* [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
@ 2017-01-29 4:58 Dan Williams
2017-01-30 7:05 ` Hannes Reinecke
2017-01-30 12:24 ` Christoph Hellwig
0 siblings, 2 replies; 9+ messages in thread
From: Dan Williams @ 2017-01-29 4:58 UTC (permalink / raw)
To: martin.petersen
Cc: Jens Axboe, linux-block, linux-scsi, linux-kernel,
James Bottomley, Bart Van Assche, Omar Sandoval,
Christoph Hellwig
Warnings of the following form occur because scsi reuses a devt number
while the block layer still has it referenced as the name of the bdi
[1]:
WARNING: CPU: 1 PID: 93 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:192'
[..]
Call Trace:
dump_stack+0x86/0xc3
__warn+0xcb/0xf0
warn_slowpath_fmt+0x5f/0x80
? kernfs_path_from_node+0x4f/0x60
sysfs_warn_dup+0x62/0x80
sysfs_create_dir_ns+0x77/0x90
kobject_add_internal+0xb2/0x350
kobject_add+0x75/0xd0
device_add+0x15a/0x650
device_create_groups_vargs+0xe0/0xf0
device_create_vargs+0x1c/0x20
bdi_register+0x90/0x240
? lockdep_init_map+0x57/0x200
bdi_register_owner+0x36/0x60
device_add_disk+0x1bb/0x4e0
? __pm_runtime_use_autosuspend+0x5c/0x70
sd_probe_async+0x10d/0x1c0
async_run_entry_fn+0x39/0x170
This is a brute-force fix to pass the devt release information from
sd_probe() to the locations where we register the bdi,
device_add_disk(), and unregister the bdi, blk_cleanup_queue().
Thanks to Omar for the quick reproducer script [2]. This patch survives
where an unmodified kernel fails in a few seconds.
[1]: https://marc.info/?l=linux-scsi&m=147116857810716&w=4
[2]: http://marc.info/?l=linux-block&m=148554717109098&w=2
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Reported-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
block/blk-core.c | 1 +
block/genhd.c | 7 +++++++
drivers/scsi/sd.c | 41 +++++++++++++++++++++++++++++++++--------
include/linux/blkdev.h | 1 +
include/linux/genhd.h | 17 +++++++++++++++++
5 files changed, 59 insertions(+), 8 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 61ba08c58b64..950cea1e202e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -597,6 +597,7 @@ void blk_cleanup_queue(struct request_queue *q)
spin_unlock_irq(lock);
bdi_unregister(&q->backing_dev_info);
+ put_disk_devt(q->disk_devt);
/* @q is and will stay empty, shutdown and put */
blk_put_queue(q);
diff --git a/block/genhd.c b/block/genhd.c
index fcd6d4fae657..eb8009e928f5 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -612,6 +612,13 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
disk_alloc_events(disk);
+ /*
+ * Take a reference on the devt and assign it to queue since it
+ * must not be reallocated while the bdi is registerted
+ */
+ disk->queue->disk_devt = disk->disk_devt;
+ get_disk_devt(disk->disk_devt);
+
/* Register BDI before referencing it from bdev */
bdi = &disk->queue->backing_dev_info;
bdi_register_owner(bdi, disk_to_dev(disk));
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 0b09638fa39b..09405351577c 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3067,6 +3067,23 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
put_device(&sdkp->dev);
}
+struct sd_devt {
+ int idx;
+ struct disk_devt disk_devt;
+};
+
+void sd_devt_release(struct kref *kref)
+{
+ struct sd_devt *sd_devt = container_of(kref, struct sd_devt,
+ disk_devt.kref);
+
+ spin_lock(&sd_index_lock);
+ ida_remove(&sd_index_ida, sd_devt->idx);
+ spin_unlock(&sd_index_lock);
+
+ kfree(sd_devt);
+}
+
/**
* sd_probe - called during driver initialization and whenever a
* new scsi device is attached to the system. It is called once
@@ -3088,6 +3105,7 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
