[Bug 432636] Re: Karmic linux-2.6.31-10-generic (and later) breaks hostap

[koshimazaki]

I confirm as well, tested today on 2.6.31-21-generic (karmic-proposed)
and 2.6.31-20. I tried the proposed kernel because it contains a fix for
another hostap-related bug, #444801, but it seems unrelated to this bug.

Specifically, my log contains all the messages mentioned by Geoffrey
Hausheer in post #2 (apart from hostap_pci: 'hardware initialization
failed') and I also get lots of 'wifi0: Interrupt, but dev not
configured' lines.

After some searching, I found a possible clue in the changelog for 2.6.31-10, https://launchpad.net/ubuntu/+source/linux/2.6.31-10.30 . It says:
* SAUCE: wireless: hostap, fix oops due to early probing interrupt
The diff for that version (available from the above mentioned page) reveals that the following was added to hostap_hw.c:

+       /* Detect early interrupt before driver is fully configued */
+       if (!dev->base_addr) {
+               if (net_ratelimit()) {
+                       printk(KERN_DEBUG "%s: Interrupt, but dev not configured\n",
+                              dev->name);
+               }
+               return IRQ_HANDLED;
+       }
+

Note the printk message. Apparently the code was added to fix bug #254837. This fix was introduced in 2.6.31-10.30 and 2.6.28-15.52 which seems consistent with Geoffrey's report about these being the versions where hostap broke.
I suspect that this fix is what broke hostap for us and I'm tempted to build a kernel with these lines removed. I realise they where put there for a reason but I've used the hostap driver with Prism 2.5 successfully in the past, before they were introduced, and I can't use it now.

Note that I am not at all familiar with the linux or ubuntu kernel
development and only have a vague idea of what I'm talking about so
excuse me if it's all wrong, or obvious.

-- 
Karmic linux-2.6.31-10-generic (and later) breaks hostap
https://bugs.launchpad.net/bugs/432636
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