target/linux/generic/hack-6.1/402-mtd-blktrans-call-add-disks-after-mtd-device.patch

   1 From 0bccc3722bdd88e8ae995e77ef9f7b77ee4cbdee Mon Sep 17 00:00:00 2001
   2 From: Daniel Golle <daniel@makrotopia.org>
   3 Date: Wed, 7 Apr 2021 22:45:54 +0100
   4 Subject: [PATCH 2/2] mtd: blktrans: call add disks after mtd device
   5 To: linux-mtd@lists.infradead.org
   6 Cc: Vignesh Raghavendra <vigneshr@ti.com>,
   7     Richard Weinberger <richard@nod.at>,
   8     Miquel Raynal <miquel.raynal@bootlin.com>,
   9     David Woodhouse <dwmw2@infradead.org>
  10
  11 Calling device_add_disk while holding mtd_table_mutex leads
  12 to deadlock in case part_bits!=0 as block partition parsers
  13 will try to open the newly created disks, trying to acquire
  14 mutex once again.
  15 Move device_add_disk to additional function called after
  16 add partitions of an MTD device have been added and locks
  17 have been released.
  18
  19 Signed-off-by: Daniel Golle <daniel@makrotopia.org>
  20 ---
  21  drivers/mtd/mtd_blkdevs.c    | 33 ++++++++++++++++++++++++++-------
  22  drivers/mtd/mtdcore.c        |  3 +++
  23  include/linux/mtd/blktrans.h |  1 +
  24  3 files changed, 30 insertions(+), 7 deletions(-)
  25
  26 --- a/drivers/mtd/mtd_blkdevs.c
  27 +++ b/drivers/mtd/mtd_blkdevs.c
  28 @@ -386,19 +386,8 @@ int add_mtd_blktrans_dev(struct mtd_blkt
  29         if (new->readonly)
  30                 set_disk_ro(gd, 1);
  31
  32 -       ret = device_add_disk(&new->mtd->dev, gd, NULL);
  33 -       if (ret)
  34 -               goto out_cleanup_disk;
  35 -
  36 -       if (new->disk_attributes) {
  37 -               ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
  38 -                                       new->disk_attributes);
  39 -               WARN_ON(ret);
  40 -       }
  41         return 0;
  42
  43 -out_cleanup_disk:
  44 -       put_disk(new->disk);
  45  out_free_tag_set:
  46         blk_mq_free_tag_set(new->tag_set);
  47  out_kfree_tag_set:
  48 @@ -408,6 +397,35 @@ out_list_del:
  49         return ret;
  50  }
  51
  52 +void register_mtd_blktrans_devs(void)
  53 +{
  54 +       struct mtd_blktrans_ops *tr;
  55 +       struct mtd_blktrans_dev *dev, *next;
  56 +       int ret;
  57 +
  58 +       list_for_each_entry(tr, &blktrans_majors, list) {
  59 +               list_for_each_entry_safe(dev, next, &tr->devs, list) {
  60 +                       if (disk_live(dev->disk))
  61 +                               continue;
  62 +
  63 +                       ret = device_add_disk(&dev->mtd->dev, dev->disk, NULL);
  64 +                       if (ret)
  65 +                               goto out_cleanup_disk;
  66 +
  67 +                       if (dev->disk_attributes) {
  68 +                               ret = sysfs_create_group(&disk_to_dev(dev->disk)->kobj,
  69 +                                                       dev->disk_attributes);
  70 +                               WARN_ON(ret);
  71 +                       }
  72 +               }
  73 +       }
  74 +
  75 +       return;
  76 +
  77 +out_cleanup_disk:
  78 +       put_disk(dev->disk);
  79 +}
  80 +
  81  int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
  82  {
  83         unsigned long flags;
  84 --- a/drivers/mtd/mtdcore.c
  85 +++ b/drivers/mtd/mtdcore.c
  86 @@ -32,6 +32,7 @@
  87
  88  #include <linux/mtd/mtd.h>
  89  #include <linux/mtd/partitions.h>
  90 +#include <linux/mtd/blktrans.h>
  91
  92  #include "mtdcore.h"
  93
  94 @@ -1098,6 +1099,8 @@ int mtd_device_parse_register(struct mtd
  95                 register_reboot_notifier(&mtd->reboot_notifier);
  96         }
  97
  98 +       register_mtd_blktrans_devs();
  99 +
 100  out:
 101         if (ret) {
 102                 nvmem_unregister(mtd->otp_user_nvmem);
 103 --- a/include/linux/mtd/blktrans.h
 104 +++ b/include/linux/mtd/blktrans.h
 105 @@ -76,6 +76,7 @@ extern int deregister_mtd_blktrans(struc
 106  extern int add_mtd_blktrans_dev(struct mtd_blktrans_dev *dev);
 107  extern int del_mtd_blktrans_dev(struct mtd_blktrans_dev *dev);
 108  extern int mtd_blktrans_cease_background(struct mtd_blktrans_dev *dev);
 109 +extern void register_mtd_blktrans_devs(void);
 110
 111  /**
 112   * module_mtd_blktrans() - Helper macro for registering a mtd blktrans driver