static int sd_probe(struct device *dev)
{
struct scsi_device *sdp = to_scsi_device(dev);
+ struct sd_devt *sd_devt;
struct scsi_disk *sdkp;
struct gendisk *gd;
int index;
@@ -3113,9 +3131,13 @@ static int sd_probe(struct device *dev)
if (!sdkp)
goto out;
+ sd_devt = kzalloc(sizeof(*sd_devt), GFP_KERNEL);
+ if (!sd_devt)
+ goto out_free;
+
gd = alloc_disk(SD_MINORS);
if (!gd)
- goto out_free;
+ goto out_free_devt;
do {
if (!ida_pre_get(&sd_index_ida, GFP_KERNEL))
@@ -3131,6 +3153,11 @@ static int sd_probe(struct device *dev)
goto out_put;
}
+ kref_init(&sd_devt->disk_devt.kref);
+ sd_devt->disk_devt.release = sd_devt_release;
+ sd_devt->idx = index;
+ gd->disk_devt = &sd_devt->disk_devt;
+
error = sd_format_disk_name("sd", index, gd->disk_name, DISK_NAME_LEN);
if (error) {
sdev_printk(KERN_WARNING, sdp, "SCSI disk (sd) name length exceeded.\n");
@@ -3170,13 +3197,14 @@ static int sd_probe(struct device *dev)
return 0;
out_free_index:
- spin_lock(&sd_index_lock);
- ida_remove(&sd_index_ida, index);
- spin_unlock(&sd_index_lock);
+ put_disk_devt(&sd_devt->disk_devt);
+ sd_devt = NULL;
out_put:
put_disk(gd);
out_free:
kfree(sdkp);
+ out_free_devt:
+ kfree(sd_devt);
out:
scsi_autopm_put_device(sdp);
return error;
@@ -3235,10 +3263,7 @@ static void scsi_disk_release(struct device *dev)
struct scsi_disk *sdkp = to_scsi_disk(dev);
struct gendisk *disk = sdkp->disk;
- spin_lock(&sd_index_lock);
- ida_remove(&sd_index_ida, sdkp->index);
- spin_unlock(&sd_index_lock);
-
+ put_disk_devt(disk->disk_devt);
disk->private_data = NULL;
put_disk(disk);
put_device(&sdkp->device->sdev_gendev);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1ca8e8fd1078..0432d1b44188 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -432,6 +432,7 @@ struct request_queue {
*/
struct delayed_work delay_work;
+ struct disk_devt *disk_devt;
struct backing_dev_info backing_dev_info;
/*
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 76f39754e7b0..5a5efe6a0de1 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -167,6 +167,22 @@ struct blk_integrity {
};
#endif /* CONFIG_BLK_DEV_INTEGRITY */
+struct disk_devt {
+ struct kref kref;
+ void (*release)(struct kref *);
+};
+
+static inline void put_disk_devt(struct disk_devt *disk_devt)
+{
+ if (disk_devt)
+ kref_put(&disk_devt->kref, disk_devt->release);
+}
+
+static inline void get_disk_devt(struct disk_devt *disk_devt)
+{
+ if (disk_devt)
+ kref_get(&disk_devt->kref);
+}
struct gendisk {
/* major, first_minor and minors are input parameters only,
@@ -176,6 +192,7 @@ struct gendisk {
int first_minor;
int minors; /* maximum number of minors, =1 for
* disks that can't be partitioned. */
+ struct disk_devt *disk_devt;
char disk_name[DISK_NAME_LEN]; /* name of major driver */
char *(*devnode)(struct gendisk *gd, umode_t *mode);
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-29 4:58 [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes Dan Williams
@ 2017-01-30 7:05 ` Hannes Reinecke
2017-01-30 7:22 ` Omar Sandoval
2017-01-30 12:24 ` Christoph Hellwig
1 sibling, 1 reply; 9+ messages in thread
From: Hannes Reinecke @ 2017-01-30 7:05 UTC (permalink / raw)
To: Dan Williams, martin.petersen
Cc: Jens Axboe, linux-block, linux-scsi, linux-kernel,
James Bottomley, Bart Van Assche, Omar Sandoval,
Christoph Hellwig
On 01/29/2017 05:58 AM, Dan Williams wrote:
> Warnings of the following form occur because scsi reuses a devt number
> while the block layer still has it referenced as the name of the bdi
> [1]:
>
> WARNING: CPU: 1 PID: 93 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
> sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:192'
> [..]
> Call Trace:
> dump_stack+0x86/0xc3
> __warn+0xcb/0xf0
> warn_slowpath_fmt+0x5f/0x80
> ? kernfs_path_from_node+0x4f/0x60
> sysfs_warn_dup+0x62/0x80
> sysfs_create_dir_ns+0x77/0x90
> kobject_add_internal+0xb2/0x350
> kobject_add+0x75/0xd0
> device_add+0x15a/0x650
> device_create_groups_vargs+0xe0/0xf0
> device_create_vargs+0x1c/0x20
> bdi_register+0x90/0x240
> ? lockdep_init_map+0x57/0x200
> bdi_register_owner+0x36/0x60
> device_add_disk+0x1bb/0x4e0
> ? __pm_runtime_use_autosuspend+0x5c/0x70
> sd_probe_async+0x10d/0x1c0
> async_run_entry_fn+0x39/0x170
>
> This is a brute-force fix to pass the devt release information from
> sd_probe() to the locations where we register the bdi,
> device_add_disk(), and unregister the bdi, blk_cleanup_queue().
>
> Thanks to Omar for the quick reproducer script [2]. This patch survives
> where an unmodified kernel fails in a few seconds.
>
> [1]: https://marc.info/?l=linux-scsi&m=147116857810716&w=4
> [2]: http://marc.info/?l=linux-block&m=148554717109098&w=2
>
> Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
> Cc: Bart Van Assche <bart.vanassche@sandisk.com>
> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Jens Axboe <axboe@kernel.dk>
> Reported-by: Omar Sandoval <osandov@osandov.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> block/blk-core.c | 1 +
> block/genhd.c | 7 +++++++
> drivers/scsi/sd.c | 41 +++++++++++++++++++++++++++++++++--------
> include/linux/blkdev.h | 1 +
> include/linux/genhd.h | 17 +++++++++++++++++
> 5 files changed, 59 insertions(+), 8 deletions(-)
>
Please check the patchset from Jan Kara (cf 'BDI lifetime fix' on
linux-block), which attempts to solve the same problem.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-30 7:05 ` Hannes Reinecke
@ 2017-01-30 7:22 ` Omar Sandoval
2017-01-30 7:46 ` Dan Williams
0 siblings, 1 reply; 9+ messages in thread
From: Omar Sandoval @ 2017-01-30 7:22 UTC (permalink / raw)
To: Hannes Reinecke
Cc: Dan Williams, martin.petersen, Jens Axboe, linux-block,
linux-scsi, linux-kernel, James Bottomley, Bart Van Assche,
Christoph Hellwig
On Mon, Jan 30, 2017 at 08:05:52AM +0100, Hannes Reinecke wrote:
> On 01/29/2017 05:58 AM, Dan Williams wrote:
> > Warnings of the following form occur because scsi reuses a devt number
> > while the block layer still has it referenced as the name of the bdi
> > [1]:
> >
> > WARNING: CPU: 1 PID: 93 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
> > sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:192'
> > [..]
> > Call Trace:
> > dump_stack+0x86/0xc3
> > __warn+0xcb/0xf0
> > warn_slowpath_fmt+0x5f/0x80
> > ? kernfs_path_from_node+0x4f/0x60
> > sysfs_warn_dup+0x62/0x80
> > sysfs_create_dir_ns+0x77/0x90
> > kobject_add_internal+0xb2/0x350
> > kobject_add+0x75/0xd0
> > device_add+0x15a/0x650
> > device_create_groups_vargs+0xe0/0xf0
> > device_create_vargs+0x1c/0x20
> > bdi_register+0x90/0x240
> > ? lockdep_init_map+0x57/0x200
> > bdi_register_owner+0x36/0x60
> > device_add_disk+0x1bb/0x4e0
> > ? __pm_runtime_use_autosuspend+0x5c/0x70
> > sd_probe_async+0x10d/0x1c0
> > async_run_entry_fn+0x39/0x170
> >
> > This is a brute-force fix to pass the devt release information from
> > sd_probe() to the locations where we register the bdi,
> > device_add_disk(), and unregister the bdi, blk_cleanup_queue().
