Commit f7f71cfb authored Nov 06, 2011 by Rakib Mullick Committed by Len Brown Nov 06, 2011

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.
Both acpi_gbl_hardware_lock and acpi_gbl_gpe_lock are at same
lock-class and which might cause lock recursion deadlock.

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.

 Changes since v1 (https://lkml.org/lkml/2011/11/3/89

):
	- Update changelog and rename goto label, courtesy Srivatsa S. Bhat.

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

parent c3b92c87

drivers/acpi/acpica/hwregs.c

+6 −5

Original line number	Original line	Diff line number	Diff line
	@@ -269,16 +269,17 @@ acpi_status acpi_hw_clear_acpi_status(void)

	status = acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,		status = acpi_hw_register_write(ACPI_REGISTER_PM1_STATUS,
	ACPI_BITMASK_ALL_FIXED_STATUS);		ACPI_BITMASK_ALL_FIXED_STATUS);
	if (ACPI_FAILURE(status)) {
	goto unlock_and_exit;		acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
	}
			if (ACPI_FAILURE(status))
			goto exit;

	/* Clear the GPE Bits in all GPE registers in all GPE blocks */		/* Clear the GPE Bits in all GPE registers in all GPE blocks */

	status = acpi_ev_walk_gpe_list(acpi_hw_clear_gpe_block, NULL);		status = acpi_ev_walk_gpe_list(acpi_hw_clear_gpe_block, NULL);

	unlock_and_exit:		exit:
	acpi_os_release_lock(acpi_gbl_hardware_lock, lock_flags);
	return_ACPI_STATUS(status);		return_ACPI_STATUS(status);
	}		}