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SubjectRe: [PATCH -v1] acpi: Fix possible recursive locking in hwregs.c
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On Thu, 2011-11-03 at 18:48 +0800, Rakib Mullick wrote:
> Calling pm-suspend might trigger a recursive lock in it's code path. In function acpi_hw_clear_acpi_status,

As I replied at https://lkml.org/lkml/2011/9/22/6, I still don't think
there is a recursive lock.

Or do you have a real test case to trigger the recursive lock you
mentioned?

Lin Ming

> 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(https://lkml.org/lkml/2011/9/21/355):
> - Fix changelog, thanks to Lin Ming.
>
> Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
> Cc: Lin Ming <ming.m.lin@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Len Brown <len.brown@intel.com>
> ---
>
> 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_BITMASK_ALL_FIXED_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);
>
> unlock_and_exit:
> - acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
> return_ACPI_STATUS(status);
> }
>
>
>




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