* [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection()
[not found] <20180730184052.13442-1-bart.vanassche@wdc.com>
@ 2018-07-30 18:40 ` Bart Van Assche
2018-08-01 15:53 ` Tejun Heo
2018-08-02 8:31 ` Greg Kroah-Hartman
2018-07-30 18:40 ` [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock Bart Van Assche
1 sibling, 2 replies; 9+ messages in thread
From: Bart Van Assche @ 2018-07-30 18:40 UTC (permalink / raw)
To: Martin K . Petersen, James E . J . Bottomley
Cc: linux-scsi, Greg Kroah-Hartman, Tejun Heo, Bart Van Assche, stable
Introduce these two functions and export them such that the next patch
can add calls to these functions from the SCSI core.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
---
fs/sysfs/file.c | 44 +++++++++++++++++++++++++++++++++++++++++++
include/linux/sysfs.h | 14 ++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 5c13f29bfcdb..118fa197a35f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -405,6 +405,50 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
}
EXPORT_SYMBOL_GPL(sysfs_chmod_file);
+/**
+ * sysfs_break_active_protection - break "active" protection
+ * @kobj: The kernel object @attr is associated with.
+ * @attr: The attribute to break the "active" protection for.
+ *
+ * With sysfs, just like kernfs, deletion of an attribute is postponed until
+ * all active .show() and .store() callbacks have finished unless this function
+ * is called. Hence this function is useful in methods that implement self
+ * deletion.
+ */
+struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
+ const struct attribute *attr)
+{
+ struct kernfs_node *kn;
+
+ kobject_get(kobj);
+ kn = kernfs_find_and_get(kobj->sd, attr->name);
+ if (kn)
+ kernfs_break_active_protection(kn);
+ return kn;
+}
+EXPORT_SYMBOL_GPL(sysfs_break_active_protection);
+
+/**
+ * sysfs_unbreak_active_protection - restore "active" protection
+ * @kn: Pointer returned by sysfs_break_active_protection().
+ *
+ * Undo the effects of sysfs_break_active_protection(). Since this function
+ * calls kernfs_put() on the kernfs node that corresponds to the 'attr'
+ * argument passed to sysfs_break_active_protection() that attribute may have
+ * been removed between the sysfs_break_active_protection() and
+ * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after
+ * this function has returned.
+ */
+void sysfs_unbreak_active_protection(struct kernfs_node *kn)
+{
+ struct kobject *kobj = kn->parent->priv;
+
+ kernfs_unbreak_active_protection(kn);
+ kernfs_put(kn);
+ kobject_put(kobj);
+}
+EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection);
+
/**
* sysfs_remove_file_ns - remove an object attribute with a custom ns tag
* @kobj: object we're acting for
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index b8bfdc173ec0..3c12198c0103 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -237,6 +237,9 @@ int __must_check sysfs_create_files(struct kobject *kobj,
const struct attribute **attr);
int __must_check sysfs_chmod_file(struct kobject *kobj,
const struct attribute *attr, umode_t mode);
+struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
+ const struct attribute *attr);
+void sysfs_unbreak_active_protection(struct kernfs_node *kn);
void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
const void *ns);
bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr);
@@ -350,6 +353,17 @@ static inline int sysfs_chmod_file(struct kobject *kobj,
return 0;
}
+static inline struct kernfs_node *
+sysfs_break_active_protection(struct kobject *kobj,
+ const struct attribute *attr)
+{
+ return NULL;
+}
+
+static inline void sysfs_unbreak_active_protection(struct kernfs_node *kn)
+{
+}
+
static inline void sysfs_remove_file_ns(struct kobject *kobj,
const struct attribute *attr,
const void *ns)
--
2.18.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock
[not found] <20180730184052.13442-1-bart.vanassche@wdc.com>
2018-07-30 18:40 ` [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection() Bart Van Assche
@ 2018-07-30 18:40 ` Bart Van Assche
2018-08-01 15:54 ` Tejun Heo
2018-08-01 21:16 ` Bart Van Assche
1 sibling, 2 replies; 9+ messages in thread
From: Bart Van Assche @ 2018-07-30 18:40 UTC (permalink / raw)
To: Martin K . Petersen, James E . J . Bottomley
Cc: linux-scsi, Greg Kroah-Hartman, Tejun Heo, Bart Van Assche,
Johannes Thumshirn, stable
A long time ago the unfortunate decision was taken to add a self-
deletion attribute to the sysfs SCSI device directory. That decision
was unfortunate because self-deletion is really tricky. We can't drop
that attribute because widely used user space software depends on it,
namely the rescan-scsi-bus.sh script. Hence this patch that avoids
that writing into that attribute triggers a deadlock. See also commit
7973cbd9fbd9 ("[PATCH] add sysfs attributes to scan and delete
scsi_devices").
