Re: [RFC] net: napi fix

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Stephen Hemminger wrote:
On Thu, 13 Dec 2007 06:19:38 -0800 (PST)
David Miller <[email protected]> wrote:

From: Andrew Gallatin <[email protected]>
Date: Thu, 13 Dec 2007 09:13:54 -0500

If the netif_running() check is indeed required to make a device break
out of napi polling and respond to an ifconfig down, then I think the
netif_running() check should be moved up into net_rx_action() to avoid
potential for driver complexity and bugs like the ones you found.
That, or something like it, definitely sounds reasonable and much
better than putting the check into every driver :-)
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

It is not possible to do netif_running() check in generic code as currently
written because of the case of devices where a single NAPI object is
being used to handle two devices. The association between napi and netdevice
is M to N.  There are cases like niu that have multiple NAPI's and one
netdevice; and devices like sky2 that can have one NAPI and 2 netdevice's.

Ah, now I see.  I forgot that not every device has a 1:1::napi:netdev
relationship.

Could we make an optional *dev_state field in the napi structure.
It would be initialized to __LINK_STATE_START.  Devices which have
a 1:1 NAPI:netdevice relationship would set it to &netdev->state.
The generic code would then do a test_bit(__LINK_STATE_START, napi->dev_state), and 1:1 drivers could remove this check.
M:N drivers would pay for a useless (to them) test_bit, and would
have to provide their own netif_running check to get termination
under heavy load.

Just an idea, perhaps there is a better way which is less hacky.

Or perhaps we should just leave things as is.

Drew
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux