[PATCH 3.16 063/366] scsi: zfcp: fix missing REC trigger trace on terminate_rport_io early return

Ben Hutchings
2018-11-11T20:06:53Z

From: Steffen Maier <maier@linux.ibm.com>

commit 96d9270499471545048ed8a6d7f425a49762283d upstream.

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")
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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(+)

--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -282,6 +282,26 @@ static int zfcp_erp_action_enqueue(int w
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)
{
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -58,6 +58,9 @@ extern void zfcp_dbf_scsi_eh(char *tag,
/* 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);
--- a/drivers/s390/scsi/zfcp_scsi.c
+++ b/drivers/s390/scsi/zfcp_scsi.c
@@ -624,6 +624,11 @@ static void zfcp_scsi_terminate_rport_io
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 */);
}
}