On 11/06/2011 08:48 PM, Rakib Mullick wrote: > 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@xxxxxxxxx> > Cc: Lin Ming <ming.m.lin@xxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Len Brown <len.brown@xxxxxxxxx> > Cc: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> > --- > It would be a good idea to also give the lockdep warning in the changelog (though you triggered it in a modified kernel), since that would make it very clear as to what problem your patch is trying to solve. [And please line-wrap your changelog to 80 characters at most, per line]. Code-wise, the patch looks good to me. So, Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> Thanks, Srivatsa S. Bhat > diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c > index 55accb7..cc70f3f 100644 > --- a/drivers/acpi/acpica/hwregs.c > +++ b/drivers/acpi/acpica/hwregs.c > @@ -269,16 +269,17 @@ acpi_status acpi_hw_clear_acpi_status(void) > > status = acpi_hw_register_write(ACPI_REGISTER_PM1_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 */ > > 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); > +exit: > return_ACPI_STATUS(status); > } > > > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
