[PATCH 0/6] Fix deadlock in ftl formating on mtd

[Zhihao Cheng <chengzhihao1@huawei.com>]

There is an AA-deadlock problem while formating mtd device to generate
a ftl device. Fix it by reverting "mtd: allow to unload the mtdtrans
module if its block devices aren't open" recommended in [1].

[<0>] blktrans_open+0x47/0x340            LOCK(mtd_table_mutex)
[<0>] __blkdev_get+0x5b/0x3e0
[<0>] blkdev_get_by_dev+0x18f/0x370
[<0>] __device_add_disk+0x2db/0x700
[<0>] device_add_disk+0x17/0x20
[<0>] add_mtd_blktrans_dev+0x39e/0x6d0
[<0>] ftl_add_mtd+0x792/0x908 [ftl]
[<0>] register_mtd_blktrans+0xfb/0x170    LOCK(mtd_table_mutex)
[<0>] ftl_tr_init+0x18/0x1000 [ftl]
[<0>] do_one_initcall+0x71/0x330
[<0>] do_init_module+0xa6/0x350

[1] http://lists.infradead.org/pipermail/linux-mtd/2017-March/072899.html

Zhihao Cheng (6):
  Revert "mtd: blkdevs: fix potential deadlock + lockdep warnings"
  Revert "mtd: fix: avoid race condition when accessing mtd->usecount"
  Revert "mtd: mtd_blkdevs: don't increase 'open' count on error path"
  Revert "mtd: mtd_blkdevs: fix error path in blktrans_open"
  Revert "mtd: Remove redundant mutex from mtd_blkdevs.c"
  Revert "mtd: allow to unload the mtdtrans module if its block devices
    aren't open"

 drivers/mtd/mtd_blkdevs.c | 77 +++++++++++++++------------------------
 1 file changed, 30 insertions(+), 47 deletions(-)

-- 
2.31.1