This patch avoids that self-removal triggers the following deadlock:
======================================================
WARNING: possible circular locking dependency detected
4.18.0-rc2-dbg+ #5 Not tainted
------------------------------------------------------
modprobe/6539 is trying to acquire lock:
000000008323c4cd (kn->count#202){++++}, at: kernfs_remove_by_name_ns+0x45/0x90
but task is already holding lock:
00000000a6ec2c69 (&shost->scan_mutex){+.+.}, at: scsi_remove_host+0x21/0x150 [scsi_mod]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&shost->scan_mutex){+.+.}:
__mutex_lock+0xfe/0xc70
mutex_lock_nested+0x1b/0x20
scsi_remove_device+0x26/0x40 [scsi_mod]
sdev_store_delete+0x27/0x30 [scsi_mod]
dev_attr_store+0x3e/0x50
sysfs_kf_write+0x87/0xa0
kernfs_fop_write+0x190/0x230
__vfs_write+0xd2/0x3b0
vfs_write+0x101/0x270
ksys_write+0xab/0x120
__x64_sys_write+0x43/0x50
do_syscall_64+0x77/0x230
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (kn->count#202){++++}:
lock_acquire+0xd2/0x260
__kernfs_remove+0x424/0x4a0
kernfs_remove_by_name_ns+0x45/0x90
remove_files.isra.1+0x3a/0x90
sysfs_remove_group+0x5c/0xc0
sysfs_remove_groups+0x39/0x60
device_remove_attrs+0x82/0xb0
device_del+0x251/0x580
__scsi_remove_device+0x19f/0x1d0 [scsi_mod]
scsi_forget_host+0x37/0xb0 [scsi_mod]
scsi_remove_host+0x9b/0x150 [scsi_mod]
sdebug_driver_remove+0x4b/0x150 [scsi_debug]
device_release_driver_internal+0x241/0x360
device_release_driver+0x12/0x20
bus_remove_device+0x1bc/0x290
device_del+0x259/0x580
device_unregister+0x1a/0x70
sdebug_remove_adapter+0x8b/0xf0 [scsi_debug]
scsi_debug_exit+0x76/0xe8 [scsi_debug]
__x64_sys_delete_module+0x1c1/0x280
do_syscall_64+0x77/0x230
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&shost->scan_mutex);
lock(kn->count#202);
lock(&shost->scan_mutex);
lock(kn->count#202);
*** DEADLOCK ***
2 locks held by modprobe/6539:
#0: 00000000efaf9298 (&dev->mutex){....}, at: device_release_driver_internal+0x68/0x360
#1: 00000000a6ec2c69 (&shost->scan_mutex){+.+.}, at: scsi_remove_host+0x21/0x150 [scsi_mod]
stack backtrace:
CPU: 10 PID: 6539 Comm: modprobe Not tainted 4.18.0-rc2-dbg+ #5
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
Call Trace:
dump_stack+0xa4/0xf5
print_circular_bug.isra.34+0x213/0x221
__lock_acquire+0x1a7e/0x1b50
lock_acquire+0xd2/0x260
__kernfs_remove+0x424/0x4a0
kernfs_remove_by_name_ns+0x45/0x90
remove_files.isra.1+0x3a/0x90
sysfs_remove_group+0x5c/0xc0
sysfs_remove_groups+0x39/0x60
device_remove_attrs+0x82/0xb0
device_del+0x251/0x580
__scsi_remove_device+0x19f/0x1d0 [scsi_mod]
scsi_forget_host+0x37/0xb0 [scsi_mod]
scsi_remove_host+0x9b/0x150 [scsi_mod]
sdebug_driver_remove+0x4b/0x150 [scsi_debug]
device_release_driver_internal+0x241/0x360
device_release_driver+0x12/0x20
bus_remove_device+0x1bc/0x290
device_del+0x259/0x580
device_unregister+0x1a/0x70
sdebug_remove_adapter+0x8b/0xf0 [scsi_debug]
scsi_debug_exit+0x76/0xe8 [scsi_debug]
__x64_sys_delete_module+0x1c1/0x280
do_syscall_64+0x77/0x230
entry_SYSCALL_64_after_hwframe+0x49/0xbe
See also https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg54525.html.
