[patch 3/4] dynamic configurable kref debugging

From: Akinobu Mita
Date: Mon Apr 24 2006 - 04:34:40 EST


This patch makes kref-debugging dynamically configurable
by sysctl kernel.kref_debug

Signed-off-by: Akinobu Mita <mita@xxxxxxxxxxxxxxxx>

Documentation/sysctl/kernel.txt | 8 ++++++++
include/linux/sysctl.h | 1 +
kernel/sysctl.c | 14 ++++++++++++++
lib/kref.c | 9 +++++++++
4 files changed, 32 insertions(+)

Index: 2.6-git/lib/kref.c
===================================================================
--- 2.6-git.orig/lib/kref.c
+++ 2.6-git/lib/kref.c
@@ -24,13 +24,22 @@ void kref_init(struct kref *kref)
}

#ifdef CONFIG_DEBUG_KREF
+
+int kref_debug = 1;
+
static void kref_get_debug_check(struct kref *kref)
{
+ if (!kref_debug)
+ return;
+
BUG_ON(!atomic_read(&kref->refcount));
}
static void kref_put_debug_check(struct kref *kref,
void (*release)(struct kref *kref))
{
+ if (!kref_debug)
+ return;
+
BUG_ON(atomic_read(&kref->refcount) < 1);
BUG_ON(release == NULL);
BUG_ON(release == (void (*)(struct kref *))kfree);
Index: 2.6-git/include/linux/sysctl.h
===================================================================
--- 2.6-git.orig/include/linux/sysctl.h
+++ 2.6-git/include/linux/sysctl.h
@@ -148,6 +148,7 @@ enum
KERN_SPIN_RETRY=70, /* int: number of spinlock retries */
KERN_ACPI_VIDEO_FLAGS=71, /* int: flags for setting up video after ACPI sleep */
KERN_IA64_UNALIGNED=72, /* int: ia64 unaligned userland trap enable */
+ KERN_KREF_DEBUG=73, /* int: kref debug on or off */
};


Index: 2.6-git/kernel/sysctl.c
===================================================================
--- 2.6-git.orig/kernel/sysctl.c
+++ 2.6-git/kernel/sysctl.c
@@ -131,6 +131,10 @@ extern int acct_parm[];
extern int no_unaligned_warning;
#endif

+#ifdef CONFIG_DEBUG_KREF
+extern int kref_debug;
+#endif
+
static int parse_table(int __user *, int, void __user *, size_t __user *, void __user *, size_t,
ctl_table *, void **);
static int proc_doutsstring(ctl_table *table, int write, struct file *filp,
@@ -683,6 +687,16 @@ static ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
#endif
+#ifdef CONFIG_DEBUG_KREF
+ {
+ .ctl_name = KERN_KREF_DEBUG,
+ .procname = "kref_debug",
+ .data = &kref_debug,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+#endif
{ .ctl_name = 0 }
};

Index: 2.6-git/Documentation/sysctl/kernel.txt
===================================================================
--- 2.6-git.orig/Documentation/sysctl/kernel.txt
+++ 2.6-git/Documentation/sysctl/kernel.txt
@@ -27,6 +27,7 @@ show up in /proc/sys/kernel:
- hotplug
- java-appletviewer [ binfmt_java, obsolete ]
- java-interpreter [ binfmt_java, obsolete ]
+- kref_debug
- l2cr [ PPC only ]
- modprobe ==> Documentation/kmod.txt
- msgmax
@@ -161,6 +162,13 @@ Default value is "/sbin/hotplug".

==============================================================

+kref_debug:
+
+This flag controls the kref debugging. If 0, kref debugging is
+disabled. Enabled if nonzero.
+
+==============================================================
+
l2cr: (PPC only)

This flag controls the L2 cache of G3 processor boards. If

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