From: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Date: Fri, 2 Aug 2019 01:25:23 -0700
Subject: ice: Rework ice_ena_msix_range
Patch-mainline: v5.4-rc1
Git-commit: 152b978a1f904f252ae3df548bc2e183e7368c6d
References: jsc#SLE-7926

The current implementation of ice_ena_msix_range is difficult to read
and has subtle issues. This patch reworks the said function for
clarity and correctness.

More specifically,

1. Add more checks to bail out of 'needed' is greater than 'v_left'.

2. Simplify fallback logic

3. Do not set pf->num_avail_sw_msix in ice_ena_msix_range as it
   gets overwritten by ice_init_interrupt_scheme.

Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/ice/ice_main.c |   32 +++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -2281,13 +2281,18 @@ static int ice_ena_msix_range(struct ice
 
 	/* reserve one vector for miscellaneous handler */
 	needed = 1;
+	if (v_left < needed)
+		goto no_hw_vecs_left_err;
 	v_budget += needed;
 	v_left -= needed;
 
 	/* reserve vectors for LAN traffic */
-	pf->num_lan_msix = min_t(int, num_online_cpus(), v_left);
-	v_budget += pf->num_lan_msix;
-	v_left -= pf->num_lan_msix;
+	needed = min_t(int, num_online_cpus(), v_left);
+	if (v_left < needed)
+		goto no_hw_vecs_left_err;
+	pf->num_lan_msix = needed;
+	v_budget += needed;
+	v_left -= needed;
 
 	pf->msix_entries = devm_kcalloc(&pf->pdev->dev, v_budget,
 					sizeof(*pf->msix_entries), GFP_KERNEL);
@@ -2312,18 +2317,18 @@ static int ice_ena_msix_range(struct ice
 
 	if (v_actual < v_budget) {
 		dev_warn(&pf->pdev->dev,
-			 "not enough vectors. requested = %d, obtained = %d\n",
+			 "not enough OS MSI-X vectors. requested = %d, obtained = %d\n",
 			 v_budget, v_actual);
-		if (v_actual >= (pf->num_lan_msix + 1)) {
-			pf->num_avail_sw_msix = v_actual -
-						(pf->num_lan_msix + 1);
-		} else if (v_actual >= 2) {
-			pf->num_lan_msix = 1;
-			pf->num_avail_sw_msix = v_actual - 2;
-		} else {
+/* 2 vectors for LAN (traffic + OICR) */
+#define ICE_MIN_LAN_VECS 2
+
+		if (v_actual < ICE_MIN_LAN_VECS) {
+			/* error if we can't get minimum vectors */
 			pci_disable_msix(pf->pdev);
 			err = -ERANGE;
 			goto msix_err;
+		} else {
+			pf->num_lan_msix = ICE_MIN_LAN_VECS;
 		}
 	}
 
@@ -2333,6 +2338,11 @@ msix_err:
 	devm_kfree(&pf->pdev->dev, pf->msix_entries);
 	goto exit_err;
 
+no_hw_vecs_left_err:
+	dev_err(&pf->pdev->dev,
+		"not enough device MSI-X vectors. requested = %d, available = %d\n",
+		needed, v_left);
+	err = -ERANGE;
 exit_err:
 	pf->num_lan_msix = 0;
 	return err;