Fixes: ac0ece9174ac ("scsi: use device_remove_file_self() instead of device_schedule_callback()")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
---
drivers/scsi/scsi_sysfs.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index de122354d09a..3aee9464a7bf 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -722,8 +722,24 @@ static ssize_t
sdev_store_delete(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
- if (device_remove_file_self(dev, attr))
- scsi_remove_device(to_scsi_device(dev));
+ struct kernfs_node *kn;
+
+ kn = sysfs_break_active_protection(&dev->kobj, &attr->attr);
+ WARN_ON_ONCE(!kn);
+ /*
+ * Concurrent writes into the "delete" sysfs attribute may trigger
+ * concurrent calls to device_remove_file() and scsi_remove_device().
+ * device_remove_file() handles concurrent removal calls by
+ * serializing these and by ignoring the second and later removal
+ * attempts. Concurrent calls of scsi_remove_device() are
+ * serialized. The second and later calls of scsi_remove_device() are
+ * ignored because the first call of that function changes the device
+ * state into SDEV_DEL.
+ */
+ device_remove_file(dev, attr);
+ scsi_remove_device(to_scsi_device(dev));
+ if (kn)
+ sysfs_unbreak_active_protection(kn);
return count;
};
static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
--
2.18.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection()
2018-07-30 18:40 ` [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection() Bart Van Assche
@ 2018-08-01 15:53 ` Tejun Heo
2018-08-02 8:31 ` Greg Kroah-Hartman
1 sibling, 0 replies; 9+ messages in thread
From: Tejun Heo @ 2018-08-01 15:53 UTC (permalink / raw)
To: Bart Van Assche
Cc: Martin K . Petersen, James E . J . Bottomley, linux-scsi,
Greg Kroah-Hartman, stable
On Mon, Jul 30, 2018 at 11:40:51AM -0700, Bart Van Assche wrote:
> Introduce these two functions and export them such that the next patch
> can add calls to these functions from the SCSI core.
>
> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: <stable@vger.kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock
2018-07-30 18:40 ` [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock Bart Van Assche
@ 2018-08-01 15:54 ` Tejun Heo
2018-08-01 21:16 ` Bart Van Assche
1 sibling, 0 replies; 9+ messages in thread
From: Tejun Heo @ 2018-08-01 15:54 UTC (permalink / raw)
To: Bart Van Assche
Cc: Martin K . Petersen, James E . J . Bottomley, linux-scsi,
Greg Kroah-Hartman, Johannes Thumshirn, stable
On Mon, Jul 30, 2018 at 11:40:52AM -0700, Bart Van Assche wrote:
> A long time ago the unfortunate decision was taken to add a self-
> deletion attribute to the sysfs SCSI device directory. That decision
> was unfortunate because self-deletion is really tricky. We can't drop
> that attribute because widely used user space software depends on it,
> namely the rescan-scsi-bus.sh script. Hence this patch that avoids
> that writing into that attribute triggers a deadlock. See also commit
> 7973cbd9fbd9 ("[PATCH] add sysfs attributes to scan and delete
> scsi_devices").
Acked-by: Tejun Heo <tj@kernel.org>
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock
2018-07-30 18:40 ` [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock Bart Van Assche
2018-08-01 15:54 ` Tejun Heo
@ 2018-08-01 21:16 ` Bart Van Assche
2018-08-01 22:58 ` Bart Van Assche
1 sibling, 1 reply; 9+ messages in thread
From: Bart Van Assche @ 2018-08-01 21:16 UTC (permalink / raw)
To: jejb, martin.petersen; +Cc: linux-scsi, tj, jthumshirn, gregkh, stable
On Mon, 2018-07-30 at 11:40 -0700, Bart Van Assche wrote:
> A long time ago the unfortunate decision was taken to add a self-
> deletion attribute to the sysfs SCSI device directory. That decision
> was unfortunate because self-deletion is really tricky. We can't drop
> that attribute because widely used user space software depends on it,
> namely the rescan-scsi-bus.sh script. Hence this patch that avoids
> that writing into that attribute triggers a deadlock. See also commit
> 7973cbd9fbd9 ("[PATCH] add sysfs attributes to scan and delete
> scsi_devices").
[ ... ]
During my kernel tests of today I noticed that this patch makes booting
significantly slower: boot time for a VM increases from 6s to 157s. Martin,
please drop this patch series.
Thanks,
Bart.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock
2018-08-01 21:16 ` Bart Van Assche
@ 2018-08-01 22:58 ` Bart Van Assche
2018-08-02 17:47 ` Bart Van Assche
0 siblings, 1 reply; 9+ messages in thread
From: Bart Van Assche @ 2018-08-01 22:58 UTC (permalink / raw)
To: jejb, martin.petersen; +Cc: linux-scsi, tj, jthumshirn, gregkh, stable
On Wed, 2018-08-01 at 21:16 +0000, Bart Van Assche wrote:
> During my kernel tests of today I noticed that this patch makes booting
> significantly slower: boot time for a VM increases from 6s to 157s. Martin,
> please drop this patch series.
Please ignore my previous message - these two patches are fine. The trouble
was caused by a patch in another tree that I had merged in during my tests.
I will repost this series.
Bart.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection()
2018-07-30 18:40 ` [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection() Bart Van Assche
2018-08-01 15:53 ` Tejun Heo
@ 2018-08-02 8:31 ` Greg Kroah-Hartman
1 sibling, 0 replies; 9+ messages in thread
From: Greg Kroah-Hartman @ 2018-08-02 8:31 UTC (permalink / raw)
To: Bart Van Assche
Cc: Martin K . Petersen, James E . J . Bottomley, linux-scsi,
Tejun Heo, stable
On Mon, Jul 30, 2018 at 11:40:51AM -0700, Bart Van Assche wrote:
> Introduce these two functions and export them such that the next patch
> can add calls to these functions from the SCSI core.
>
> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: <stable@vger.kernel.org>
> ---
> fs/sysfs/file.c | 44 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/sysfs.h | 14 ++++++++++++++
> 2 files changed, 58 insertions(+)
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock
2018-08-01 22:58 ` Bart Van Assche
@ 2018-08-02 17:47 ` Bart Van Assche
0 siblings, 0 replies; 9+ messages in thread
From: Bart Van Assche @ 2018-08-02 17:47 UTC (permalink / raw)
To: jejb, martin.petersen; +Cc: linux-scsi, tj, jthumshirn, gregkh, stable
On Wed, 2018-08-01 at 22:58 +0000, Bart Van Assche wrote:
> On Wed, 2018-08-01 at 21:16 +0000, Bart Van Assche wrote:
> > During my kernel tests of today I noticed that this patch makes booting
> > significantly slower: boot time for a VM increases from 6s to 157s. Martin,
> > please drop this patch series.
>
> Please ignore my previous message - these two patches are fine. The trouble
> was caused by a patch in another tree that I had merged in during my tests.
> I will repost this series.
The following patch fixes the boot time regression I had reported yesterday:
https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg74940.html.