> >
> > Thanks to Omar for the quick reproducer script [2]. This patch survives
> > where an unmodified kernel fails in a few seconds.
> >
> > [1]: https://marc.info/?l=linux-scsi&m=147116857810716&w=4
> > [2]: http://marc.info/?l=linux-block&m=148554717109098&w=2
> >
> > Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
> > Cc: Bart Van Assche <bart.vanassche@sandisk.com>
> > Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Jens Axboe <axboe@kernel.dk>
> > Reported-by: Omar Sandoval <osandov@osandov.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > ---
> > block/blk-core.c | 1 +
> > block/genhd.c | 7 +++++++
> > drivers/scsi/sd.c | 41 +++++++++++++++++++++++++++++++++--------
> > include/linux/blkdev.h | 1 +
> > include/linux/genhd.h | 17 +++++++++++++++++
> > 5 files changed, 59 insertions(+), 8 deletions(-)
> >
> Please check the patchset from Jan Kara (cf 'BDI lifetime fix' on
> linux-block), which attempts to solve the same problem.
Hi, Hannes,
It's not the same problem. Jan's series fixes a bdi vs. inode lifetime
issue, this patch is for a bdi vs devt lifetime issue. Jan's series
doesn't fix the crashes caused by my reproducer script.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-30 7:22 ` Omar Sandoval
@ 2017-01-30 7:46 ` Dan Williams
0 siblings, 0 replies; 9+ messages in thread
From: Dan Williams @ 2017-01-30 7:46 UTC (permalink / raw)
To: Omar Sandoval
Cc: Hannes Reinecke, Martin K. Petersen, Jens Axboe, linux-block,
linux-scsi, Linux Kernel Mailing List, James Bottomley,
Bart Van Assche, Christoph Hellwig
On Sun, Jan 29, 2017 at 11:22 PM, Omar Sandoval <osandov@osandov.com> wrote:
> On Mon, Jan 30, 2017 at 08:05:52AM +0100, Hannes Reinecke wrote:
>> On 01/29/2017 05:58 AM, Dan Williams wrote:
>> > Warnings of the following form occur because scsi reuses a devt number
>> > while the block layer still has it referenced as the name of the bdi
>> > [1]:
>> >
>> > WARNING: CPU: 1 PID: 93 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
>> > sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:192'
>> > [..]
>> > Call Trace:
>> > dump_stack+0x86/0xc3
>> > __warn+0xcb/0xf0
>> > warn_slowpath_fmt+0x5f/0x80
>> > ? kernfs_path_from_node+0x4f/0x60
>> > sysfs_warn_dup+0x62/0x80
>> > sysfs_create_dir_ns+0x77/0x90
>> > kobject_add_internal+0xb2/0x350
>> > kobject_add+0x75/0xd0
>> > device_add+0x15a/0x650
>> > device_create_groups_vargs+0xe0/0xf0
>> > device_create_vargs+0x1c/0x20
>> > bdi_register+0x90/0x240
>> > ? lockdep_init_map+0x57/0x200
>> > bdi_register_owner+0x36/0x60
>> > device_add_disk+0x1bb/0x4e0
>> > ? __pm_runtime_use_autosuspend+0x5c/0x70
>> > sd_probe_async+0x10d/0x1c0
>> > async_run_entry_fn+0x39/0x170
>> >
>> > This is a brute-force fix to pass the devt release information from
>> > sd_probe() to the locations where we register the bdi,
>> > device_add_disk(), and unregister the bdi, blk_cleanup_queue().
