[PATCH net-next 0/2] igb: fixes and improvements for irq fallback

[PATCH net-next 0/2] igb: fixes and improvements for irq fallback

[Stefan Assmann]

The interrupt fallback code should utilize the same code that's used for normal
setup instead of duplicating it. It also has some shortcomings when it comes
to situations where for some reason request_irq() fails to allocate vectors for
MSI-X. Hoping to address these with this patchset.

Would be nice for these patches to go through Intel testing before inclusion.

Stefan Assmann (2):
  igb: remove duplicate code for fallback interrupt initialization
  igb: release already assigned MSI-X interrupts if setup fails

-- 
1.7.11.7

[PATCH net-next 1/2] igb: remove duplicate code for fallback interrupt initialization

[Stefan Assmann]

Given a small change to igb_init_interrupt_scheme() the function fits
igb_request_irq() for MSI/legacy interrupts initialization as well, instead of
duplicating most of its code there.

Also adding a missing igb_configure() to igb_request_irq() for MSI fallback
to work properly.

Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index b85b15a..b0dd5ef 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -122,6 +122,7 @@ static void __devexit igb_remove(struct pci_dev *pdev);
 static int igb_sw_init(struct igb_adapter *);
 static int igb_open(struct net_device *);
 static int igb_close(struct net_device *);
+static void igb_configure(struct igb_adapter *);
 static void igb_configure_tx(struct igb_adapter *);
 static void igb_configure_rx(struct igb_adapter *);
 static void igb_clean_all_tx_rings(struct igb_adapter *);
@@ -948,11 +949,14 @@ static void igb_clear_interrupt_scheme(struct igb_adapter *adapter)
  * Attempt to configure interrupts using the best available
  * capabilities of the hardware and kernel.
  **/
-static void igb_set_interrupt_capability(struct igb_adapter *adapter)
+static void igb_set_interrupt_capability(struct igb_adapter *adapter, bool msix)
 {
 	int err;
 	int numvecs, i;
 
+	if (!msix)
+		goto msi_only;
+
 	/* Number of supported queues. */
 	adapter->num_rx_queues = adapter->rss_queues;
 	if (adapter->vfs_allocated_count)
@@ -1199,12 +1203,12 @@ err_out:
  *
  * This function initializes the interrupts and allocates all of the queues.
  **/
-static int igb_init_interrupt_scheme(struct igb_adapter *adapter)
+static int igb_init_interrupt_scheme(struct igb_adapter *adapter, bool msix)
 {
 	struct pci_dev *pdev = adapter->pdev;
 	int err;
 
-	igb_set_interrupt_capability(adapter);
+	igb_set_interrupt_capability(adapter, msix);
 
 	err = igb_alloc_q_vectors(adapter);
 	if (err) {
@@ -1240,20 +1244,15 @@ static int igb_request_irq(struct igb_adapter *adapter)
 		/* fall back to MSI */
 		igb_free_all_tx_resources(adapter);
 		igb_free_all_rx_resources(adapter);
+
 		igb_clear_interrupt_scheme(adapter);
-		if (!pci_enable_msi(pdev))
-			adapter->flags |= IGB_FLAG_HAS_MSI;
-		adapter->num_tx_queues = 1;
-		adapter->num_rx_queues = 1;
-		adapter->num_q_vectors = 1;
-		err = igb_alloc_q_vectors(adapter);
-		if (err) {
-			dev_err(&pdev->dev,
-			        "Unable to allocate memory for vectors\n");
+		err = igb_init_interrupt_scheme(adapter, false);
+		if (err)
 			goto request_done;
-		}
+
 		igb_setup_all_tx_resources(adapter);
 		igb_setup_all_rx_resources(adapter);
+		igb_configure(adapter);
 	}
 
 	igb_assign_vector(adapter->q_vector[0], 0);
@@ -2444,7 +2443,7 @@ static int __devinit igb_sw_init(struct igb_adapter *adapter)
 				GFP_ATOMIC);
 
 	/* This call may decrease the number of queues */
-	if (igb_init_interrupt_scheme(adapter)) {
+	if (igb_init_interrupt_scheme(adapter, true)) {
 		dev_err(&pdev->dev, "Unable to allocate memory for queues\n");
 		return -ENOMEM;
 	}
@@ -6818,7 +6817,7 @@ static int igb_resume(struct device *dev)
 	pci_enable_wake(pdev, PCI_D3hot, 0);
 	pci_enable_wake(pdev, PCI_D3cold, 0);
 
-	if (igb_init_interrupt_scheme(adapter)) {
+	if (igb_init_interrupt_scheme(adapter, true)) {
 		dev_err(&pdev->dev, "Unable to allocate memory for queues\n");
 		return -ENOMEM;
 	}
-- 
1.7.11.7

[PATCH net-next 2/2] igb: release already assigned MSI-X interrupts if setup fails

[Stefan Assmann]

During MSI-X setup the system might run out of vectors. If this happens the
already assigned vectors for this NIC should be freed before trying the
disable MSI-X. Failing to do so results in the following oops.

kernel BUG at drivers/pci/msi.c:341!
[...]
Call Trace:
 [<ffffffff8128f39d>] pci_disable_msix+0x3d/0x60
 [<ffffffffa037d1ce>] igb_reset_interrupt_capability+0x27/0x5c [igb]
 [<ffffffffa037d229>] igb_clear_interrupt_scheme+0x26/0x2d [igb]
 [<ffffffffa0384268>] igb_request_irq+0x73/0x297 [igb]
 [<ffffffffa0384554>] __igb_open+0xc8/0x223 [igb]
 [<ffffffffa0384815>] igb_open+0x13/0x15 [igb]
 [<ffffffff8144592f>] __dev_open+0xbf/0x120
 [<ffffffff81443e51>] __dev_change_flags+0xa1/0x180
 [<ffffffff81445828>] dev_change_flags+0x28/0x70
 [<ffffffff814af537>] devinet_ioctl+0x5b7/0x620
 [<ffffffff814b01c8>] inet_ioctl+0x88/0xa0
 [<ffffffff8142e8a0>] sock_do_ioctl+0x30/0x70
 [<ffffffff8142ecf2>] sock_ioctl+0x72/0x270
 [<ffffffff8118062c>] do_vfs_ioctl+0x8c/0x340
 [<ffffffff81180981>] sys_ioctl+0xa1/0xb0
 [<ffffffff815161a9>] system_call_fastpath+0x16/0x1b
Code: 48 89 df e8 1f 40 ed ff 4d 39 e6 49 8b 45 10 75 b6 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f c9 c3 48 8b 7b 20 e8 3e 91 db ff eb ae <0f> 0b eb fe 0f 1f 84 00 00 00 00 00 55 48 89 e5 0f 1f 44 00 00
RIP  [<ffffffff8128e144>] free_msi_irqs+0x124/0x130
 RSP <ffff880037503bd8>

Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index b0dd5ef..0007b97 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -832,17 +832,18 @@ static int igb_request_msix(struct igb_adapter *adapter)
 {
 	struct net_device *netdev = adapter->netdev;
 	struct e1000_hw *hw = &adapter->hw;
-	int i, err = 0, vector = 0;
+	int i, err = 0, vector = 0, free_vector = 0;
 
 	err = request_irq(adapter->msix_entries[vector].vector,
 	                  igb_msix_other, 0, netdev->name, adapter);
 	if (err)
-		goto out;
-	vector++;
+		goto err_out;
 
 	for (i = 0; i < adapter->num_q_vectors; i++) {
 		struct igb_q_vector *q_vector = adapter->q_vector[i];
 
+		vector++;
+
 		q_vector->itr_register = hw->hw_addr + E1000_EITR(vector);
 
 		if (q_vector->rx.ring && q_vector->tx.ring)
@@ -861,13 +862,22 @@ static int igb_request_msix(struct igb_adapter *adapter)
 		                  igb_msix_ring, 0, q_vector->name,
 		                  q_vector);
 		if (err)
-			goto out;
-		vector++;
+			goto err_free;
 	}
 
 	igb_configure_msix(adapter);
 	return 0;
-out:
+
+err_free:
+	/* free already assigned IRQs */
+	free_irq(adapter->msix_entries[free_vector++].vector, adapter);
+
+	vector--;
+	for (i = 0; i < vector; i++) {
+		free_irq(adapter->msix_entries[free_vector++].vector,
+			 adapter->q_vector[i]);
+	}
+err_out:
 	return err;
 }
 
-- 
1.7.11.7

Re: [PATCH net-next 0/2] igb: fixes and improvements for irq fallback

[Jeff Kirsher]

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On 12/03/2012 05:14 AM, Stefan Assmann wrote:
> The interrupt fallback code should utilize the same code that's used for normal
> setup instead of duplicating it. It also has some shortcomings when it comes
> to situations where for some reason request_irq() fails to allocate vectors for
> MSI-X. Hoping to address these with this patchset.
>
> Would be nice for these patches to go through Intel testing before inclusion.
>
> Stefan Assmann (2):
>   igb: remove duplicate code for fallback interrupt initialization
>   igb: release already assigned MSI-X interrupts if setup fails
>
Thanks Stefan, I have added the patches to my queue.


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