Bart.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection()
[not found] <20180802175141.8699-1-bart.vanassche@wdc.com>
@ 2018-08-02 17:51 ` Bart Van Assche
0 siblings, 0 replies; 9+ messages in thread
From: Bart Van Assche @ 2018-08-02 17:51 UTC (permalink / raw)
To: Martin K . Petersen, James E . J . Bottomley
Cc: linux-scsi, Greg Kroah-Hartman, Tejun Heo, Bart Van Assche, stable
Introduce these two functions and export them such that the next patch
can add calls to these functions from the SCSI core.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
---
fs/sysfs/file.c | 44 +++++++++++++++++++++++++++++++++++++++++++
include/linux/sysfs.h | 14 ++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 5c13f29bfcdb..118fa197a35f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -405,6 +405,50 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
}
EXPORT_SYMBOL_GPL(sysfs_chmod_file);
+/**
+ * sysfs_break_active_protection - break "active" protection
+ * @kobj: The kernel object @attr is associated with.
+ * @attr: The attribute to break the "active" protection for.
+ *
+ * With sysfs, just like kernfs, deletion of an attribute is postponed until
+ * all active .show() and .store() callbacks have finished unless this function
+ * is called. Hence this function is useful in methods that implement self
+ * deletion.
+ */
+struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
+ const struct attribute *attr)
+{
+ struct kernfs_node *kn;
+
+ kobject_get(kobj);
+ kn = kernfs_find_and_get(kobj->sd, attr->name);
+ if (kn)
+ kernfs_break_active_protection(kn);
+ return kn;
+}
+EXPORT_SYMBOL_GPL(sysfs_break_active_protection);
+
+/**
+ * sysfs_unbreak_active_protection - restore "active" protection
+ * @kn: Pointer returned by sysfs_break_active_protection().
+ *
+ * Undo the effects of sysfs_break_active_protection(). Since this function
+ * calls kernfs_put() on the kernfs node that corresponds to the 'attr'
+ * argument passed to sysfs_break_active_protection() that attribute may have
+ * been removed between the sysfs_break_active_protection() and
+ * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after
+ * this function has returned.
+ */
+void sysfs_unbreak_active_protection(struct kernfs_node *kn)
+{
+ struct kobject *kobj = kn->parent->priv;
+
+ kernfs_unbreak_active_protection(kn);
+ kernfs_put(kn);
+ kobject_put(kobj);
+}
+EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection);
+
/**
* sysfs_remove_file_ns - remove an object attribute with a custom ns tag
* @kobj: object we're acting for
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index b8bfdc173ec0..3c12198c0103 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -237,6 +237,9 @@ int __must_check sysfs_create_files(struct kobject *kobj,
const struct attribute **attr);
int __must_check sysfs_chmod_file(struct kobject *kobj,
const struct attribute *attr, umode_t mode);
+struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
+ const struct attribute *attr);
+void sysfs_unbreak_active_protection(struct kernfs_node *kn);
void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
const void *ns);
bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr);
@@ -350,6 +353,17 @@ static inline int sysfs_chmod_file(struct kobject *kobj,
return 0;
}
+static inline struct kernfs_node *
+sysfs_break_active_protection(struct kobject *kobj,
+ const struct attribute *attr)
+{
+ return NULL;
+}
+
+static inline void sysfs_unbreak_active_protection(struct kernfs_node *kn)
+{
+}
+
static inline void sysfs_remove_file_ns(struct kobject *kobj,
const struct attribute *attr,
const void *ns)
--
2.18.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
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2018-07-30 18:40 ` [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection() Bart Van Assche
2018-08-01 15:53 ` Tejun Heo
2018-08-02 8:31 ` Greg Kroah-Hartman
2018-07-30 18:40 ` [PATCH 2/2] Avoid that SCSI device removal through sysfs triggers a deadlock Bart Van Assche
2018-08-01 15:54 ` Tejun Heo
2018-08-01 21:16 ` Bart Van Assche
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2018-08-02 17:51 ` [PATCH 1/2] sysfs: Introduce sysfs_{un,}break_active_protection() Bart Van Assche
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