cvs commit: src/sys/net80211 ieee80211_ioctl.c

[Jung-uk Kim]

On Thursday 03 March 2005 12:35 pm, Bill Paul wrote:
> wpaul       2005-03-03 17:35:05 UTC
>
>   FreeBSD src repository
>
>   Modified files:
>     sys/net80211         ieee80211_ioctl.c
>   Log:
>   Recently, it was reported to me that you could provoke a double
> fault panic with the NDISulator if you did "ifconfig ndis0
> 10.0.0.1/24," whereas "ifconfig ndis0 10.0.0.1/24 up" worked fine.
> The double fault was caused by the ifconfig thread running out of
> kernel stack space. (This was partly due to the NDIsulator using a
> couple of big buffers on the stack, but even after fixing that the
> double fault persisted.)
>
>   It turns out that ndis_init() is called in both cases, but in the
> first case the code path passes through ieee80211_ioctl(), and it
> turns out ieee80211_ioctl() consumes a whopping 2400 bytes of stack
> space. Apparently, gcc -O2 causes the ieee80211_ioctl_get80211()
> routine to be inlined into ieee80211_ioctl(), and for some reason
> which I do not fully understand, this causes ieee80211_ioctl() to
> consume an extra 2K of stack space.
>
>   To prevent this overly agressive optimization,
> ieee80211_ioctl_get80211() is now declared with __attribute__
> ((noinline)). With this change, ieee80211_ioctl() now only reserves
> about 200 bytes of stack instead of 2400.
>
>   Revision  Changes    Path
>   1.19      +19 -0     src/sys/net80211/ieee80211_ioctl.c

Check this commit:
http://docs.freebsd.org/cgi/mid.cgi?200503022133.j22LXTih011115

and this comment:
http://docs.freebsd.org/cgi/mid.cgi?20050303161436.0cczcopocg84g4ks

Thanks,

Jung-uk Kim