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Message-Id: <20100205062814.4119.53209.sendpatchset@localhost.localdomain>
Date: Fri, 5 Feb 2010 01:24:48 -0500
From: Amerigo Wang <amwang@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>, Greg Kroah-Hartman <gregkh@...e.de>,
Peter Zijlstra <peterz@...radead.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Miles Lane <miles.lane@...il.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Larry Finger <Larry.Finger@...inger.net>,
Amerigo Wang <amwang@...hat.com>, akpm@...ux-foundation.org
Subject: [Patch] sysfs: add lockdep class support to s_active
Recently we met a lockdep warning from sysfs during s2ram or cpu hotplug.
As reported by several people, it is something like:
[ 6967.926563] ACPI: Preparing to enter system sleep state S3
[ 6967.956156] Disabling non-boot CPUs ...
[ 6967.970401]
[ 6967.970408] =============================================
[ 6967.970419] [ INFO: possible recursive locking detected ]
[ 6967.970431] 2.6.33-rc2-git6 #27
[ 6967.970439] ---------------------------------------------
[ 6967.970450] pm-suspend/22147 is trying to acquire lock:
[ 6967.970460] (s_active){++++.+}, at: [<c10d2941>]
sysfs_hash_and_remove+0x3d/0x4f
[ 6967.970493]
[ 6967.970497] but task is already holding lock:
[ 6967.970506] (s_active){++++.+}, at: [<c10d4110>]
sysfs_get_active_two+0x16/0x36
[...]
Eric already provides a patch for this[1], but it still can't fix the
problem. Based on his work and Peter's suggestion, I write this patch,
hopefully we can fix the warning completely.
This patch put sysfs s_active into two classes, one is for PM, the other
is for the rest, so lockdep will distinguish them.
1. http://lkml.org/lkml/2010/1/10/282
Reported-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Reported-by: Larry Finger <Larry.Finger@...inger.net>
Reported-by: Miles Lane <miles.lane@...il.com>
Reported-by: Heiko Carstens <heiko.carstens@...ibm.com>
Signed-off-by: WANG Cong <amwang@...hat.com>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Tejun Heo <tj@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...e.de>
---
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index dc30d9e..72a8d0b 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -24,6 +24,8 @@
#include "sysfs.h"
+static struct lock_class_key sysfs_classes[SYSFS_NR_CLASSES];
+
/* used in crash dumps to help with debugging */
static char last_sysfs_file[PATH_MAX];
void sysfs_printk_last_file(void)
@@ -504,11 +506,16 @@ int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;
int rc;
+ int class;
sd = sysfs_new_dirent(attr->name, mode, type);
if (!sd)
return -ENOMEM;
sd->s_attr.attr = (void *)attr;
+ class = SYSFS_ATTR_NORMAL;
+ if (sysfs_type(sd) == SYSFS_KOBJ_ATTR)
+ class = sd->s_attr.attr->class;
+ lockdep_set_class(&sd->s_active, &sysfs_classes[class]);
sysfs_addrm_start(&acxt, dir_sd);
rc = sysfs_add_one(&acxt, sd);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index cfa8308..2b91b74 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -20,6 +20,12 @@
struct kobject;
struct module;
+enum sysfs_attr_lock_class {
+ SYSFS_ATTR_NORMAL,
+ SYSFS_ATTR_PM_CONTROL,
+ SYSFS_NR_CLASSES,
+};
+
/* FIXME
* The *owner field is no longer used.
* x86 tree has been cleaned up. The owner
@@ -29,6 +35,7 @@ struct attribute {
const char *name;
struct module *owner;
mode_t mode;
+ enum sysfs_attr_lock_class class;
};
struct attribute_group {
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 46c5a26..67a6fe7 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -54,13 +54,14 @@ extern int hibernation_platform_enter(void);
extern int pfn_is_nosave(unsigned long);
#define power_attr(_name) \
-static struct kobj_attribute _name##_attr = { \
- .attr = { \
- .name = __stringify(_name), \
- .mode = 0644, \
- }, \
- .show = _name##_show, \
- .store = _name##_store, \
+static struct kobj_attribute _name##_attr = { \
+ .attr = { \
+ .name = __stringify(_name), \
+ .mode = 0644, \
+ .class = SYSFS_ATTR_PM_CONTROL, \
+ }, \
+ .show = _name##_show, \
+ .store = _name##_store, \
}
/* Preferred image size in bytes (default 500 MB) */
--
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