>> >
>> > Thanks to Omar for the quick reproducer script [2]. This patch survives
>> > where an unmodified kernel fails in a few seconds.
>> >
>> > [1]: https://marc.info/?l=linux-scsi&m=147116857810716&w=4
>> > [2]: http://marc.info/?l=linux-block&m=148554717109098&w=2
>> >
>> > Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
>> > Cc: Bart Van Assche <bart.vanassche@sandisk.com>
>> > Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
>> > Cc: Christoph Hellwig <hch@lst.de>
>> > Cc: Jens Axboe <axboe@kernel.dk>
>> > Reported-by: Omar Sandoval <osandov@osandov.com>
>> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>> > ---
>> > block/blk-core.c | 1 +
>> > block/genhd.c | 7 +++++++
>> > drivers/scsi/sd.c | 41 +++++++++++++++++++++++++++++++++--------
>> > include/linux/blkdev.h | 1 +
>> > include/linux/genhd.h | 17 +++++++++++++++++
>> > 5 files changed, 59 insertions(+), 8 deletions(-)
>> >
>> Please check the patchset from Jan Kara (cf 'BDI lifetime fix' on
>> linux-block), which attempts to solve the same problem.
>
> Hi, Hannes,
>
> It's not the same problem. Jan's series fixes a bdi vs. inode lifetime
> issue, this patch is for a bdi vs devt lifetime issue. Jan's series
> doesn't fix the crashes caused by my reproducer script.
Correct. In fact I was running Jan's patches in my baseline kernel
that fails almost immediately.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-29 4:58 [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes Dan Williams
2017-01-30 7:05 ` Hannes Reinecke
@ 2017-01-30 12:24 ` Christoph Hellwig
2017-01-30 20:57 ` Dan Williams
2017-01-30 21:53 ` Dan Williams
1 sibling, 2 replies; 9+ messages in thread
From: Christoph Hellwig @ 2017-01-30 12:24 UTC (permalink / raw)
To: Dan Williams
Cc: martin.petersen, Jens Axboe, linux-block, linux-scsi,
linux-kernel, James Bottomley, Bart Van Assche, Omar Sandoval,
Christoph Hellwig
Hi Dan,
this looks mostly fine to me. A few code comments below, but except
for this there is another issue with it: We still have drivers
that share a single request_queue for multiple gendisks, so I wonder
Also I think you probably want one patch for the block framework,
and one to switch SCSI over to it.
> +struct disk_devt {
> + struct kref kref;
> + void (*release)(struct kref *);
> +};
> +
> +static inline void put_disk_devt(struct disk_devt *disk_devt)
> +{
> + if (disk_devt)
> + kref_put(&disk_devt->kref, disk_devt->release);
> +}
> +
> +static inline void get_disk_devt(struct disk_devt *disk_devt)
> +{
> + if (disk_devt)
> + kref_get(&disk_devt->kref);
> +}
Given that we have a user-supplied release callack I'd much rather get
rid of the kref here, use a normal atomic_t and pass the disk_devt
structure to the release callback then a kref.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-30 12:24 ` Christoph Hellwig
@ 2017-01-30 20:57 ` Dan Williams
2017-02-01 8:08 ` Christoph Hellwig
2017-01-30 21:53 ` Dan Williams
1 sibling, 1 reply; 9+ messages in thread
From: Dan Williams @ 2017-01-30 20:57 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Jens Axboe, linux-block, linux-scsi,
linux-kernel, James Bottomley, Bart Van Assche, Omar Sandoval
On Mon, Jan 30, 2017 at 4:24 AM, Christoph Hellwig <hch@lst.de> wrote:
> Hi Dan,
>
> this looks mostly fine to me. A few code comments below, but except
> for this there is another issue with it: We still have drivers
> that share a single request_queue for multiple gendisks, so I wonder
>
> Also I think you probably want one patch for the block framework,
> and one to switch SCSI over to it.
