013 11:28:20 +0200

watchdog: Remove softlockup_thresh from Documentation

The old softlockup detector has been replaced with new lockup
detector long ago.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/51959687.9090305@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 Documentation/sysctl/kernel.txt | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index e8fabd6..bcff3f9 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -70,7 +70,6 @@ show up in /proc/sys/kernel:
 - shmall
 - shmmax                      [ sysv ipc ]
 - shmmni
-- softlockup_thresh
 - stop-a                      [ SPARC only ]
 - sysrq                       ==> Documentation/sysrq.txt
 - tainted
@@ -605,15 +604,6 @@ without users and with a dead originative process will be destroyed.
 
 ==============================================================
 
-softlockup_thresh:
-
-This value can be used to lower the softlockup tolerance threshold.  The
-default threshold is 60 seconds.  If a cpu is locked up for 60 seconds,
-the kernel complains.  Valid values are 1-60 seconds.  Setting this
-tunable to zero will disable the softlockup detection altogether.
-
-==============================================================
-
 tainted:
 
 Non-zero if the kernel has been tainted.  Numeric values, which

Re: [PATCH 1/3] watchdog: Disallow setting watchdog_thresh to -1

[Don Zickus]

On Fri, May 17, 2013 at 10:31:04AM +0800, Li Zefan wrote:
> In old kernels, it's allowed to set softlockup_thresh to -1 or 0
> to disable softlockup detection. However watchdog_thresh only
> uses 0 to disable detection, and setting it to -1 just froze my
> box and nothing I can do but reboot.
> 
> Signed-off-by: Li Zefan <lizefan@huawei.com>

Acked-by: Don Zickus <dzickus@redhat.com>

[tip:perf/core] watchdog: Disallow setting watchdog_thresh to -1

[tip-bot for Li Zefan]

Commit-ID:  a6572f84c5b135d9b6df279ed3c8de028bd1edd9
Gitweb:     http://git.kernel.org/tip/a6572f84c5b135d9b6df279ed3c8de028bd1edd9
Author:     Li Zefan <lizefan@huawei.com>
AuthorDate: Fri, 17 May 2013 10:31:04 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 May 2013 11:28:18 +0200

watchdog: Disallow setting watchdog_thresh to -1

In old kernels, it's allowed to set softlockup_thresh to -1 or 0
to disable softlockup detection. However watchdog_thresh only
uses 0 to disable detection, and setting it to -1 just froze my
box and nothing I can do but reboot.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/51959668.9040106@huawei.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sysctl.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9edcf45..b0a1f99 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -120,7 +120,6 @@ extern int blk_iopoll_enabled;
 /* Constants used for minimum and  maximum */
 #ifdef CONFIG_LOCKUP_DETECTOR
 static int sixty = 60;
-static int neg_one = -1;
 #endif
 
 static int zero;
@@ -814,7 +813,7 @@ static struct ctl_table kern_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dowatchdog,
-		.extra1		= &neg_one,
+		.extra1		= &zero,
 		.extra2		= &sixty,
 	},
 	{