From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756555Ab3JNN1S (ORCPT ); Mon, 14 Oct 2013 09:27:18 -0400 Received: from mail-qa0-f43.google.com ([209.85.216.43]:36250 "EHLO mail-qa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755955Ab3JNN1Q (ORCPT ); Mon, 14 Oct 2013 09:27:16 -0400 Date: Mon, 14 Oct 2013 09:27:11 -0400 From: Tejun Heo To: Greg KH Cc: Yinghai Lu , Kay Sievers , Linux Kernel Mailing List , "Eric W. Biederman" , Bjorn Helgaas Subject: [PATCH driver-core-next] sysfs: make sysfs_file_ops() follow ignore_lockdep flag Message-ID: <20131014132711.GC4722@htj.dyndns.org> References: <1380663729-18243-1-git-send-email-tj@kernel.org> <20131006004032.GA3601@kroah.com> <20131007170005.GB2481@htj.dyndns.org> <20131007231136.GB27270@kroah.com> <20131011204904.GA1308@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131011204904.GA1308@kroah.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 375b611e60 ("sysfs: remove sysfs_buffer->ops") introduced sysfs_file_ops() which determines the associated file operation of a given sysfs_dirent. As file ops access should be protected by an active reference, the new function includes a lockdep assertion on the sysfs_dirent; unfortunately, I forgot to take attr->ignore_lockdep flag into account and the lockdep assertion trips spuriously for files which opt out from active reference lockdep checking. # cat /sys/devices/pci0000:00/0000:00:01.2/usb1/authorized ------------[ cut here ]------------ WARNING: CPU: 1 PID: 540 at /work/os/work/fs/sysfs/file.c:79 sysfs_file_ops+0x4e/0x60() Modules linked in: CPU: 1 PID: 540 Comm: cat Not tainted 3.11.0-work+ #3 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 0000000000000009 ffff880016205c08 ffffffff81ca0131 0000000000000000 ffff880016205c40 ffffffff81096d0d ffff8800166cb898 ffff8800166f6f60 ffffffff8125a220 ffff880011ab1ec0 ffff88000aff0c78 ffff880016205c50 Call Trace: [] dump_stack+0x4e/0x82 [] warn_slowpath_common+0x7d/0xa0 [] warn_slowpath_null+0x1a/0x20 [] sysfs_file_ops+0x4e/0x60 [] sysfs_open_file+0x54/0x300 [] do_dentry_open.isra.17+0x182/0x280 [] finish_open+0x30/0x40 [] do_last+0x503/0xd90 [] path_openat+0xbb/0x6d0 [] do_filp_open+0x3a/0x90 [] do_sys_open+0x129/0x220 [] SyS_open+0x1e/0x20 [] system_call_fastpath+0x16/0x1b ---[ end trace aa48096b111dafdb ]--- Rename fs/sysfs/dir.c::ignore_lockdep() to sysfs_ignore_lockdep() and move it to fs/sysfs/sysfs.h and make sysfs_file_ops() skip lockdep assertion if sysfs_ignore_lockdep() is true. Signed-off-by: Tejun Heo Reported-by: Yinghai Lu --- fs/sysfs/dir.c | 22 ++-------------------- fs/sysfs/file.c | 3 ++- fs/sysfs/sysfs.h | 16 ++++++++++++++++ 3 files changed, 20 insertions(+), 21 deletions(-) --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -144,24 +144,6 @@ static void sysfs_unlink_sibling(struct sd->s_parent->s_flags &= ~SYSFS_FLAG_HAS_NS; } -#ifdef CONFIG_DEBUG_LOCK_ALLOC - -/* Test for attributes that want to ignore lockdep for read-locking */ -static bool ignore_lockdep(struct sysfs_dirent *sd) -{ - return sysfs_type(sd) == SYSFS_KOBJ_ATTR && - sd->s_attr.attr->ignore_lockdep; -} - -#else - -static inline bool ignore_lockdep(struct sysfs_dirent *sd) -{ - return true; -} - -#endif - /** * sysfs_get_active - get an active reference to sysfs_dirent * @sd: sysfs_dirent to get an active reference to @@ -180,7 +162,7 @@ struct sysfs_dirent *sysfs_get_active(st if (!atomic_inc_unless_negative(&sd->s_active)) return NULL; - if (likely(!ignore_lockdep(sd))) + if (likely(!sysfs_ignore_lockdep(sd))) rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_); return sd; } @@ -199,7 +181,7 @@ void sysfs_put_active(struct sysfs_diren if (unlikely(!sd)) return; - if (likely(!ignore_lockdep(sd))) + if (likely(!sysfs_ignore_lockdep(sd))) rwsem_release(&sd->dep_map, 1, _RET_IP_); v = atomic_dec_return(&sd->s_active); if (likely(v != SD_DEACTIVATED_BIAS)) --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -76,7 +76,8 @@ static const struct sysfs_ops *sysfs_fil { struct kobject *kobj = sd->s_parent->s_dir.kobj; - lockdep_assert_held(sd); + if (!sysfs_ignore_lockdep(sd)) + lockdep_assert_held(sd); return kobj->ktype ? kobj->ktype->sysfs_ops : NULL; } --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -103,6 +103,7 @@ static inline unsigned int sysfs_type(st } #ifdef CONFIG_DEBUG_LOCK_ALLOC + #define sysfs_dirent_init_lockdep(sd) \ do { \ struct attribute *attr = sd->s_attr.attr; \ @@ -112,8 +113,23 @@ do { \ \ lockdep_init_map(&sd->dep_map, "s_active", key, 0); \ } while (0) + +/* Test for attributes that want to ignore lockdep for read-locking */ +static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd) +{ + return sysfs_type(sd) == SYSFS_KOBJ_ATTR && + sd->s_attr.attr->ignore_lockdep; +} + #else + #define sysfs_dirent_init_lockdep(sd) do {} while (0) + +static inline bool sysfs_ignore_lockdep(struct sysfs_dirent *sd) +{ + return true; +} + #endif /*