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scsi: zfcp: drop duplicate fsf_command from zfcp_fsf_req which is also in QTCB header 

Status read buffers (SRBs, unsolicited notifications) never use a QTCB
[zfcp_fsf_req_create()]. zfcp_fsf_req_send() already uses this to
distinguish SRBs from other FSF request types. We can re-use this method in
zfcp_fsf_req_complete(). Introduce a helper function to make the check for
req->qtcb less magic.

SRBs always are FSF_QTCB_UNSOLICITED_STATUS, so we can hard-code this for
the two trace functions dealing with SRBs.

All other FSF request types have a QTCB and we can get the fsf_command from
there.

zfcp_dbf_hba_fsf_response() and thus zfcp_dbf_hba_fsf_res() are only called
for non-SRB requests so it's safe to dereference the QTCB
[zfcp_fsf_req_complete() returns early on SRB, else calls
zfcp_fsf_protstatus_eval() which calls zfcp_dbf_hba_fsf_response()].  In
zfcp_scsi_forget_cmnd() we guard the QTCB dereference with a preceding NULL
check and rely on boolean shortcut evaluation.

As a side effect, this causes an alignment hole which we can close in
a later patch after having cleaned up all fields of struct zfcp_fsf_req.
Before:
$ pahole -C zfcp_fsf_req drivers/s390/scsi/zfcp.ko
...
	u32                        status;               /*   136     4 */
	u32                        fsf_command;          /*   140     4 */
	struct fsf_qtcb *          qtcb;                 /*   144     8 */
...
After:
$ pahole -C zfcp_fsf_req drivers/s390/scsi/zfcp.ko
...
	u32                        status;               /*   136     4 */
	/* XXX 4 bytes hole, try to pack */
	struct fsf_qtcb *          qtcb;                 /*   144     8 */
...

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>
This commit is contained in:
Steffen Maier 2018-11-08 15:44:45 +01:00 committed by Martin K. Petersen
parent 2c53d8a0cc
commit f9eca02276
5 changed files with 20 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/s390/scsi/zfcp_dbf.c
View File

@ -81,7 +81,7 @@ void zfcp_dbf_hba_fsf_res(char *tag, int level, struct zfcp_fsf_req *req)
rec->id = ZFCP_DBF_HBA_RES;
rec->fsf_req_id = req->req_id;
rec->fsf_req_status = req->status;
rec->fsf_cmd = req->fsf_command;
rec->fsf_cmd = q_head->fsf_command;
rec->fsf_seq_no = req->seq_no;
rec->u.res.req_issued = req->issued;
rec->u.res.prot_status = q_pref->prot_status;
@ -94,7 +94,7 @@ void zfcp_dbf_hba_fsf_res(char *tag, int level, struct zfcp_fsf_req *req)
memcpy(rec->u.res.fsf_status_qual, &q_head->fsf_status_qual,
FSF_STATUS_QUALIFIER_SIZE);
if (req->fsf_command != FSF_QTCB_FCP_CMND) {
if (q_head->fsf_command != FSF_QTCB_FCP_CMND) {
rec->pl_len = q_head->log_length;
zfcp_dbf_pl_write(dbf, (char *)q_pref + q_head->log_start,
rec->pl_len, "fsf_res", req->req_id);
@ -127,7 +127,7 @@ void zfcp_dbf_hba_fsf_uss(char *tag, struct zfcp_fsf_req *req)
rec->id = ZFCP_DBF_HBA_USS;
rec->fsf_req_id = req->req_id;
rec->fsf_req_status = req->status;
rec->fsf_cmd = req->fsf_command;
rec->fsf_cmd = FSF_QTCB_UNSOLICITED_STATUS;
if (!srb)
goto log;
@ -174,7 +174,7 @@ void zfcp_dbf_hba_bit_err(char *tag, struct zfcp_fsf_req *req)
rec->id = ZFCP_DBF_HBA_BIT;
rec->fsf_req_id = req->req_id;
rec->fsf_req_status = req->status;
rec->fsf_cmd = req->fsf_command;
rec->fsf_cmd = FSF_QTCB_UNSOLICITED_STATUS;
memcpy(&rec->u.be, &sr_buf->payload.bit_error,
sizeof(struct fsf_bit_error_payload));

4
drivers/s390/scsi/zfcp_dbf.h
View File

@ -339,8 +339,8 @@ void zfcp_dbf_hba_fsf_response(struct zfcp_fsf_req *req)
zfcp_dbf_hba_fsf_resp_suppress(req)
? 5 : 1, req);
} else if ((req->fsf_command == FSF_QTCB_OPEN_PORT_WITH_DID) ||
(req->fsf_command == FSF_QTCB_OPEN_LUN)) {
} else if ((qtcb->header.fsf_command == FSF_QTCB_OPEN_PORT_WITH_DID) ||
(qtcb->header.fsf_command == FSF_QTCB_OPEN_LUN)) {
zfcp_dbf_hba_fsf_resp("fs_open", 4, req);
} else if (qtcb->header.log_length) {

7
drivers/s390/scsi/zfcp_def.h
View File

@ -277,7 +277,6 @@ static inline u64 zfcp_scsi_dev_lun(struct scsi_device *sdev)
* @qdio_req: qdio queue related values
* @completion: used to signal the completion of the request
* @status: status of the request
* @fsf_command: FSF command issued
* @qtcb: associated QTCB
* @seq_no: sequence number of this request
* @data: private data
@ -294,7 +293,6 @@ struct zfcp_fsf_req {
struct zfcp_qdio_req qdio_req;
struct completion completion;
u32 status;
u32 fsf_command;
struct fsf_qtcb *qtcb;
u32 seq_no;
void *data;
@ -311,4 +309,9 @@ int zfcp_adapter_multi_buffer_active(struct zfcp_adapter *adapter)
return atomic_read(&adapter->status) & ZFCP_STATUS_ADAPTER_MB_ACT;
}
static inline bool zfcp_fsf_req_is_status_read_buffer(struct zfcp_fsf_req *req)
{
return req->qtcb == NULL;
}
#endif /* ZFCP_DEF_H */

14
drivers/s390/scsi/zfcp_fsf.c
View File

@ -84,13 +84,13 @@ static void zfcp_fsf_class_not_supp(struct zfcp_fsf_req *req)
void zfcp_fsf_req_free(struct zfcp_fsf_req *req)
{
if (likely(req->pool)) {
if (likely(req->qtcb))
if (likely(!zfcp_fsf_req_is_status_read_buffer(req)))
mempool_free(req->qtcb, req->adapter->pool.qtcb_pool);
mempool_free(req, req->pool);
return;
}
if (likely(req->qtcb))
if (likely(!zfcp_fsf_req_is_status_read_buffer(req)))
kmem_cache_free(zfcp_fsf_qtcb_cache, req->qtcb);
kfree(req);
}
@ -393,7 +393,7 @@ static void zfcp_fsf_protstatus_eval(struct zfcp_fsf_req *req)
*/
static void zfcp_fsf_req_complete(struct zfcp_fsf_req *req)
{
if (unlikely(req->fsf_command == FSF_QTCB_UNSOLICITED_STATUS)) {
if (unlikely(zfcp_fsf_req_is_status_read_buffer(req))) {
zfcp_fsf_status_read_handler(req);
return;
}
@ -710,7 +710,6 @@ static struct zfcp_fsf_req *zfcp_fsf_req_create(struct zfcp_qdio *qdio,
init_completion(&req->completion);
req->adapter = adapter;
req->fsf_command = fsf_cmd;
req->req_id = adapter->req_no;
if (likely(fsf_cmd != FSF_QTCB_UNSOLICITED_STATUS)) {
@ -729,10 +728,10 @@ static struct zfcp_fsf_req *zfcp_fsf_req_create(struct zfcp_qdio *qdio,
req->qtcb->prefix.req_seq_no = adapter->fsf_req_seq_no;
req->qtcb->prefix.req_id = req->req_id;
req->qtcb->prefix.ulp_info = 26;
req->qtcb->prefix.qtcb_type = fsf_qtcb_type[req->fsf_command];
req->qtcb->prefix.qtcb_type = fsf_qtcb_type[fsf_cmd];
req->qtcb->prefix.qtcb_version = FSF_QTCB_CURRENT_VERSION;
req->qtcb->header.req_handle = req->req_id;
req->qtcb->header.fsf_command = req->fsf_command;
req->qtcb->header.fsf_command = fsf_cmd;
}
zfcp_qdio_req_init(adapter->qdio, &req->qdio_req, req->req_id, sbtype,
@ -745,7 +744,6 @@ static int zfcp_fsf_req_send(struct zfcp_fsf_req *req)
{
struct zfcp_adapter *adapter = req->adapter;
struct zfcp_qdio *qdio = adapter->qdio;
int with_qtcb = (req->qtcb != NULL);
int req_id = req->req_id;
zfcp_reqlist_add(adapter->req_list, req);
@ -761,7 +759,7 @@ static int zfcp_fsf_req_send(struct zfcp_fsf_req *req)
}
/* Don't increase for unsolicited status */
if (with_qtcb)
if (!zfcp_fsf_req_is_status_read_buffer(req))
adapter->fsf_req_seq_no++;
adapter->req_no++;

4
drivers/s390/scsi/zfcp_scsi.c
View File

@ -226,7 +226,9 @@ static void zfcp_scsi_forget_cmnd(struct zfcp_fsf_req *old_req, void *data)
(struct zfcp_scsi_req_filter *)data;
/* already aborted - prevent side-effects - or not a SCSI command */
if (old_req->data == NULL || old_req->fsf_command != FSF_QTCB_FCP_CMND)
if (old_req->data == NULL ||
zfcp_fsf_req_is_status_read_buffer(old_req) ||
old_req->qtcb->header.fsf_command != FSF_QTCB_FCP_CMND)
return;
/* (tmf_scope == FCP_TMF_TGT_RESET || tmf_scope == FCP_TMF_LUN_RESET) */