Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c4f3b63fe15b4629aa1ec163c95ab30423d0f76a
Commit:     c4f3b63fe15b4629aa1ec163c95ab30423d0f76a
Parent:     a5f2ce3c6024a5bb895647b6bd88ecae5001020a
Author:     Ravikiran G Thirumalai <[EMAIL PROTECTED]>
AuthorDate: Tue Oct 16 23:26:09 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed Oct 17 08:42:47 2007 -0700

    softlockup: add a /proc tuning parameter
    
    Control the trigger limit for softlockup warnings.  This is useful for
    debugging softlockups, by lowering the softlockup_thresh to identify
    possible softlockups earlier.
    
    This patch:
    1. Adds a sysctl softlockup_thresh with valid values of 1-60s
       (Higher value to disable false positives)
    2. Changes the softlockup printk to print the cpu softlockup time
    
    [EMAIL PROTECTED]: Fix various warnings and add definition of "two"]
    Signed-off-by: Ravikiran Thirumalai <[EMAIL PROTECTED]>
    Signed-off-by: Shai Fultheim <[EMAIL PROTECTED]>
    Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 Documentation/sysctl/kernel.txt |    8 ++++++++
 include/linux/sched.h           |    1 +
 kernel/softlockup.c             |    7 +++++--
 kernel/sysctl.c                 |   33 ++++++++++++++++++++++++++-------
 4 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 111fd28..8984a53 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -320,6 +320,14 @@ kernel.  This value defaults to SHMMAX.
 
 ==============================================================
 
+softlockup_thresh:
+
+This value can be used to lower the softlockup tolerance
+threshold. The default threshold is 10s.  If a cpu is locked up
+for 10s, the kernel complains.  Valid values are 1-60s.
+
+==============================================================
+
 tainted: 
 
 Non-zero if the kernel has been tainted.  Numeric values, which
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 59738ef..e643357 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -261,6 +261,7 @@ extern void softlockup_tick(void);
 extern void spawn_softlockup_task(void);
 extern void touch_softlockup_watchdog(void);
 extern void touch_all_softlockup_watchdogs(void);
+extern int softlockup_thresh;
 #else
 static inline void softlockup_tick(void)
 {
diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 72c2561..edeeef3 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -24,6 +24,7 @@ static DEFINE_PER_CPU(unsigned long, print_timestamp);
 static DEFINE_PER_CPU(struct task_struct *, watchdog_task);
 
 static int did_panic;
+int softlockup_thresh = 10;
 
 static int
 softlock_panic(struct notifier_block *this, unsigned long event, void *ptr)
@@ -104,13 +105,15 @@ void softlockup_tick(void)
                wake_up_process(per_cpu(watchdog_task, this_cpu));
 
        /* Warn about unreasonable 10+ seconds delays: */
-       if (now <= (touch_timestamp + 10))
+       if (now <= (touch_timestamp + softlockup_thresh))
                return;
 
        per_cpu(print_timestamp, this_cpu) = touch_timestamp;
 
        spin_lock(&print_lock);
-       printk(KERN_ERR "BUG: soft lockup detected on CPU#%d!\n", this_cpu);
+       printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %lus! [%s:%d]\n",
+                       this_cpu, now - touch_timestamp,
+                               current->comm, current->pid);
        if (regs)
                show_regs(regs);
        else
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 5e63de0..dde3d53 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -80,6 +80,19 @@ extern int maps_protect;
 extern int sysctl_stat_interval;
 extern int audit_argv_kb;
 
+/* Constants used for minimum and  maximum */
+#ifdef CONFIG_DETECT_SOFTLOCKUP
+static int one = 1;
+static int sixty = 60;
+#endif
+
+#ifdef CONFIG_MMU
+static int two = 2;
+#endif
+
+static int zero;
+static int one_hundred = 100;
+
 /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
 static int maxolduid = 65535;
 static int minolduid;
@@ -711,6 +724,19 @@ static ctl_table kern_table[] = {
                .proc_handler   = &proc_dointvec,
        },
 #endif
+#ifdef CONFIG_DETECT_SOFTLOCKUP
+       {
+               .ctl_name       = CTL_UNNUMBERED,
+               .procname       = "softlockup_thresh",
+               .data           = &softlockup_thresh,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = &proc_dointvec_minmax,
+               .strategy       = &sysctl_intvec,
+               .extra1         = &one,
+               .extra2         = &sixty,
+       },
+#endif
 #ifdef CONFIG_COMPAT
        {
                .ctl_name       = KERN_COMPAT_LOG,
@@ -757,13 +783,6 @@ static ctl_table kern_table[] = {
        { .ctl_name = 0 }
 };
 
-/* Constants for minimum and maximum testing in vm_table.
-   We use these as one-element integer vectors. */
-static int zero;
-static int two = 2;
-static int one_hundred = 100;
-
-
 static ctl_table vm_table[] = {
        {
                .ctl_name       = VM_OVERCOMMIT_MEMORY,
-
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