Re: [PATCH v3 02/23] ata: libata-core: Fix port and device removal

Niklas Cassel
2023-09-19T13:21:26Z

On Fri, Sep 15, 2023 at 05:14:46PM +0900, Damien Le Moal wrote:
> Whenever an ATA adapter driver is removed (e.g. rmmod),
> ata_port_detach() is called repeatedly for all the adapter ports to
> remove (unload) the devices attached to the port and delete the port
> device itself. Removing of devices is done using libata EH with the
> ATA_PFLAG_UNLOADING port flag set. This causes libata EH to execute
> ata_eh_unload() which disables all devices attached to the port.
>
> ata_port_detach() finishes by calling scsi_remove_host() to remove the
> scsi host associated with the port. This function will trigger the
> removal of all scsi devices attached to the host and in the case of
> disks, calls to sd_shutdown() which will flush the device write cache
> and stop the device. However, given that the devices were already
> disabled by ata_eh_unload(), the synchronize write cache command and
> start stop unit commands fail. E.g. running "rmmod ahci" with first
> removing sd_mod results in error messages like:
>
> ata13.00: disable device
> sd 0:0:0:0: [sda] Synchronizing SCSI cache
> sd 0:0:0:0: [sda] Synchronize Cache(10) failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
> sd 0:0:0:0: [sda] Stopping disk
> sd 0:0:0:0: [sda] Start/Stop Unit failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
>
> Fix this by removing all scsi devices of the ata devices connected to
> the port before scheduling libata EH to disable the ATA devices.
>
> Fixes: 720ba12620ee ("[PATCH] libata-hp: update unload-unplug")
> Cc: stable@vger.kernel.org
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> Reviewed-by: Hannes Reinecke <hare@suse.de>
> Tested-by: Chia-Lin Kao (AceLan) <acelan.kao@canonical.com>
> ---
> drivers/ata/libata-core.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index c4898483d716..693cb3cd70cd 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -5952,11 +5952,30 @@ static void ata_port_detach(struct ata_port *ap)
> struct ata_link *link;
> struct ata_device *dev;
>
> - /* tell EH we're leaving & flush EH */
> + /* Wait for any ongoing EH */
> + ata_port_wait_eh(ap);
> +
> + mutex_lock(&ap->scsi_scan_mutex);
> spin_lock_irqsave(ap->lock, flags);
> +
> + /* Remove scsi devices */
> + ata_for_each_link(link, ap, HOST_FIRST) {
> + ata_for_each_dev(dev, link, ALL) {
> + if (dev->sdev) {
> + spin_unlock_irqrestore(ap->lock, flags);
> + scsi_remove_device(dev->sdev);
> + spin_lock_irqsave(ap->lock, flags);
> + dev->sdev = NULL;
> + }
> + }
> + }
> +
> + /* Tell EH to disable all devices */
> ap->pflags |= ATA_PFLAG_UNLOADING;
> ata_port_schedule_eh(ap);
> +
> spin_unlock_irqrestore(ap->lock, flags);
> + mutex_unlock(&ap->scsi_scan_mutex);
>
> /* wait till EH commits suicide */
> ata_port_wait_eh(ap);
> --
> 2.41.0
>

Looks good:
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>

Could you perhaps also fix the WARN_ON(!(ap->pflags & ATA_PFLAG_UNLOADED));
in this very same function.

The pflag is checked without holding the lock.

Kind regards,
Niklas