linux-stable.git/drivers/mtd/mtd_blkdevs.c, branch linux-5.14.y

mtd: fix lock hierarchy in deregister_mtd_blktrans

2021-08-06T19:44:16+00:00

There is a lock hierarchy of major_names_lock --> mtd_table_mutex. One
existing chain is as follows:

1. major_names_lock --> loop_ctl_mutex (when blk_request_module calls
loop_probe)

2. loop_ctl_mutex --> bdev->bd_mutex (when loop_control_ioctl calls
loop_remove, which then calls del_gendisk)

3. bdev->bd_mutex --> mtd_table_mutex (when blkdev_get_by_dev calls
__blkdev_get, which then calls blktrans_open)

Since unregister_blkdev grabs the major_names_lock, we need to call it
outside the critical section for mtd_table_mutex, otherwise we invert
the lock hierarchy.

Reported-by: Hillf Danton 
Signed-off-by: Desmond Cheong Zhi Xi 
Signed-off-by: Miquel Raynal 
Link: https://lore.kernel.org/linux-mtd/20210717100719.728829-1-desmondcheongzx@gmail.com

mtd: break circular locks in register_mtd_blktrans

2021-07-15T22:49:17+00:00

Syzbot reported a circular locking dependency:
https://syzkaller.appspot.com/bug?id=7bd106c28e846d1023d4ca915718b1a0905444cb

This happens because of the following lock dependencies:

1. loop_ctl_mutex -> bdev->bd_mutex (when loop_control_ioctl calls
loop_remove, which then calls del_gendisk; this also happens in
loop_exit which eventually calls loop_remove)

2. bdev->bd_mutex -> mtd_table_mutex (when blkdev_get_by_dev calls
__blkdev_get, which then calls blktrans_open)

3. mtd_table_mutex -> major_names_lock (when register_mtd_blktrans
calls __register_blkdev)

4. major_names_lock -> loop_ctl_mutex (when blk_request_module calls
loop_probe)

Hence there's an overall dependency of:

loop_ctl_mutex   ----------> bdev->bd_mutex
      ^                            |
      |                            |
      |                            v
major_names_lock <---------  mtd_table_mutex

We can break this circular dependency by holding mtd_table_mutex only
for the required critical section in register_mtd_blktrans. This
avoids the mtd_table_mutex -> major_names_lock dependency.

Reported-and-tested-by: syzbot+6a8a0d93c91e8fbf2e80@syzkaller.appspotmail.com
Co-developed-by: Christoph Hellwig 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Desmond Cheong Zhi Xi 
Signed-off-by: Miquel Raynal 
Link: https://lore.kernel.org/linux-mtd/20210617160904.570111-1-desmondcheongzx@gmail.com

mtd: mtd_blkdevs: Initialize rq.limits.discard_granularity

2021-07-15T22:49:13+00:00

Since commit b35fd7422c2f8("block: check queue's limits.discard_granularity
in __blkdev_issue_discard()") checks rq.limits.discard_granularity in
__blkdev_issue_discard(), we may get following warnings on formatted ftl:

  WARNING: CPU: 2 PID: 7313 at block/blk-lib.c:51
  __blkdev_issue_discard+0x2a7/0x390

Reproducer:
  1. ftl_format /dev/mtd0
  2. modprobe ftl
  3. mkfs.vfat /dev/ftla
  4. mount -odiscard /dev/ftla temp
  5. dd if=/dev/zero of=temp/tst bs=1M count=10 oflag=direct
  6. dd if=/dev/zero of=temp/tst bs=1M count=10 oflag=direct

Fix it by initializing rq.limits.discard_granularity if device supports
discard operation.

Signed-off-by: Zhihao Cheng 
Signed-off-by: Miquel Raynal 
Link: https://lore.kernel.org/linux-mtd/20210615093905.3473709-1-chengzhihao1@huawei.com

mtd_blkdevs: initialze new->rq in add_mtd_blktrans_dev

2021-06-16T12:53:50+00:00

Various places expect the request_queue in ->rq.  Initialize it to
avoid NULL pointer derefences.

Fixes: 6966bb921def ("mtd_blkdevs: use blk_mq_alloc_disk")
Reported-by: Marek Szyprowski 
Signed-off-by: Christoph Hellwig 
Tested-by: Marek Szyprowski 
Signed-off-by: Jens Axboe

mtd_blkdevs: use blk_mq_alloc_disk

2021-06-11T17:53:02+00:00

Use the blk_mq_alloc_disk API to simplify the gendisk and request_queue
allocation.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20210602065345.355274-10-hch@lst.de
Signed-off-by: Jens Axboe

mtd_blkdevs: don't override BLKFLSBUF

2020-11-16T15:14:29+00:00

BLKFLSBUF is not supposed to actually send a flush command to the device,
but to tear down buffer cache structures.  Remove the mtd_blkdevs
implementation and just use the default semantics instead.

Signed-off-by: Christoph Hellwig 
Acked-by: Richard Weinberger 
Signed-off-by: Jens Axboe

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 102

2019-05-24T15:39:00+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version this program is distributed in the
  hope that it will be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details you
  should have received a copy of the gnu general public license along
  with this program if not write to the free software foundation inc
  51 franklin st fifth floor boston ma 02110 1301 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 50 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Reviewed-by: Richard Fontana 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190523091649.499889647@linutronix.de
Signed-off-by: Greg Kroah-Hartman

mtd_blkdevs: convert to blk-mq

2018-10-16T14:09:58+00:00

Straight forward conversion, using an internal list to enable the
driver to pull requests at will.

Dynamically allocate the tag set to avoid having to pull in the
block headers for blktrans.h, since various mtd drivers use
block conflicting names for defines and functions.

Cc: David Woodhouse 
Cc: linux-mtd@lists.infradead.org
Tested-by: Richard Weinberger 
Signed-off-by: Jens Axboe

block: genhd: add 'groups' argument to device_add_disk

2018-09-28T14:30:28+00:00

Update device_add_disk() to take an 'groups' argument so that
individual drivers can register a device with additional sysfs
attributes.
This avoids race condition the driver would otherwise have if these
groups were to be created with sysfs_add_groups().

Signed-off-by: Martin Wilck 
Signed-off-by: Hannes Reinecke 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Bart Van Assche 
Signed-off-by: Jens Axboe

mtd_blkdevs: handle highmem pages

2018-05-11T21:07:58+00:00

Just kmap the single payload page before passing it on to the FTL.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe