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    Subject[PATCH -v1] acpi: Fix possible recursive locking in hwregs.c
    Calling pm-suspend might trigger a recursive lock in it's code path. In function acpi_hw_clear_acpi_status, 
    acpi_os_acquire_lock holds the lock acpi_gbl_hardware_lock before calling acpi_hw_register_write(), then
    without releasing acpi_gbl_hardware_lock, this function calls acpi_ev_walk_gpe_list, which tries to hold
    acpi_gbl_gpe_lock and thus might causes possible recursive lock.

    Following patch fixes this scenario by just releasing acpi_gbl_hardware_lock before calling acpi_ev_walk_gpe_list.

    Changes since v0(
    - Fix changelog, thanks to Lin Ming.

    Signed-off-by: Rakib Mullick <>
    Cc: Lin Ming <>
    Cc: Andrew Morton <>
    Cc: Len Brown <>

    diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c
    index 55accb7..e3110ac 100644
    --- a/drivers/acpi/acpica/hwregs.c
    +++ b/drivers/acpi/acpica/hwregs.c
    @@ -269,6 +269,9 @@ acpi_status acpi_hw_clear_acpi_status(void)

    status = acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
    + acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
    if (ACPI_FAILURE(status)) {
    goto unlock_and_exit;
    @@ -278,7 +281,6 @@ acpi_status acpi_hw_clear_acpi_status(void)
    status = acpi_ev_walk_gpe_list(acpi_hw_clear_gpe_block, NULL);

    - acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);

     \ /
      Last update: 2011-11-03 11:51    [W:0.020 / U:19.356 seconds]
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