Re: [Kgdb-bugreport] [PATCH] 8139too: harden against TX ring overflow
Status: Beta
Brought to you by:
jwessel
From: Sergei S. <ssh...@ru...> - 2007-05-24 21:42:57
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Jeff Garzik wrote: >>> This driver's 4-packet deep TX queue is too sensible to the >>> "careless" callers >>> ignoring its state (like netpoll in trapped mode), so add "queue >>> full" check at >>> the start of the hard_start_xmit() method (only under #ifndef >>> RTL8139_NDEBUG, >>> otherwise the queue will get stuck once dirty pointer gets out of >>> sync); switch >>> to using appropriate mnemonics for the return values while at it. >>> Also, the out-of-sync dirty pointer check is misplaced in >>> rtl8139_tx_interrupt() >>> which causes TX descriptors to be inspected more than once in case >>> the pointer >>> really gets out-of-sync (and incrementing the dirty pointer always by >>> 4 is just >>> not enough, e.g. KGDBoE managed to stuff 20+ extra buffers into the >>> queue) -- >>> place it before the loop and limit the loop to only look through 4 >>> descriptors >>> at most, so that already overwritten descriptors are just not counted. >>> Signed-off-by: Sergei Shtylyov <ssh...@ru...> >> Jeff, do you have any opinion on this patch? > The out-of-sync dirty pointer check is leftover boilerplate, and not > really indicative of anything except for some code to be removed. > As for the other stuff, I would say "fix the caller". We don't need to > hack every driver for cases where netpoll is being dumb. Caller's been fixed now. So, I read that as reject. :-) > Jeff WBR, Sergei |