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re: rbuf starvation in the iwn driver

   On Sat, Apr 10, 2010 at 12:49:48PM +1000, matthew green wrote:
   > would you try this variant?  it handles the case where MEXTMALLOC()
   > would fail to allocate external storage, and seems to work on my 
   > iwn(4).  i'll commit this if you confirm it works.
   Is there any reason not to replace the implementation of
   iwn_alloc_rbuf() with MEXTMALLOC(), instead?

as in hide this inside iwn_alloc_rbuf()?  probably.  or do you
mean give up the private buffer collection?  in that case, i
am not sure what the right solution would be, seems like a
concept we want to decide for (all?) network drivers...
   Previously, a remote host could exhaust an iwn(4)'s private Rx buffer
   pool by, say, sending a ton of tiny segments to TCP sockets that already
   have a long backlog.  Can a remote host now deplete the malloc(9) pool
   in the same way?

i don't know.  however, i'd trade that potential DoS for the
actual much better working driver now... :)

still, this is something worth investigating (but not enough
for me to look at any time soon.)


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