cxgb4: fix adapter crash due to wrong MC size

In the absence of MC1, the size calculation function
cudbg_mem_region_size() was returing wrong MC size and
resulted in adapter crash. This patch adds new argument
to cudbg_mem_region_size() which will have actual size
and returns error to caller in the absence of MC1.

Fixes: a1c69520 ("cxgb4: collect MC memory dump")
Signed-off-by: Vishal Kulkarni <vishal@chelsio.com>"
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c

@@ -1049,9 +1049,9 @@ static void cudbg_t4_fwcache(struct cudbg_init *pdbg_init,
 	}
 }
 
-static unsigned long cudbg_mem_region_size(struct cudbg_init *pdbg_init,
-					   struct cudbg_error *cudbg_err,
-					   u8 mem_type)
+static int cudbg_mem_region_size(struct cudbg_init *pdbg_init,
+				 struct cudbg_error *cudbg_err,
+				 u8 mem_type, unsigned long *region_size)
 {
 	struct adapter *padap = pdbg_init->adap;
 	struct cudbg_meminfo mem_info;
@@ -1060,15 +1060,23 @@ static unsigned long cudbg_mem_region_size(struct cudbg_init *pdbg_init,
 
 	memset(&mem_info, 0, sizeof(struct cudbg_meminfo));
 	rc = cudbg_fill_meminfo(padap, &mem_info);
-	if (rc)
+	if (rc) {
+		cudbg_err->sys_err = rc;
 		return rc;
+	}
 
 	cudbg_t4_fwcache(pdbg_init, cudbg_err);
 	rc = cudbg_meminfo_get_mem_index(padap, &mem_info, mem_type, &mc_idx);
-	if (rc)
+	if (rc) {
+		cudbg_err->sys_err = rc;
 		return rc;
+	}
+
+	if (region_size)
+		*region_size = mem_info.avail[mc_idx].limit -
+			       mem_info.avail[mc_idx].base;
 
-	return mem_info.avail[mc_idx].limit - mem_info.avail[mc_idx].base;
+	return 0;
 }
 
 static int cudbg_collect_mem_region(struct cudbg_init *pdbg_init,
@@ -1076,7 +1084,12 @@ static int cudbg_collect_mem_region(struct cudbg_init *pdbg_init,
 				    struct cudbg_error *cudbg_err,
 				    u8 mem_type)
 {
-	unsigned long size = cudbg_mem_region_size(pdbg_init, cudbg_err, mem_type);
+	unsigned long size = 0;
+	int rc;
+
+	rc = cudbg_mem_region_size(pdbg_init, cudbg_err, mem_type, &size);
+	if (rc)
+		return rc;
 
 	return cudbg_read_fw_mem(pdbg_init, dbg_buff, mem_type, size,
 				 cudbg_err);