Messages in this thread | | | Date | Sat, 12 Jul 2008 14:59:44 +0200 (CEST) | From | Stefan Richter <> | Subject | Re: [patch 1/4] firewire: fix race of bus reset with request transmission |
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I wrote: > Contexts which access an instance of struct fw_transaction are: > 1. the submitter, until it inserted the packet which is embedded in the > transaction into the AT req DMA, > 2. the AsReqTrContext tasklet when the request packet was acked by the > responder node or transmission to the responder failed, > 3. the AsRspRcvContext tasklet when it found a request which matched > an incoming response, > 4. the card->flush_timer when it picks up timed-out transactions to > cancel them, > 5. the bus reset tasklet when it cancels transactions (this access is > eliminated by this patch), > 6. a process which shuts down an fw_card (unregisters it from fw-core > when the controller is unbound from fw-ohci) --- although in this > case there shouldn't really be any transactions anymore because we > wait until all card users finished their business with the card. > > All of these contexts run concurrently (except for the 6th, presumably).
PS: Actually the three tasklets (2nd, 3rd, 5th context) are all scheduled on the same CPU, hence are serialized. Therefore
> The 5th looks safe against 2nd, 3rd [...] but is unsafe against 1st.
5th is serialized against 4th and 6th by lock protection of card->transaction_list accesses. -- Stefan Richter -=====-==--- -=== -==-- http://arcgraph.de/sr/
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