Messages in this thread Patch in this message | | | Date | Fri, 5 Feb 2010 01:42:56 -0500 | From | Amerigo Wang <> | Subject | [Patch v2] sysfs: add lockdep class support to s_active |
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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@kernel.crashing.org> Reported-by: Larry Finger <Larry.Finger@lwfinger.net> Reported-by: Miles Lane <miles.lane@gmail.com> Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: WANG Cong <amwang@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Greg Kroah-Hartman <gregkh@suse.de>
--- diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 699f371..d7de269 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -354,7 +354,6 @@ struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type) atomic_set(&sd->s_count, 1); atomic_set(&sd->s_active, 0); - sysfs_dirent_init_lockdep(sd); sd->s_name = name; sd->s_mode = mode; diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index dc30d9e..97e397a 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_and_name(sd, &sysfs_classes[class], "s_active"); sysfs_addrm_start(&acxt, dir_sd); rc = sysfs_add_one(&acxt, sd); diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index cdd9377..dde4d73 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -88,17 +88,6 @@ static inline unsigned int sysfs_type(struct sysfs_dirent *sd) return sd->s_flags & SYSFS_TYPE_MASK; } -#ifdef CONFIG_DEBUG_LOCK_ALLOC -#define sysfs_dirent_init_lockdep(sd) \ -do { \ - static struct lock_class_key __key; \ - \ - lockdep_init_map(&sd->dep_map, "s_active", &__key, 0); \ -} while(0) -#else -#define sysfs_dirent_init_lockdep(sd) do {} while(0) -#endif - /* * Context structure to be used while adding/removing nodes. */ 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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