[GIT PATCH] additional ACPI patch for Linux-3.1-merge

[Len Brown]

Hi Linus,

please pull from: 

git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6.git release

Fixes a 3.1 regression.

thanks!

Len Brown
Intel Open Source Technology Center

ps. the patch is also available on linux-acpi@xxxxxxxxxxxxxxx

 drivers/acpi/battery.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

through these commits:

Sergey Senozhatsky (1):
      Battery: sysfs_remove_battery(): possible circular locking

with this log:

commit 69d94ec6d83d84044252d9ba03f6a8970816e350
Author: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Date:   Sat Aug 6 01:34:08 2011 +0300

    Battery: sysfs_remove_battery(): possible circular locking
    
    Commit 9c921c22a7f33397a6774d7fa076db9b6a0fd669
    Author: Lan Tianyu <tianyu.lan@xxxxxxxxx>
    
        ACPI / Battery: Resolve the race condition in the sysfs_remove_battery()
    
    fixed BUG https://bugzilla.kernel.org/show_bug.cgi?id=35642 , but as a side
    effect made lockdep unhappy with sysfs_remove_battery():
    
    [14818.477168]
    [14818.477170] =======================================================
    [14818.477200] [ INFO: possible circular locking dependency detected ]
    [14818.477221] 3.1.0-dbg-07865-g1280ea8-dirty #668
    [14818.477236] -------------------------------------------------------
    [14818.477257] s2ram/1599 is trying to acquire lock:
    [14818.477276]  (s_active#8){++++.+}, at: [<ffffffff81169147>] sysfs_addrm_finish+0x31/0x5a
    [14818.477323]
    [14818.477325] but task is already holding lock:
    [14818.477350]  (&battery->lock){+.+.+.}, at: [<ffffffffa0047278>] sysfs_remove_battery+0x10/0x4b [battery]
    [14818.477395]
    [14818.477397] which lock already depends on the new lock.
    [14818.477399]
    [..]
    [14818.479121] stack backtrace:
    [14818.479148] Pid: 1599, comm: s2ram Not tainted 3.1.0-dbg-07865-g1280ea8-dirty #668
    [14818.479175] Call Trace:
    [14818.479198]  [<ffffffff814828c3>] print_circular_bug+0x293/0x2a4
    [14818.479228]  [<ffffffff81070cb5>] __lock_acquire+0xfe4/0x164b
    [14818.479260]  [<ffffffff81169147>] ? sysfs_addrm_finish+0x31/0x5a
    [14818.479288]  [<ffffffff810718d2>] lock_acquire+0x138/0x1ac
    [14818.479316]  [<ffffffff81169147>] ? sysfs_addrm_finish+0x31/0x5a
    [14818.479345]  [<ffffffff81168a79>] sysfs_deactivate+0x9b/0xec
    [14818.479373]  [<ffffffff81169147>] ? sysfs_addrm_finish+0x31/0x5a
    [14818.479405]  [<ffffffff81169147>] sysfs_addrm_finish+0x31/0x5a
    [14818.479433]  [<ffffffff81167bc5>] sysfs_hash_and_remove+0x54/0x77
    [14818.479461]  [<ffffffff811681b9>] sysfs_remove_file+0x12/0x14
    [14818.479488]  [<ffffffff81385bf8>] device_remove_file+0x12/0x14
    [14818.479516]  [<ffffffff81386504>] device_del+0x119/0x17c
    [14818.479542]  [<ffffffff81386575>] device_unregister+0xe/0x1a
    [14818.479570]  [<ffffffff813c6ef9>] power_supply_unregister+0x23/0x27
    [14818.479601]  [<ffffffffa004729c>] sysfs_remove_battery+0x34/0x4b [battery]
    [14818.479632]  [<ffffffffa004778f>] battery_notify+0x2c/0x3a [battery]
    [14818.479662]  [<ffffffff8148fe82>] notifier_call_chain+0x74/0xa1
    [14818.479692]  [<ffffffff810624b4>] __blocking_notifier_call_chain+0x6c/0x89
    [14818.479722]  [<ffffffff810624e0>] blocking_notifier_call_chain+0xf/0x11
    [14818.479751]  [<ffffffff8107e40e>] pm_notifier_call_chain+0x15/0x27
    [14818.479770]  [<ffffffff8107ee1a>] enter_state+0xa7/0xd5
    [14818.479782]  [<ffffffff8107e341>] state_store+0xaa/0xc0
    [14818.479795]  [<ffffffff8107e297>] ? pm_async_store+0x45/0x45
    [14818.479807]  [<ffffffff81248837>] kobj_attr_store+0x17/0x19
    [14818.479820]  [<ffffffff81167e27>] sysfs_write_file+0x103/0x13f
    [14818.479834]  [<ffffffff81109037>] vfs_write+0xad/0x13d
    [14818.479847]  [<ffffffff811092b2>] sys_write+0x45/0x6c
    [14818.479860]  [<ffffffff81492f92>] system_call_fastpath+0x16/0x1b
    
    This patch introduces separate lock to struct acpi_battery to
    grab in sysfs_remove_battery() instead of battery->lock.
    So fix by Lan Tianyu is still there, we just grab independent lock.
    
    Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
    Tested-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
    Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
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