[PATCH v3 2/2] ata: libata: Defer rescan on suspended device

[PATCH v3 2/2] ata: libata: Defer rescan on suspended device

[Kai-Heng Feng]

During system resume, if an EH is schduled after ATA host is resumed
(i.e. ATA_PFLAG_PM_PENDING cleared), but before the disk device is
fully resumed, the device_lock hold by scsi_rescan_device() is never
released so the dpm_resume() of the disk is blocked forerver.

That's because scsi_attach_vpd() is expecting the disk device is in
operational state, as it doesn't work on suspended device.

To avoid such deadlock, defer rescan if the disk is still suspended so
the resume process of the disk device can proceed. At the end of the
resume process, use the complete() callback to schedule the rescan task.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v3:
 - New patch to resolve undefined pm_suspend_target_state.

v2:
 - Schedule rescan task at the end of system resume phase.
 - Wording.

 drivers/ata/libata-core.c | 11 +++++++++++
 drivers/ata/libata-eh.c   | 11 +++++++++--
 include/linux/libata.h    |  1 +
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 14c17c3bda4e..564d72bf1ec6 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5093,6 +5093,16 @@ static int ata_port_pm_poweroff(struct device *dev)
 	return 0;
 }
 
+static void ata_port_pm_complete(struct device *dev)
+{
+	struct ata_port *ap = to_ata_port(dev);
+
+	if (ap->pflags & ATA_PFLAG_DEFER_RESCAN)
+		schedule_work(&(ap->scsi_rescan_task));
+
+	ap->pflags &= ~ATA_PFLAG_DEFER_RESCAN;
+}
+
 static const unsigned int ata_port_resume_ehi = ATA_EHI_NO_AUTOPSY
 						| ATA_EHI_QUIET;
 
@@ -5158,6 +5168,7 @@ static const struct dev_pm_ops ata_port_pm_ops = {
 	.thaw = ata_port_pm_resume,
 	.poweroff = ata_port_pm_poweroff,
 	.restore = ata_port_pm_resume,
+	.complete = ata_port_pm_complete,
 
 	.runtime_suspend = ata_port_runtime_suspend,
 	.runtime_resume = ata_port_runtime_resume,
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index a6c901811802..0881b590fb7e 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -15,6 +15,7 @@
 #include <linux/blkdev.h>
 #include <linux/export.h>
 #include <linux/pci.h>
+#include <linux/suspend.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_eh.h>
@@ -2983,8 +2984,14 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
 			 */
 			ehc->i.flags |= ATA_EHI_SETMODE;
 
-			/* schedule the scsi_rescan_device() here */
-			schedule_work(&(ap->scsi_rescan_task));
+			/* Schedule the scsi_rescan_device() here.
+			 * Defer the rescan if it's in process of
+			 * suspending or resuming.
+			 */
+			if (pm_suspend_target_state != PM_SUSPEND_ON)
+				ap->pflags |= ATA_PFLAG_DEFER_RESCAN;
+			else
+				schedule_work(&(ap->scsi_rescan_task));
 		} else if (dev->class == ATA_DEV_UNKNOWN &&
 			   ehc->tries[dev->devno] &&
 			   ata_class_enabled(ehc->classes[dev->devno])) {
diff --git a/include/linux/libata.h b/include/linux/libata.h
index a759dfbdcc91..aaa549444abc 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -189,6 +189,7 @@ enum {
 	ATA_PFLAG_UNLOADING	= (1 << 9), /* driver is being unloaded */
 	ATA_PFLAG_UNLOADED	= (1 << 10), /* driver is unloaded */
 
+	ATA_PFLAG_DEFER_RESCAN	= (1 << 16), /* peform deferred rescan on system resume */
 	ATA_PFLAG_SUSPENDED	= (1 << 17), /* port is suspended (power) */
 	ATA_PFLAG_PM_PENDING	= (1 << 18), /* PM operation pending */
 	ATA_PFLAG_INIT_GTM_VALID = (1 << 19), /* initial gtm data valid */
-- 
2.34.1

Re: [PATCH v3 2/2] ata: libata: Defer rescan on suspended device

[kernel test robot]

Hi Kai-Heng,

kernel test robot noticed the following build errors:

[auto build test ERROR on rafael-pm/linux-next]
[also build test ERROR on linus/master v6.3 next-20230426]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Kai-Heng-Feng/ata-libata-Defer-rescan-on-suspended-device/20230427-130726
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
patch link:    https://lore.kernel.org/r/20230427050603.612145-2-kai.heng.feng%40canonical.com
patch subject: [PATCH v3 2/2] ata: libata: Defer rescan on suspended device
config: i386-randconfig-a005 (https://download.01.org/0day-ci/archive/20230427/202304271800.2IH4Swv7-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/0e5dc37a85d9e0c92e2ae38903928499b2b17d04
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Kai-Heng-Feng/ata-libata-Defer-rescan-on-suspended-device/20230427-130726
        git checkout 0e5dc37a85d9e0c92e2ae38903928499b2b17d04
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304271800.2IH4Swv7-lkp@intel.com/

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "pm_suspend_target_state" [drivers/ata/libata.ko] undefined!

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

Re: [PATCH v3 2/2] ata: libata: Defer rescan on suspended device

[kernel test robot]

Hi Kai-Heng,

kernel test robot noticed the following build errors:

[auto build test ERROR on rafael-pm/linux-next]
[also build test ERROR on linus/master pavel-leds/for-next v6.3 next-20230426]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Kai-Heng-Feng/ata-libata-Defer-rescan-on-suspended-device/20230427-130726
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
patch link:    https://lore.kernel.org/r/20230427050603.612145-2-kai.heng.feng%40canonical.com
patch subject: [PATCH v3 2/2] ata: libata: Defer rescan on suspended device
config: mips-randconfig-r014-20230427 (https://download.01.org/0day-ci/archive/20230427/202304271942.yVqlIimT-lkp@intel.com/config)
compiler: mipsel-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/0e5dc37a85d9e0c92e2ae38903928499b2b17d04
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Kai-Heng-Feng/ata-libata-Defer-rescan-on-suspended-device/20230427-130726
        git checkout 0e5dc37a85d9e0c92e2ae38903928499b2b17d04
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=mips olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304271942.yVqlIimT-lkp@intel.com/

All errors (new ones prefixed by >>):

   mipsel-linux-ld: drivers/ata/libata-eh.o: in function `ata_eh_revalidate_and_attach':
>> libata-eh.c:(.text.ata_eh_revalidate_and_attach+0x74): undefined reference to `pm_suspend_target_state'
>> mipsel-linux-ld: libata-eh.c:(.text.ata_eh_revalidate_and_attach+0x1f8): undefined reference to `pm_suspend_target_state'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests