scsi: qla2xxx: Fix memory leak when sending I/O fails

On heavy loads, a memory leak of the srb_t structure is observed.  This
would make the qla2xxx_srbs cache gobble up memory.

Fixes: 219d27d ("scsi: qla2xxx: Fix race conditions in the code for aborting SCSI commands")
Cc: stable@vger.kernel.org # 5.2
Link: https://lore.kernel.org/r/20191105150657.8092-7-hmadhani@marvell.com
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_os.c

@@ -909,6 +909,8 @@ qla2xxx_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 
 qc24_host_busy_free_sp:
 	sp->free(sp);
+	CMD_SP(cmd) = NULL;
+	qla2x00_rel_sp(sp);
 
 qc24_target_busy:
 	return SCSI_MLQUEUE_TARGET_BUSY;
@@ -992,6 +994,8 @@ qla2xxx_mqueuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd,
 
 qc24_host_busy_free_sp:
 	sp->free(sp);
+	CMD_SP(cmd) = NULL;
+	qla2xxx_rel_qpair_sp(sp->qpair, sp);
 
 qc24_target_busy:
 	return SCSI_MLQUEUE_TARGET_BUSY;