Patchwork skge: use unique IRQ name

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Submitter Michal Schmidt
Date Oct. 1, 2009, 10:27 a.m.
Message ID <20091001122720.3822bdd3@leela>
Download mbox | patch
Permalink /patch/34666/
State Changes Requested
Delegated to: David Miller
Headers show

Comments

Michal Schmidt - Oct. 1, 2009, 10:27 a.m.
Most network drivers request their IRQ when the interface is activated.
skge does it in ->probe() instead, because it can work with two-port
cards where the two net_devices use the same IRQ. This works fine most
of the time, except in some situations when the interface gets renamed.
Consider this example:

1. modprobe skge
   The card is detected as eth0 and requests IRQ 17. Directory
   /proc/irq/17/eth0 is created.
2. There is an udev rule which says this interface should be called
   eth1, so udev renames eth0 -> eth1.
3. modprobe 8139too
   The Realtek card is detected as eth0. It will be using IRQ 17 too.
4. ip link set eth0 up
   Now 8139too requests IRQ 17.

The result is:
WARNING: at fs/proc/generic.c:590 proc_register ...
proc_dir_entry '17/eth0' already registered
...
And "ls /proc/irq/17" shows two subdirectories, both called eth0.

Fix it by using a unique name for skge's IRQ, based on the PCI address.
The naming from the example then looks like this:
$ grep skge /proc/interrupts
 17:        169   IO-APIC-fasteoi   skge@0000:00:0a.0, eth0

irqbalance daemon will have to be taught to recognize "skge@" as an
Ethernet interrupt. This will be a one-liner addition in classify.c. I
will send a patch to irqbalance if this change is accepted.

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>

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stephen hemminger - Oct. 1, 2009, 4:06 p.m.
On Thu, 1 Oct 2009 12:27:20 +0200
Michal Schmidt <mschmidt@redhat.com> wrote:

> Most network drivers request their IRQ when the interface is activated.
> skge does it in ->probe() instead, because it can work with two-port
> cards where the two net_devices use the same IRQ. This works fine most
> of the time, except in some situations when the interface gets renamed.
> Consider this example:
> 
> 1. modprobe skge
>    The card is detected as eth0 and requests IRQ 17. Directory
>    /proc/irq/17/eth0 is created.
> 2. There is an udev rule which says this interface should be called
>    eth1, so udev renames eth0 -> eth1.
> 3. modprobe 8139too
>    The Realtek card is detected as eth0. It will be using IRQ 17 too.
> 4. ip link set eth0 up
>    Now 8139too requests IRQ 17.
> 
> The result is:
> WARNING: at fs/proc/generic.c:590 proc_register ...
> proc_dir_entry '17/eth0' already registered
> ...
> And "ls /proc/irq/17" shows two subdirectories, both called eth0.
> 
> Fix it by using a unique name for skge's IRQ, based on the PCI address.
> The naming from the example then looks like this:
> $ grep skge /proc/interrupts
>  17:        169   IO-APIC-fasteoi   skge@0000:00:0a.0, eth0
> 
> irqbalance daemon will have to be taught to recognize "skge@" as an
> Ethernet interrupt. This will be a one-liner addition in classify.c. I
> will send a patch to irqbalance if this change is accepted.
> 
> Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
> 
> Index: kernel/drivers/net/skge.c
> ===================================================================
> --- kernel.orig/drivers/net/skge.c
> +++ kernel/drivers/net/skge.c
> @@ -3895,6 +3895,7 @@ static int __devinit skge_probe(struct p
>  	struct net_device *dev, *dev1;
>  	struct skge_hw *hw;
>  	int err, using_dac = 0;
> +	size_t irq_name_len;
>  
>  	err = pci_enable_device(pdev);
>  	if (err) {
> @@ -3935,11 +3936,13 @@ static int __devinit skge_probe(struct p
>  #endif
>  
>  	err = -ENOMEM;
> -	hw = kzalloc(sizeof(*hw), GFP_KERNEL);
> +	irq_name_len = strlen(DRV_NAME) + strlen(dev_name(&pdev->dev)) + 2;
> +	hw = kzalloc(sizeof(*hw) + irq_name_len, GFP_KERNEL);
>  	if (!hw) {
>  		dev_err(&pdev->dev, "cannot allocate hardware struct\n");
>  		goto err_out_free_regions;
>  	}
> +	sprintf(hw->irq_name, DRV_NAME "@%s", dev_name(&pdev->dev));

I like this with one small change. Please use:
         skge@pci:0000:00:02.0
This makes the driver follow same format as existing DRM graphics drivers.
Michal could you follow up with additional patches for:
   1. sky2 driver has same issue
   2. irqbalance has a list of special drivers that needs to be updated


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Patch

Index: kernel/drivers/net/skge.c
===================================================================
--- kernel.orig/drivers/net/skge.c
+++ kernel/drivers/net/skge.c
@@ -3895,6 +3895,7 @@  static int __devinit skge_probe(struct p
 	struct net_device *dev, *dev1;
 	struct skge_hw *hw;
 	int err, using_dac = 0;
+	size_t irq_name_len;
 
 	err = pci_enable_device(pdev);
 	if (err) {
@@ -3935,11 +3936,13 @@  static int __devinit skge_probe(struct p
 #endif
 
 	err = -ENOMEM;
-	hw = kzalloc(sizeof(*hw), GFP_KERNEL);
+	irq_name_len = strlen(DRV_NAME) + strlen(dev_name(&pdev->dev)) + 2;
+	hw = kzalloc(sizeof(*hw) + irq_name_len, GFP_KERNEL);
 	if (!hw) {
 		dev_err(&pdev->dev, "cannot allocate hardware struct\n");
 		goto err_out_free_regions;
 	}
+	sprintf(hw->irq_name, DRV_NAME "@%s", dev_name(&pdev->dev));
 
 	hw->pdev = pdev;
 	spin_lock_init(&hw->hw_lock);
@@ -3974,7 +3977,7 @@  static int __devinit skge_probe(struct p
 		goto err_out_free_netdev;
 	}
 
-	err = request_irq(pdev->irq, skge_intr, IRQF_SHARED, dev->name, hw);
+	err = request_irq(pdev->irq, skge_intr, IRQF_SHARED, hw->irq_name, hw);
 	if (err) {
 		dev_err(&pdev->dev, "%s: cannot assign irq %d\n",
 		       dev->name, pdev->irq);
Index: kernel/drivers/net/skge.h
===================================================================
--- kernel.orig/drivers/net/skge.h
+++ kernel/drivers/net/skge.h
@@ -2423,6 +2423,8 @@  struct skge_hw {
 	u16		     phy_addr;
 	spinlock_t	     phy_lock;
 	struct tasklet_struct phy_task;
+
+	char		     irq_name[0]; /* name for /proc/interrupts */
 };
 
 enum pause_control {