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devip: sanity check Nchan in Fsproto()

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devip can only handle Maskconv+1 conversations per
protocol depending on how many bits it uses in the
qid to encode the conversation number.

we check this when the protocol gets registered.

if we do not do this, the kernel will mysteriously
panic when the conversaion numbers collide which
took some time to debug.
This commit is contained in:
cinap_lenrek 2014-09-21 19:24:38 +02:00
parent 59ab557f31
commit 84c40fb226
1 changed files with 4 additions and 0 deletions
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4
sys/src/9/ip/devip.c
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@ -1243,6 +1243,10 @@ Fsproto(Fs *f, Proto *p)
p->qid.type = QTDIR; p->qid.type = QTDIR;
p->qid.path = QID(f->np, 0, Qprotodir); p->qid.path = QID(f->np, 0, Qprotodir);
if(p->nc > Maskconv+1){
print("Fsproto: %s nc %d > %d\n", p->name, p->nc, Maskconv+1);
p->nc = Maskconv+1;
}
p->conv = malloc(sizeof(Conv*)*(p->nc+1)); p->conv = malloc(sizeof(Conv*)*(p->nc+1));
if(p->conv == nil) if(p->conv == nil)
panic("Fsproto"); panic("Fsproto");