From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH -v2] acpi: Fix possible recursive locking in hwregs.c Date: Sun, 6 Nov 2011 22:13:02 +0100 Message-ID: <201111062213.02844.rjw@sisk.pl> References: <1320592697.7439.3.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1320592697.7439.3.camel@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org To: Rakib Mullick Cc: linux-kernel , linux-acpi , akpm@linux-foundation.org, ming Lin , len.brown@intel.com, srivatsa.bhat@linux.vnet.ibm.com, Len Brown , Linux PM list List-Id: linux-acpi@vger.kernel.org On Sunday, November 06, 2011, 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 > Cc: Lin Ming > Cc: Andrew Morton > Cc: Len Brown > Cc: Srivatsa S. Bhat Acked-by: Rafael J. Wysocki > --- > > 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-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >