cvs commit: src/sys/net80211 ieee80211_ioctl.c

[Bill Paul]

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