i40e: fix registers dump after run ethtool adapter self test

Fix invalid registers dump from ethtool -d ethX after adapter self test
by ethtool -t ethY. It causes invalid data display.

The problem was caused by overwriting i40e_reg_list[].elements
which is common for ethtool self test and dump.

Fixes: 22dd9ae ("i40e: Rework register diagnostic")
Signed-off-by: Radoslaw Tyl <radoslawx.tyl@intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20230328172659.3906413-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: rtylx

drivers/net/ethernet/intel/i40e/i40e_diag.c

@@ -44,7 +44,7 @@ static int i40e_diag_reg_pattern_test(struct i40e_hw *hw,
 	return 0;
 }
 
-struct i40e_diag_reg_test_info i40e_reg_list[] = {
+const struct i40e_diag_reg_test_info i40e_reg_list[] = {
 	/* offset               mask         elements   stride */
 	{I40E_QTX_CTL(0),       0x0000FFBF, 1,
 		I40E_QTX_CTL(1) - I40E_QTX_CTL(0)},
@@ -78,27 +78,28 @@ int i40e_diag_reg_test(struct i40e_hw *hw)
 {
 	int ret_code = 0;
 	u32 reg, mask;
+	u32 elements;
 	u32 i, j;
 
 	for (i = 0; i40e_reg_list[i].offset != 0 &&
 					     !ret_code; i++) {
 
+		elements = i40e_reg_list[i].elements;
 		/* set actual reg range for dynamically allocated resources */
 		if (i40e_reg_list[i].offset == I40E_QTX_CTL(0) &&
 		    hw->func_caps.num_tx_qp != 0)
-			i40e_reg_list[i].elements = hw->func_caps.num_tx_qp;
+			elements = hw->func_caps.num_tx_qp;
 		if ((i40e_reg_list[i].offset == I40E_PFINT_ITRN(0, 0) ||
 		     i40e_reg_list[i].offset == I40E_PFINT_ITRN(1, 0) ||
 		     i40e_reg_list[i].offset == I40E_PFINT_ITRN(2, 0) ||
 		     i40e_reg_list[i].offset == I40E_QINT_TQCTL(0) ||
 		     i40e_reg_list[i].offset == I40E_QINT_RQCTL(0)) &&
 		    hw->func_caps.num_msix_vectors != 0)
-			i40e_reg_list[i].elements =
-				hw->func_caps.num_msix_vectors - 1;
+			elements = hw->func_caps.num_msix_vectors - 1;
 
 		/* test register access */
 		mask = i40e_reg_list[i].mask;
-		for (j = 0; j < i40e_reg_list[i].elements && !ret_code; j++) {
+		for (j = 0; j < elements && !ret_code; j++) {
 			reg = i40e_reg_list[i].offset +
 			      (j * i40e_reg_list[i].stride);
 			ret_code = i40e_diag_reg_pattern_test(hw, reg, mask);

drivers/net/ethernet/intel/i40e/i40e_diag.h

@@ -20,7 +20,7 @@ struct i40e_diag_reg_test_info {
 	u32 stride;	/* bytes between each element */
 };
 
-extern struct i40e_diag_reg_test_info i40e_reg_list[];
+extern const struct i40e_diag_reg_test_info i40e_reg_list[];
 
 int i40e_diag_reg_test(struct i40e_hw *hw);
 int i40e_diag_eeprom_test(struct i40e_hw *hw);