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Message-ID: <20131014132711.GC4722@htj.dyndns.org>
Date: Mon, 14 Oct 2013 09:27:11 -0400
From: Tejun Heo <tj@...nel.org>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: Yinghai Lu <yinghai@...nel.org>, Kay Sievers <kay@...y.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH driver-core-next] sysfs: make sysfs_file_ops() follow
ignore_lockdep flag
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:
[<ffffffff81ca0131>] dump_stack+0x4e/0x82
[<ffffffff81096d0d>] warn_slowpath_common+0x7d/0xa0
[<ffffffff81096dea>] warn_slowpath_null+0x1a/0x20
[<ffffffff8125994e>] sysfs_file_ops+0x4e/0x60
[<ffffffff8125a274>] sysfs_open_file+0x54/0x300
[<ffffffff811df612>] do_dentry_open.isra.17+0x182/0x280
[<ffffffff811df820>] finish_open+0x30/0x40
[<ffffffff811f0623>] do_last+0x503/0xd90
[<ffffffff811f0f6b>] path_openat+0xbb/0x6d0
[<ffffffff811f23ba>] do_filp_open+0x3a/0x90
[<ffffffff811e09a9>] do_sys_open+0x129/0x220
[<ffffffff811e0abe>] SyS_open+0x1e/0x20
[<ffffffff81caf3c2>] 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 <tj@...nel.org>
Reported-by: Yinghai Lu <yinghai@...nel.org>
---
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
/*
--
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