Messages in this thread | | | Date | Tue, 7 Jan 2014 14:50:59 +0000 | From | Zoltan Kiss <> | Subject | Re: [PATCH net-next v2 1/9] xen-netback: Introduce TX grant map definitions |
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On 16/12/13 17:50, Wei Liu wrote: > On Mon, Dec 16, 2013 at 03:21:40PM +0000, Zoltan Kiss wrote: > [...] >>>>>>> >>>>>>> Should this be BUG_ON? AIUI this kthread should be the only one doing >>>>>>> unmap, right? >>>>> The NAPI instance can do it as well if it is a small packet fits >>>>> into PKT_PROT_LEN. But still this scenario shouldn't really happen, >>>>> I was just not sure we have to crash immediately. Maybe handle it as >>>>> a fatal error and destroy the vif? >>>>> >>> It depends. If this is within the trust boundary, i.e. everything at the >>> stage should have been sanitized then we should BUG_ON because there's >>> clearly a bug somewhere in the sanitization process, or in the >>> interaction of various backend routines. >> >> My understanding is that crashing should be avoided if we can bail >> out somehow. At this point there is clearly a bug in netback >> somewhere, something unmapped that page before it should have >> happened, or at least that array get corrupted somehow. However >> there is a chance that xenvif_fatal_tx_err() can contain the issue, >> and the rest of the system can go unaffected. >> > > That would make debugging much harder if a crash is caused by a previous > corrupted array and we pretend we can carry on serving IMHO. Now netback > is having three routines (NAPI, two kthreads) to serve a single vif, the > interation among them makes bug hard to reproduce.
OK, I'll make this a BUG() in the next series.
Zoli
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