Avoiding an infinite loop in e1000 82575

[Adrian Chadd]

Heh, your solution isn't correct. There's a higher level race
condition somewhere.. :(

-a

On 6 December 2013 14:54, Karim Fodil-Lemelin
<fodillemlinkarim at gmail.com> wrote:
> Hi,
>
> I have encountered a strange issue were the igb driver goes into an infinite
> loop (I'm using version - 2.3.10) if many incantations of ifconfig are
> running in a while loop very fast. The following patch fixed it for me:
>
> @@ -1052,12 +1052,11 @@ static void e1000_release_swfw_sync_82575(struct
> e1000_hw *hw, u16 mask)
>  {
>         u32 swfw_sync;
>
>         DEBUGFUNC("e1000_release_swfw_sync_82575");
>
> -       while (e1000_get_hw_semaphore_generic(hw) != E1000_SUCCESS)
> -               ; /* Empty */
> +       e1000_get_hw_semaphore_generic(hw);
>
>         swfw_sync = E1000_READ_REG(hw, E1000_SW_FW_SYNC);
>         swfw_sync &= ~mask;
>         E1000_WRITE_REG(hw, E1000_SW_FW_SYNC, swfw_sync);
>
> Now, I haven't seen any side effect of this change except that it fixed my
> issue although I wonder what they are and what effect will this change have
> on the system?
>
> Thanks,
>
> Karim.
>
> PS: Some more information on the devices:
>
> dmesg:
>
> igb0: <Intel(R) PRO/1000 Network Connection version - 2.3.10> port
> 0xc880-0xc89f mem 0xfba80000-0xfbafffff,0xfbb78000-0xfbb7bfff irq 16 at
> device 0.0 on pci4
> igb0: Using MSIX interrupts with 2 vectors
> igb0: Ethernet address: 00:90:0b:2f:b8:00
> igb0: [ITHREAD]
> igb0: [ITHREAD]
> igb1: <Intel(R) PRO/1000 Network Connection version - 2.3.10> port
> 0xcc00-0xcc1f mem 0xfbb80000-0xfbbfffff,0xfbb7c000-0xfbb7ffff irq 17 at
> device 0.1 on pci4
> igb1: Using MSIX interrupts with 2 vectors
> igb1: Ethernet address: 00:90:0b:2f:b8:01
> igb1: [ITHREAD]
> igb1: [ITHREAD]
> igb2: <Intel(R) PRO/1000 Network Connection version - 2.3.10> port
> 0xd880-0xd89f mem 0xfbc80000-0xfbcfffff,0xfbd78000-0xfbd7bfff irq 16 at
> device 0.0 on pci5
> igb2: Using MSIX interrupts with 2 vectors
> igb2: Ethernet address: 00:90:0b:2f:b8:02
> igb2: [ITHREAD]
> igb2: [ITHREAD]
> igb3: <Intel(R) PRO/1000 Network Connection version - 2.3.10> port
> 0xdc00-0xdc1f mem 0xfbd80000-0xfbdfffff,0xfbd7c000-0xfbd7ffff irq 17 at
> device 0.1 on pci5
> igb3: Using MSIX interrupts with 2 vectors
> igb3: Ethernet address: 00:90:0b:2f:b8:03
> igb3: [ITHREAD]
> igb3: [ITHREAD]
>
> pciconf
>
> igb0 at pci0:4:0:0:        class=0x020000 card=0x00008086 chip=0x150e8086
> rev=0x01 hdr=0x00
> igb1 at pci0:4:0:1:        class=0x020000 card=0x00008086 chip=0x150e8086
> rev=0x01 hdr=0x00
> igb2 at pci0:5:0:0:        class=0x020000 card=0x00008086 chip=0x150e8086
> rev=0x01 hdr=0x00
> igb3 at pci0:5:0:1:        class=0x020000 card=0x00008086 chip=0x150e8086
> rev=0x01 hdr=0x00
>
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