[PATCH RFC 68/77] sfc: Update MSI/MSI-X interrupts enablement code

[Alexander Gordeev]

As result of recent re-design of the MSI/MSI-X interrupts enabling
pattern this driver has to be updated to use the new technique to
obtain a optimal number of MSI/MSI-X interrupts required.

Signed-off-by: Alexander Gordeev <agordeev at redhat.com>
---
 drivers/net/ethernet/sfc/efx.c |   18 +++++++++++-------
 1 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 07c9bc4..184ef9f 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1261,21 +1261,24 @@ static int efx_probe_interrupts(struct efx_nic *efx)
 		n_channels += extra_channels;
 		n_channels = min(n_channels, efx->max_channels);
 
-		for (i = 0; i < n_channels; i++)
-			xentries[i].entry = i;
-		rc = pci_enable_msix(efx->pci_dev, xentries, n_channels);
-		if (rc > 0) {
+		rc = pci_msix_table_size(efx->pci_dev);
+		if (rc < 0)
+			goto msi;
+
+		if (rc < n_channels) {
 			netif_err(efx, drv, efx->net_dev,
 				  "WARNING: Insufficient MSI-X vectors"
 				  " available (%d < %u).\n", rc, n_channels);
 			netif_err(efx, drv, efx->net_dev,
 				  "WARNING: Performance may be reduced.\n");
-			EFX_BUG_ON_PARANOID(rc >= n_channels);
 			n_channels = rc;
-			rc = pci_enable_msix(efx->pci_dev, xentries,
-					     n_channels);
 		}
 
+		EFX_BUG_ON_PARANOID(n_channels > ARRAY_SIZE(xentries));
+		for (i = 0; i < n_channels; i++)
+			xentries[i].entry = i;
+
+		rc = pci_enable_msix(efx->pci_dev, xentries, n_channels);
 		if (rc == 0) {
 			efx->n_channels = n_channels;
 			if (n_channels > extra_channels)
@@ -1293,6 +1296,7 @@ static int efx_probe_interrupts(struct efx_nic *efx)
 				efx_get_channel(efx, i)->irq =
 					xentries[i].vector;
 		} else {
+msi:
 			/* Fall back to single channel MSI */
 			efx->interrupt_mode = EFX_INT_MODE_MSI;
 			netif_err(efx, drv, efx->net_dev,
-- 
1.7.7.6