scsi: pm80xx: Fix race condition caused by static variables

Eliminate the use of static variables within the log pull implementation
to resolve a race condition and prevent data gaps when pulling logs from
multiple controllers in parallel, ensuring each operation is properly
isolated.

Signed-off-by: Francisco Gutierrez <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/pm8001/pm8001_ctl.c

···
 	char *str = buf;
 	u32 read_size =
 		pm8001_ha->main_cfg_tbl.pm80xx_tbl.event_log_size / 1024;
-	static u32 start, end, count;
 	u32 max_read_times = 32;
 	u32 max_count = (read_size * 1024) / (max_read_times * 4);
 	u32 *temp = (u32 *)pm8001_ha->memoryMap.region[IOP].virt_ptr;
 
-	if ((count % max_count) == 0) {
-		start = 0;
-		end = max_read_times;
-		count = 0;
+	mutex_lock(&pm8001_ha->iop_log_lock);
+
+	if ((pm8001_ha->iop_log_count % max_count) == 0) {
+		pm8001_ha->iop_log_start = 0;
+		pm8001_ha->iop_log_end = max_read_times;
+		pm8001_ha->iop_log_count = 0;
 	} else {
-		start = end;
-		end = end + max_read_times;
+		pm8001_ha->iop_log_start = pm8001_ha->iop_log_end;
+		pm8001_ha->iop_log_end = pm8001_ha->iop_log_end + max_read_times;
 	}
 
-	for (; start < end; start++)
-		str += sprintf(str, "%08x ", *(temp+start));
-	count++;
+	for (; pm8001_ha->iop_log_start < pm8001_ha->iop_log_end; pm8001_ha->iop_log_start++)
+		str += sprintf(str, "%08x ", *(temp+pm8001_ha->iop_log_start));
+	pm8001_ha->iop_log_count++;
+	mutex_unlock(&pm8001_ha->iop_log_lock);
 	return str - buf;
 }
 static DEVICE_ATTR(iop_log, S_IRUGO, pm8001_ctl_iop_log_show, NULL);

drivers/scsi/pm8001/pm8001_init.c

···
 	pm8001_ha->id = pm8001_id++;
 	pm8001_ha->logging_level = logging_level;
 	pm8001_ha->non_fatal_count = 0;
+	mutex_init(&pm8001_ha->iop_log_lock);
 	if (link_rate >= 1 && link_rate <= 15)
 		pm8001_ha->link_rate = (link_rate << 8);
 	else {

drivers/scsi/pm8001/pm8001_sas.h

···
 	u32 ci_offset;
 	u32 pi_offset;
 	u32 max_memcnt;
+	u32 iop_log_start;
+	u32 iop_log_end;
+	u32 iop_log_count;
+	struct mutex iop_log_lock;
 };
 
 struct pm8001_work {