>
>> +struct disk_devt {
>> + struct kref kref;
>> + void (*release)(struct kref *);
>> +};
>> +
>> +static inline void put_disk_devt(struct disk_devt *disk_devt)
>> +{
>> + if (disk_devt)
>> + kref_put(&disk_devt->kref, disk_devt->release);
>> +}
>> +
>> +static inline void get_disk_devt(struct disk_devt *disk_devt)
>> +{
>> + if (disk_devt)
>> + kref_get(&disk_devt->kref);
>> +}
>
> Given that we have a user-supplied release callack I'd much rather get
> rid of the kref here, use a normal atomic_t and pass the disk_devt
> structure to the release callback then a kref.
I'm missing something... kref is just:
struct kref {
atomic_t refcount;
};
...so what do we gain by open coding kref_get() and kref_put()?
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-30 12:24 ` Christoph Hellwig
2017-01-30 20:57 ` Dan Williams
@ 2017-01-30 21:53 ` Dan Williams
2017-02-01 8:07 ` Christoph Hellwig
1 sibling, 1 reply; 9+ messages in thread
From: Dan Williams @ 2017-01-30 21:53 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, Jens Axboe, linux-block, linux-scsi,
linux-kernel, James Bottomley, Bart Van Assche, Omar Sandoval
On Mon, Jan 30, 2017 at 4:24 AM, Christoph Hellwig <hch@lst.de> wrote:
> Hi Dan,
>
> this looks mostly fine to me. A few code comments below, but except
> for this there is another issue with it: We still have drivers
> that share a single request_queue for multiple gendisks, so I wonder
scsi drivers or others? If those drivers can switch to dynamically
allocated devt (GENHD_FL_EXT_DEVT), then they don't need this fix.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-30 21:53 ` Dan Williams
@ 2017-02-01 8:07 ` Christoph Hellwig
0 siblings, 0 replies; 9+ messages in thread
From: Christoph Hellwig @ 2017-02-01 8:07 UTC (permalink / raw)
To: Dan Williams
Cc: Christoph Hellwig, Martin K. Petersen, Jens Axboe, linux-block,
linux-scsi, linux-kernel, James Bottomley, Bart Van Assche,
Omar Sandoval
On Mon, Jan 30, 2017 at 01:53:36PM -0800, Dan Williams wrote:
> On Mon, Jan 30, 2017 at 4:24 AM, Christoph Hellwig <hch@lst.de> wrote:
> > Hi Dan,
> >
> > this looks mostly fine to me. A few code comments below, but except
> > for this there is another issue with it: We still have drivers
> > that share a single request_queue for multiple gendisks, so I wonder
>
> scsi drivers or others? If those drivers can switch to dynamically
> allocated devt (GENHD_FL_EXT_DEVT), then they don't need this fix.
Mostly old floppy drivers.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes
2017-01-30 20:57 ` Dan Williams
@ 2017-02-01 8:08 ` Christoph Hellwig
0 siblings, 0 replies; 9+ messages in thread
From: Christoph Hellwig @ 2017-02-01 8:08 UTC (permalink / raw)
To: Dan Williams
Cc: Christoph Hellwig, Martin K. Petersen, Jens Axboe, linux-block,
linux-scsi, linux-kernel, James Bottomley, Bart Van Assche,
Omar Sandoval
On Mon, Jan 30, 2017 at 12:57:05PM -0800, Dan Williams wrote:
>
> struct kref {
> atomic_t refcount;
> };
>
> ...so what do we gain by open coding kref_get() and kref_put()?
A much less ugly calling convention.
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2017-02-01 8:08 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-29 4:58 [RFC PATCH] scsi, block: fix duplicate bdi name registration crashes Dan Williams
2017-01-30 7:05 ` Hannes Reinecke
2017-01-30 7:22 ` Omar Sandoval
2017-01-30 7:46 ` Dan Williams
2017-01-30 12:24 ` Christoph Hellwig
2017-01-30 20:57 ` Dan Williams
2017-02-01 8:08 ` Christoph Hellwig
2017-01-30 21:53 ` Dan Williams
2017-02-01 8:07 ` Christoph Hellwig
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