From: Stefan Assmann <sassmann@redhat.com>
Date: Fri, 18 Dec 2009 11:58:13 -0500
Subject: [pci] remove msi-x vector allocation limitation
Message-id: <4B2B6E55.5010903@redhat.com>
Patchwork-id: 22125
O-Subject: [RHEL 5.5 PATCH v3] pci: remove MSI-X vector allocation limitation
Bugzilla: 531266
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Don Dutile <ddutile@redhat.com>
RH-Acked-by: Andy Gospodarek <gospo@redhat.com>

Bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=531266

Description:
Removing nr_msix_devices from drivers/pci/msi.c along with the check
that limits the number of MSI-X vectors that can be allocated by a
driver. This check caused igb not to be able to allocate the requested
number of MSI-X vectors although there was a huge number of free
vectors left.
Check is completely removed as per davem's suggestion.
v2 addresses prarit's comment to remove nr_msix_devices.
v3 adding return statement requested by ddutile.

Upstream Status:
Code is a 2.6.18 legacy no longer present in upstream.

Brew Build:
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=2159067

Test Status:
Successfully tested-by-me. Unfortunately the main RDU QE lab has some
trouble and acquiring an IP from DHCP takes around 20s, so udhcpc in the
kdump initrd bails out long before that. STP is enabled on the
switch and I suspect this to be the problem. Anyway Evan will follow up
on this once they found out what's wrong.

  Stefan


diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 046866d..8d05a2f 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -30,7 +30,6 @@ static int pci_msi_enable = 1;
 static int last_alloc_vector;
 static int nr_released_vectors;
 static int nr_reserved_vectors = NR_HP_RESERVED_VECTORS;
-static int nr_msix_devices;
 
 #ifndef CONFIG_X86_IO_APIC
 int vector_irq[NR_VECTORS] = { [0 ... NR_VECTORS - 1] = -1};
@@ -503,7 +502,7 @@ void pci_scan_msi_device(struct pci_dev *dev)
 		return;
 
    	if (pci_find_capability(dev, PCI_CAP_ID_MSIX) > 0)
-		nr_msix_devices++;
+		return;
 	else if (pci_find_capability(dev, PCI_CAP_ID_MSI) > 0)
 		nr_reserved_vectors++;
 }
@@ -965,9 +964,6 @@ int pci_enable_msi(struct pci_dev* dev)
 	if (!status) {
    		if (!pos)
 			nr_reserved_vectors--;	/* Only MSI capable */
-		else if (nr_msix_devices > 0)
-			nr_msix_devices--;	/* Both MSI and MSI-X capable,
-						   but choose enabling MSI */
 	}
 
 	return status;
@@ -1131,9 +1127,6 @@ int pci_enable_msix(struct pci_dev* dev, struct msix_entry *entries, int nvec)
 	   default to avoid any MSI-X driver to take all available
  	   resources */
 	free_vectors -= nr_reserved_vectors;
-	/* Find the average of free vectors among MSI-X devices */
-	if (nr_msix_devices > 0)
-		free_vectors /= nr_msix_devices;
 	spin_unlock_irqrestore(&msi_lock, flags);
 
 	if (nvec > free_vectors) {
@@ -1144,8 +1137,6 @@ int pci_enable_msix(struct pci_dev* dev, struct msix_entry *entries, int nvec)
 	}
 
 	status = msix_capability_init(dev, entries, nvec);
-	if (!status && nr_msix_devices > 0)
-		nr_msix_devices--;
 
 	return status;
 }