1. 26 Nov, 2014 38 commits
  2. 25 Nov, 2014 2 commits
    • Wolfram Sang's avatar
      i2c: at91: don't account as iowait · 0e16b1c3
      Wolfram Sang authored
      commit 11cfbfb0 upstream.
      
      iowait is for blkio [1]. I2C shouldn't use it.
      
      [1] https://lkml.org/lkml/2014/11/3/317Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
      Acked-by: default avatarLudovic Desroches <ludovic.desroches@atmel.com>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      0e16b1c3
    • Yijing Wang's avatar
      sysfs: driver core: Fix glue dir race condition by gdp_mutex · 88ae6682
      Yijing Wang authored
      commit e4a60d13 upstream.
      
      There is a race condition when removing glue directory.
      It can be reproduced in following test:
      
      path 1: Add first child device
      device_add()
          get_device_parent()
                  /*find parent from glue_dirs.list*/
                  list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
                          if (k->parent == parent_kobj) {
                                  kobj = kobject_get(k);
                                  break;
                          }
                  ....
                  class_dir_create_and_add()
      
      path2: Remove last child device under glue dir
      device_del()
          cleanup_device_parent()
                  cleanup_glue_dir()
                          kobject_put(glue_dir);
      
      If path2 has been called cleanup_glue_dir(), but not
      call kobject_put(glue_dir), the glue dir is still
      in parent's kset list. Meanwhile, path1 find the glue
      dir from the glue_dirs.list. Path2 may release glue dir
      before path1 call kobject_get(). So kernel will report
      the warning and bug_on.
      
      This is a "classic" problem we have of a kref in a list
      that can be found while the last instance could be removed
      at the same time.
      
      This patch reuse gdp_mutex to fix this race condition.
      
      The following calltrace is captured in kernel 3.4, but
      the latest kernel still has this bug.
      
      -----------------------------------------------------
      <4>[ 3965.441471] WARNING: at ...include/linux/kref.h:41 kobject_get+0x33/0x40()
      <4>[ 3965.441474] Hardware name: Romley
      <4>[ 3965.441475] Modules linked in: isd_iop(O) isd_xda(O)...
      ...
      <4>[ 3965.441605] Call Trace:
      <4>[ 3965.441611]  [<ffffffff8103717a>] warn_slowpath_common+0x7a/0xb0
      <4>[ 3965.441615]  [<ffffffff810371c5>] warn_slowpath_null+0x15/0x20
      <4>[ 3965.441618]  [<ffffffff81215963>] kobject_get+0x33/0x40
      <4>[ 3965.441624]  [<ffffffff812d1e45>] get_device_parent.isra.11+0x135/0x1f0
      <4>[ 3965.441627]  [<ffffffff812d22d4>] device_add+0xd4/0x6d0
      <4>[ 3965.441631]  [<ffffffff812d0dbc>] ? dev_set_name+0x3c/0x40
      ....
      <2>[ 3965.441912] kernel BUG at ..../fs/sysfs/group.c:65!
      <4>[ 3965.441915] invalid opcode: 0000 [#1] SMP
      ...
      <4>[ 3965.686743]  [<ffffffff811a677e>] sysfs_create_group+0xe/0x10
      <4>[ 3965.686748]  [<ffffffff810cfb04>] blk_trace_init_sysfs+0x14/0x20
      <4>[ 3965.686753]  [<ffffffff811fcabb>] blk_register_queue+0x3b/0x120
      <4>[ 3965.686756]  [<ffffffff812030bc>] add_disk+0x1cc/0x490
      ....
      -------------------------------------------------------
      Signed-off-by: default avatarYijing Wang <wangyijing@huawei.com>
      Signed-off-by: default avatarWeng Meiling <wengmeiling.weng@huawei.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      88ae6682