Re: firmware_loading_store: vmap() failed, broken firmware with kernles .27 - .30

[Golden <goldenstranger@yahoo.com>]

> I was able to reproduce "unexpected value" with Linux
> 2.6.28.10 and
> ar9170usb.
> 
> After adding some debug printk's, I get this:
> 
> firmware_loading_store: loading = 1
> firmware_loading_store: loading = 1
> firmware_loading_store: loading = 0
> fw_priv->fw->data = ffffc2001027a000
> firmware_loading_store: loading = 0
> compat_firmware 1-7: firmware_loading_store: unexpected
> value (0)
> firmware_loading_store: abort
> usb 1-7: ar9170.fw firmware file not found, trying old
> firmware...
> 
> It looks like we have a race condition here.  Two
> processes try to load
> the firmware.
> 
> I remember vaguely that it was discussed before. 
> Google search for
> "firmware_loading_store race" finds some interesting links,
> but I cannot
> find a fix.  Likewise, search for
> "firmware_loading_store: unexpected
> value" finds a lot of stuff in the Linux 2.6.13 timeframe.
> 
> It looks like a race condition.  Adding dump_stack()
> to the beginning of
> firmware_loading_store() makes the problem disappear.
> 
> -- 
> Regards,
> Pavel Roskin



Hi, Pavel,

This appears to be an important bug fix for a variety of users with older kernels. Can you prepare proper patch for this and did you have a chance to test if these amendments cause trouble with newer kernels? 

Regards.