* [PATCH] block: prevent sending events from removed device
@ 2021-06-30 8:09 Christian Löhle
2021-06-30 11:46 ` [PATCHv2] " Christian Löhle
2021-07-01 7:42 ` [PATCH] " Christoph Hellwig
0 siblings, 2 replies; 4+ messages in thread
From: Christian Löhle @ 2021-06-30 8:09 UTC (permalink / raw)
To: linux-kernel, linux-block, axboe, Christian Löhle
Skip kobject_uevent_env in case the associated kobject
no longer exists, as calling kobject_uevent_env with
NULL is not safe.
Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
---
block/genhd.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index 9f8cb7beaad1..46629fbe23ae 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1655,8 +1655,16 @@ static void disk_check_events(struct disk_events *ev,
(disk->event_flags & DISK_EVENT_FLAG_UEVENT))
envp[nr_events++] = disk_uevents[i];
- if (nr_events)
- kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+ if (nr_events) {
+ struct kobject *dev_kobj = kobject_get(&disk_to_dev(disk)->kobj);
+ /* The device kobject might have been removed in the
+ * meantime, so check for it first.
+ * If it was removed there is no need to signal events
+ */
+ if (!dev_kobj)
+ kobject_uevent_env(dev_kobj, KOBJ_CHANGE, envp);
+ kobject_put(dev_kobj);
+ }
}
/*
--
2.32.0
Hyperstone GmbH | Line-Eid-Strasse 3 | 78467 Konstanz
Managing Directors: Dr. Jan Peter Berns.
Commercial register of local courts: Freiburg HRB381782
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCHv2] block: prevent sending events from removed device
2021-06-30 8:09 [PATCH] block: prevent sending events from removed device Christian Löhle
@ 2021-06-30 11:46 ` Christian Löhle
2021-07-01 7:42 ` [PATCH] " Christoph Hellwig
1 sibling, 0 replies; 4+ messages in thread
From: Christian Löhle @ 2021-06-30 11:46 UTC (permalink / raw)
To: linux-kernel, linux-block, axboe, Christian Löhle
Skip kobject_uevent_env in case the associated kobject
no longer exists, as calling kobject_uevent_env with
NULL is not safe.
Signed-off-by: Christian Loehle <cloehle@hyperstone.com>
---
block/genhd.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index 9f8cb7beaad1..46629fbe23ae 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1655,8 +1655,16 @@ static void disk_check_events(struct disk_events *ev,
(disk->event_flags & DISK_EVENT_FLAG_UEVENT))
envp[nr_events++] = disk_uevents[i];
- if (nr_events)
- kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+ if (nr_events) {
+ struct kobject *dev_kobj = kobject_get(&disk_to_dev(disk)->kobj);
+ /* The device kobject might have been removed in the
+ * meantime, so check for it first.
+ * If it was removed there is no need to signal events
+ */
+ if (dev_kobj)
+ kobject_uevent_env(dev_kobj, KOBJ_CHANGE, envp);
+ kobject_put(dev_kobj);
+ }
}
/*
--
2.32.0
Hyperstone GmbH | Line-Eid-Strasse 3 | 78467 Konstanz
Managing Directors: Dr. Jan Peter Berns.
Commercial register of local courts: Freiburg HRB381782
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] block: prevent sending events from removed device
2021-06-30 8:09 [PATCH] block: prevent sending events from removed device Christian Löhle
2021-06-30 11:46 ` [PATCHv2] " Christian Löhle
@ 2021-07-01 7:42 ` Christoph Hellwig
2021-07-01 8:23 ` Christian Löhle
1 sibling, 1 reply; 4+ messages in thread
From: Christoph Hellwig @ 2021-07-01 7:42 UTC (permalink / raw)
To: Christian L?hle; +Cc: linux-kernel, linux-block, axboe
On Wed, Jun 30, 2021 at 08:09:39AM +0000, Christian L?hle wrote:
> Skip kobject_uevent_env in case the associated kobject
> no longer exists, as calling kobject_uevent_env with
> NULL is not safe.
>
I don't see how this is going to work. If the device is being
deleted the reference count will be zero and refcount_inc as
called from kobject_get will WARN. We'll need to check the
disk is marked up, and we need to do that under a lock.
Something like this completely untested patch:
diff --git a/block/disk-events.c b/block/disk-events.c
index a75931ff5da4..27b845c51f2a 100644
--- a/block/disk-events.c
+++ b/block/disk-events.c
@@ -190,6 +190,9 @@ static void disk_check_events(struct disk_events *ev,
spin_unlock_irq(&ev->lock);
+ if (!(disk->flags & GENHD_FL_UP))
+ return;
+
/*
* Tell userland about new events. Only the events listed in
* @disk->events are reported, and only if DISK_EVENT_FLAG_UEVENT
@@ -268,6 +271,8 @@ bool bdev_check_media_change(struct block_device *bdev)
{
unsigned int events;
+ lockdep_assert_held(&bdev->bd_disk->open_mutex);
+
events = disk_clear_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE |
DISK_EVENT_EJECT_REQUEST);
if (!(events & DISK_EVENT_MEDIA_CHANGE))
@@ -290,7 +295,10 @@ static void disk_events_workfn(struct work_struct *work)
struct delayed_work *dwork = to_delayed_work(work);
struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
- disk_check_events(ev, &ev->clearing);
+ mutex_lock(&ev->disk->open_mutex);
+ if (ev->disk->flags & GENHD_FL_UP)
+ disk_check_events(ev, &ev->clearing);
+ mutex_unlock(&ev->disk->open_mutex);
}
/*
diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c
index a093644ac39f..b8e77da44235 100644
--- a/drivers/block/ataflop.c
+++ b/drivers/block/ataflop.c
@@ -1735,8 +1735,10 @@ static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode,
/* invalidate the buffer track to force a reread */
BufferDrive = -1;
set_bit(drive, &fake_change);
+ mutex_lock(&bdev->bd_disk->open_mutex);
if (bdev_check_media_change(bdev))
floppy_revalidate(bdev->bd_disk);
+ mutex_unlock(&bdev->bd_disk->open_mutex);
return 0;
default:
return -EINVAL;
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 87460e0e5c72..2a97f22cfa0b 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3185,8 +3185,10 @@ static int invalidate_drive(struct block_device *bdev)
/* invalidate the buffer track to force a reread */
set_bit((long)bdev->bd_disk->private_data, &fake_change);
process_fd_request();
+ mutex_lock(&bdev->bd_disk->open_mutex);
if (bdev_check_media_change(bdev))
floppy_revalidate(bdev->bd_disk);
+ mutex_unlock(&bdev->bd_disk->open_mutex);
return 0;
}
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] block: prevent sending events from removed device
2021-07-01 7:42 ` [PATCH] " Christoph Hellwig
@ 2021-07-01 8:23 ` Christian Löhle
0 siblings, 0 replies; 4+ messages in thread
From: Christian Löhle @ 2021-07-01 8:23 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: linux-kernel, linux-block, axboe
Alright Thanks, I will try out your suggestion and report back.
Regards,
Christian
>I don't see how this is going to work. If the device is being
>deleted the reference count will be zero and refcount_inc as
>called from kobject_get will WARN. We'll need to check the
>disk is marked up, and we need to do that under a lock.
>
>Something like this completely untested patch:
diff --git a/block/disk-events.c b/block/disk-events.c
index a75931ff5da4..27b845c51f2a 100644
--- a/block/disk-events.c
+++ b/block/disk-events.c
@@ -190,6 +190,9 @@ static void disk_check_events(struct disk_events *ev,
spin_unlock_irq(&ev->lock);
+ if (!(disk->flags & GENHD_FL_UP))
+ return;
+
/*
* Tell userland about new events. Only the events listed in
* @disk->events are reported, and only if DISK_EVENT_FLAG_UEVENT
@@ -268,6 +271,8 @@ bool bdev_check_media_change(struct block_device *bdev)
{
unsigned int events;
+ lockdep_assert_held(&bdev->bd_disk->open_mutex);
+
events = disk_clear_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE |
DISK_EVENT_EJECT_REQUEST);
if (!(events & DISK_EVENT_MEDIA_CHANGE))
@@ -290,7 +295,10 @@ static void disk_events_workfn(struct work_struct *work)
struct delayed_work *dwork = to_delayed_work(work);
struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
- disk_check_events(ev, &ev->clearing);
+ mutex_lock(&ev->disk->open_mutex);
+ if (ev->disk->flags & GENHD_FL_UP)
+ disk_check_events(ev, &ev->clearing);
+ mutex_unlock(&ev->disk->open_mutex);
}
/*
diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c
index a093644ac39f..b8e77da44235 100644
--- a/drivers/block/ataflop.c
+++ b/drivers/block/ataflop.c
@@ -1735,8 +1735,10 @@ static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode,
/* invalidate the buffer track to force a reread */
BufferDrive = -1;
set_bit(drive, &fake_change);
+ mutex_lock(&bdev->bd_disk->open_mutex);
if (bdev_check_media_change(bdev))
floppy_revalidate(bdev->bd_disk);
+ mutex_unlock(&bdev->bd_disk->open_mutex);
return 0;
default:
return -EINVAL;
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 87460e0e5c72..2a97f22cfa0b 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3185,8 +3185,10 @@ static int invalidate_drive(struct block_device *bdev)
/* invalidate the buffer track to force a reread */
set_bit((long)bdev->bd_disk->private_data, &fake_change);
process_fd_request();
+ mutex_lock(&bdev->bd_disk->open_mutex);
if (bdev_check_media_change(bdev))
floppy_revalidate(bdev->bd_disk);
+ mutex_unlock(&bdev->bd_disk->open_mutex);
return 0;
}
Hyperstone GmbH | Line-Eid-Strasse 3 | 78467 Konstanz
Managing Directors: Dr. Jan Peter Berns.
Commercial register of local courts: Freiburg HRB381782
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-07-01 8:23 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-06-30 8:09 [PATCH] block: prevent sending events from removed device Christian Löhle
2021-06-30 11:46 ` [PATCHv2] " Christian Löhle
2021-07-01 7:42 ` [PATCH] " Christoph Hellwig
2021-07-01 8:23 ` Christian Löhle
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