| Message ID | 20210720182048.1906526-2-mcgrof@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: replace incorrect uses of GENHD_FL_UP | expand |
On Tue, Jul 20, 2021 at 11:20:44AM -0700, Luis Chamberlain wrote: > Often drivers may have complex setups where it is not > clear if their disk completed their respective *add_disk*() > call. They either have to invent a setting or, they > incorrectly use GENHD_FL_UP. Using GENHD_FL_UP however is > used internally so we know when we can add / remove > partitions safely. We can easily fail along the way > prior to add_disk() completing and still have > GENHD_FL_UP set, so it would not be correct in that case > to call del_gendisk() on the disk. > > Provide a new flag then which allows us to check if > *add_disk*() completed, and conversely just make > del_gendisk() check for this for drivers so that > they can safely call del_gendisk() and we'll figure > it out if it is safe for you to call this. > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > block/genhd.c | 8 ++++++++ > include/linux/genhd.h | 11 ++++++++++- > 2 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/block/genhd.c b/block/genhd.c > index af4d2ab4a633..a858eed05e55 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -539,6 +539,8 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk, > > disk_add_events(disk); > blk_integrity_add(disk); > + > + disk->flags |= GENHD_FL_DISK_ADDED; I guess I failed to mention it last time - but I think this needs to go into disk->state as dynamic state. > + * Drivers can safely call this even if they are not sure if the respective > + * __device_add_disk() call succeeded. > + * > * Drivers exist which depend on the release of the gendisk to be synchronous, > * it should not be deferred. > * > @@ -578,6 +583,9 @@ void del_gendisk(struct gendisk *disk) > { > might_sleep(); > > + if (!blk_disk_added(disk)) > + return; I still very much disagree with this check. It just leads to really bad driver code. In genral we need to _fix_ the existing abuses of the UP check in drivers, not spread this kind of sloppyness further.
diff --git a/block/genhd.c b/block/genhd.c index af4d2ab4a633..a858eed05e55 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -539,6 +539,8 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk, disk_add_events(disk); blk_integrity_add(disk); + + disk->flags |= GENHD_FL_DISK_ADDED; } void device_add_disk(struct device *parent, struct gendisk *disk, @@ -569,6 +571,9 @@ EXPORT_SYMBOL(device_add_disk_no_queue_reg); * with put_disk(), which should be called after del_gendisk(), if * __device_add_disk() was used. * + * Drivers can safely call this even if they are not sure if the respective + * __device_add_disk() call succeeded. + * * Drivers exist which depend on the release of the gendisk to be synchronous, * it should not be deferred. * @@ -578,6 +583,9 @@ void del_gendisk(struct gendisk *disk) { might_sleep(); + if (!blk_disk_added(disk)) + return; + if (WARN_ON_ONCE(!disk->queue)) return; diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 13b34177cc85..2470c8b56599 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -56,6 +56,10 @@ struct partition_meta_info { * Must not be set for devices which are removed entirely when the * media is removed. * + * ``GENHD_FL_DISK_ADDED`` (0x0002): used to clarify that the + * respective add_disk*() call completed successfully, so that + * we know we can safely process del_gendisk() on the disk. + * * ``GENHD_FL_CD`` (0x0008): the block device is a CD-ROM-style * device. * Affects responses to the ``CDROM_GET_CAPABILITY`` ioctl. @@ -94,7 +98,7 @@ struct partition_meta_info { * Used for multipath devices. */ #define GENHD_FL_REMOVABLE 0x0001 -/* 2 is unused (used to be GENHD_FL_DRIVERFS) */ +#define GENHD_FL_DISK_ADDED 0x0002 /* 4 is unused (used to be GENHD_FL_MEDIA_CHANGE_NOTIFY) */ #define GENHD_FL_CD 0x0008 #define GENHD_FL_UP 0x0010 @@ -189,6 +193,11 @@ struct gendisk { #define disk_to_cdi(disk) NULL #endif +static inline bool blk_disk_added(struct gendisk *disk) +{ + return disk && (disk->flags & GENHD_FL_DISK_ADDED); +} + static inline int disk_max_parts(struct gendisk *disk) { if (disk->flags & GENHD_FL_EXT_DEVT)
Often drivers may have complex setups where it is not clear if their disk completed their respective *add_disk*() call. They either have to invent a setting or, they incorrectly use GENHD_FL_UP. Using GENHD_FL_UP however is used internally so we know when we can add / remove partitions safely. We can easily fail along the way prior to add_disk() completing and still have GENHD_FL_UP set, so it would not be correct in that case to call del_gendisk() on the disk. Provide a new flag then which allows us to check if *add_disk*() completed, and conversely just make del_gendisk() check for this for drivers so that they can safely call del_gendisk() and we'll figure it out if it is safe for you to call this. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> --- block/genhd.c | 8 ++++++++ include/linux/genhd.h | 11 ++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-)