Messages in this thread | | | Date | Fri, 05 Feb 2010 14:33:20 +0800 | From | Cong Wang <> | Subject | Re: [Patch] sysfs: add lockdep class support to s_active |
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Amerigo Wang wrote: > 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/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]); >
Oops! I missed one part, please ignore this patch...
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