get_device() and its internally used kobject_get() only return NULL if they get passed NULL as argument. zfcp_get_port_by_wwpn() loops over adapter->port_list so the iteration variable port is always non-NULL. Struct device is embedded in struct zfcp_port so &port->dev is always non-NULL. This is the argument to get_device(). However, if we get an fc_rport in terminate_rport_io() for which we cannot find a match within zfcp_get_port_by_wwpn(), the latter can return NULL. v2.6.30 commit 70932935b61e ("[SCSI] zfcp: Fix oops when port disappears") introduced an early return without adding a trace record for this case. Even if we don't need recovery in this case, for debugging we should still see that our callback was invoked originally by scsi_transport_fc.

Example trace record formatted with zfcpdbf from s390-tools:

Timestamp : ... Area : REC Subarea : 00 Level : 1 Exception : - CPU ID : .. Caller : 0x... Record ID : 1 Tag : sctrpin SCSI terminate rport I/O, no zfcp port LUN : 0xffffffffffffffff none (invalid) WWPN : 0x<wwpn> WWPN D_ID : 0x<n_port_id> N_Port-ID Adapter status : 0x... Port status : 0xffffffff unknown (-1) LUN status : 0x00000000 none (invalid) Ready count : 0x... Running count : 0x... ERP want : 0x03 ZFCP_ERP_ACTION_REOPEN_PORT_FORCED ERP need : 0xc0 ZFCP_ERP_ACTION_NONE

Signed-off-by: Steffen Maier maier@linux.ibm.com Fixes: 70932935b61e ("[SCSI] zfcp: Fix oops when port disappears") Cc: stable@vger.kernel.org #2.6.38+ Reviewed-by: Benjamin Block bblock@linux.ibm.com --- drivers/s390/scsi/zfcp_erp.c | 20 ++++++++++++++++++++ drivers/s390/scsi/zfcp_ext.h | 3 +++ drivers/s390/scsi/zfcp_scsi.c | 5 +++++ 3 files changed, 28 insertions(+)

diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c index d9cd25b56cfa..3489b1bc9121 100644 --- a/drivers/s390/scsi/zfcp_erp.c +++ b/drivers/s390/scsi/zfcp_erp.c @@ -283,6 +283,26 @@ static int zfcp_erp_action_enqueue(int want, struct zfcp_adapter *adapter, return retval; }

+void zfcp_erp_port_forced_no_port_dbf(char *id, struct zfcp_adapter *adapter, + u64 port_name, u32 port_id) +{ + unsigned long flags; + static /* don't waste stack */ struct zfcp_port tmpport; + + write_lock_irqsave(&adapter->erp_lock, flags); + /* Stand-in zfcp port with fields just good enough for + * zfcp_dbf_rec_trig() and zfcp_dbf_set_common(). + * Under lock because tmpport is static. + */ + atomic_set(&tmpport.status, -1); /* unknown */ + tmpport.wwpn = port_name; + tmpport.d_id = port_id; + zfcp_dbf_rec_trig(id, adapter, &tmpport, NULL, + ZFCP_ERP_ACTION_REOPEN_PORT_FORCED, + ZFCP_ERP_ACTION_NONE); + write_unlock_irqrestore(&adapter->erp_lock, flags); +} + static int _zfcp_erp_adapter_reopen(struct zfcp_adapter *adapter, int clear_mask, char *id) { diff --git a/drivers/s390/scsi/zfcp_ext.h b/drivers/s390/scsi/zfcp_ext.h index e55f42ce1168..3299bd345076 100644 --- a/drivers/s390/scsi/zfcp_ext.h +++ b/drivers/s390/scsi/zfcp_ext.h @@ -55,6 +55,9 @@ extern void zfcp_dbf_scsi_eh(char *tag, struct zfcp_adapter *adapter, /* zfcp_erp.c */ extern void zfcp_erp_set_adapter_status(struct zfcp_adapter *, u32); extern void zfcp_erp_clear_adapter_status(struct zfcp_adapter *, u32); +extern void zfcp_erp_port_forced_no_port_dbf(char *id, + struct zfcp_adapter *adapter, + u64 port_name, u32 port_id); extern void zfcp_erp_adapter_reopen(struct zfcp_adapter *, int, char *); extern void zfcp_erp_adapter_shutdown(struct zfcp_adapter *, int, char *); extern void zfcp_erp_set_port_status(struct zfcp_port *, u32); diff --git a/drivers/s390/scsi/zfcp_scsi.c b/drivers/s390/scsi/zfcp_scsi.c index 4fdb1665b0e6..478e7ef9ea2f 100644 --- a/drivers/s390/scsi/zfcp_scsi.c +++ b/drivers/s390/scsi/zfcp_scsi.c @@ -605,6 +605,11 @@ static void zfcp_scsi_terminate_rport_io(struct fc_rport *rport) if (port) { zfcp_erp_port_forced_reopen(port, 0, "sctrpi1"); put_device(&port->dev); + } else { + zfcp_erp_port_forced_no_port_dbf( + "sctrpin", adapter, + rport->port_name /* zfcp_scsi_rport_register */, + rport->port_id /* zfcp_scsi_rport_register */); } }