netdev - [PATCH net-next 3/3] net/mlx4_core: Use msi_x module param to limit num of MSI-X irqs

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Date:   Wed,  9 May 2018 18:29:04 +0300
From:   Tariq Toukan <tariqt@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Eran Ben Elisha <eranbe@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Ajaykumar Hotchandani <ajaykumar.hotchandani@...cle.com>
Subject: [PATCH net-next 3/3] net/mlx4_core: Use msi_x module param to limit num of MSI-X irqs

Extend the boolean interpretation of msi_x module parameter
to numerical, as follows:

0   - Don't use MSI-X.
1   - Use MSI-X, driver decides the num of MSI-X irqs.
>=2 - Use MSI-X, limit number of MSI-X irqs to msi_x.
      In SRIOV, this limits the number of MSI-X irqs per VF.

Signed-off-by: Tariq Toukan <tariqt@...lanox.com>
Cc: Ajaykumar Hotchandani <ajaykumar.hotchandani@...cle.com>
---
 drivers/net/ethernet/mellanox/mlx4/main.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/main.c b/drivers/net/ethernet/mellanox/mlx4/main.c
index b6aaf34d6648..80a75c80a463 100644
--- a/drivers/net/ethernet/mellanox/mlx4/main.c
+++ b/drivers/net/ethernet/mellanox/mlx4/main.c
@@ -73,7 +73,7 @@
 
 static int msi_x = 1;
 module_param(msi_x, int, 0444);
-MODULE_PARM_DESC(msi_x, "attempt to use MSI-X if nonzero");
+MODULE_PARM_DESC(msi_x, "0 - don't use MSI-X, 1 - use MSI-X, >1 - limit number of MSI-X irqs to msi_x");
 
 #else /* CONFIG_PCI_MSI */
 
@@ -2815,6 +2815,9 @@ static void mlx4_enable_msi_x(struct mlx4_dev *dev)
 				dev->caps.num_eqs - dev->caps.reserved_eqs,
 				MAX_MSIX);
 
+		if (msi_x > 1)
+			nreq = min_t(int, nreq, msi_x);
+
 		entries = kcalloc(nreq, sizeof(*entries), GFP_KERNEL);
 		if (!entries)
 			goto no_msi;
@@ -4182,6 +4185,11 @@ static int mlx4_resume(struct pci_dev *pdev)
 
 static int __init mlx4_verify_params(void)
 {
+	if (msi_x < 0) {
+		pr_warn("mlx4_core: bad msi_x: %d\n", msi_x);
+		return -1;
+	}
+
 	if ((log_num_mac < 0) || (log_num_mac > 7)) {
 		pr_warn("mlx4_core: bad num_mac: %d\n", log_num_mac);
 		return -1;
-- 
1.8.3.1