Steffen Maier 42afc6527d scsi: zfcp: decouple TMFs from scsi_cmnd by using fc_block_rport ... Intentionally retrieve the rport by walking SCSI common code objects rather than zfcp_sdev->port->rport. The latter is used for pairing the calls to fc_remote_port_add() and fc_remote_port_delete(). [see v2.6.31 commit 379d6bf657 ("[SCSI] zfcp: Add port only once to FC transport class")] zfcp_scsi_rport_register() sets zfcp_port.rport to what fc_remote_port_add() returned. zfcp_scsi_rport_block() sets zfcp_port.rport = NULL after having called fc_remote_port_delete(). Hence, while an rport is blocked (or in any subsequent state due to scsi_transport_fc timeouts such as fast_io_fail_tmo or dev_loss_tmo), zfcp_port.rport is NULL and cannot serve as argument to fc_block_rport(). During zfcp recovery, a just recovered zfcp_port can have the UNBLOCKED status flag, but an async rport unblocking has only started via zfcp_scsi_schedule_rport_register() in zfcp_erp_try_rport_unblock() [see v4.10 commit 6f2ce1c6af ("scsi: zfcp: fix rport unblock race with LUN recovery")] in zfcp_erp_action_cleanup(). Now zfcp_erp_wait() can return. This would be sufficient to successfully send a TMF. But the rport can still be blocked and zfcp_port.rport can still be NULL until zfcp_port.rport_work was scheduled and has actually called fc_remote_port_add() and assigned its return value to zfcp_port.rport. We need an unblocked rport for a successful scsi_eh TUR. Similarly, for a zfcp_port which has just lost its UNBLOCKED status flag, the return of zfcp_erp_wait() can race with zfcp_port.rport_work queued by zfcp_scsi_schedule_rport_block(). Therefore we cannot reliably access zfcp_port.rport. However, we'd like to get fc_rport_block()'s opinion on when fast_io_fail_tmo triggered. While we might use flush_work(&port->rport_work) to sync with the work item, we can simply use the other way to get an rport pointer. Signed-off-by: Steffen Maier <maier@linux.ibm.com> Reviewed-by: Benjamin Block <bblock@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>		2018-05-18 11:22:11 -04:00
..
block	libnvdimm for 4.17	2018-04-10 10:25:57 -07:00
char	s390/defkeymap: fix global init to zero	2018-03-18 23:02:02 -07:00
cio	s390: assume diag308 set always works	2018-04-10 07:38:59 +02:00
crypto	s390/zcrypt: Support up to 256 crypto adapters.	2018-04-11 10:36:27 +02:00
net	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux	2018-04-09 09:04:10 -07:00
scsi	scsi: zfcp: decouple TMFs from scsi_cmnd by using fc_block_rport	2018-05-18 11:22:11 -04:00
virtio	virtio/s390: implement PM operations for virtio_ccw	2018-02-14 14:34:09 +02:00
Makefile	kbuild: rename built-in.o to built-in.a	2018-03-26 02:01:19 +09:00