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devip: properly rlock() the routelock for v4lookup() and v6lookup()

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i'm not confident about mutating the route tree
pointers and have concurrent readers walking the
pointer chains.

given that most route lookups are bypassed now
for non-routing case and we are not building a
high performance router here, lets play it safe.
This commit is contained in:
cinap_lenrek 2021-10-10 14:27:08 +00:00
parent e687d25478
commit 365e63b36a
1 changed files with 30 additions and 29 deletions
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59
sys/src/9/ip/iproute.c
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@ -47,14 +47,10 @@ allocroute(int type)
l = &v6freelist; l = &v6freelist;
} }
r = *l; if((r = *l) != nil)
if(r != nil){
*l = r->mid; *l = r->mid;
} else { else
r = malloc(n); r = smalloc(n);
if(r == nil)
panic("out of routing nodes");
}
memset(r, 0, n); memset(r, 0, n);
r->type = type; r->type = type;
r->ifc = nil; r->ifc = nil;
@ -388,7 +384,7 @@ looknodetag(Route *r, char *tag)
static void static void
routeadd(Fs *f, Route *r) routeadd(Fs *f, Route *r)
{ {
Route **h, **e, *p; Route **h, **e, *p, *q;
if(r->type & Rv4){ if(r->type & Rv4){
h = &f->v4root[V4H(r->v4.address)]; h = &f->v4root[V4H(r->v4.address)];
@ -414,8 +410,9 @@ routeadd(Fs *f, Route *r)
addnode(f, h, p); addnode(f, h, p);
while((p = f->queue) != nil) { while((p = f->queue) != nil) {
f->queue = p->mid; f->queue = p->mid;
walkadd(f, h, p->left); q = p->left;
freeroute(p); freeroute(p);
walkadd(f, h, q);
} }
} }
@ -428,7 +425,7 @@ routeadd(Fs *f, Route *r)
static void static void
routerem(Fs *f, Route *r) routerem(Fs *f, Route *r)
{ {
Route **h, **e, **l, *p; Route **h, **e, **l, *p, *q;
if(r->type & Rv4){ if(r->type & Rv4){
h = &f->v4root[V4H(r->v4.address)]; h = &f->v4root[V4H(r->v4.address)];
@ -452,8 +449,9 @@ routerem(Fs *f, Route *r)
while((p = f->queue) != nil) { while((p = f->queue) != nil) {
f->queue = p->mid; f->queue = p->mid;
walkadd(f, h, p->left); q = p->left;
freeroute(p); freeroute(p);
walkadd(f, h, q);
} }
} }
@ -605,9 +603,11 @@ v4lookup(Fs *f, uchar *a, uchar *s, Routehint *rh)
&& q->ref > 0) && q->ref > 0)
return q; return q;
q = nil;
la = nhgetl(a); la = nhgetl(a);
ls = nhgetl(s); ls = nhgetl(s);
q = nil;
rlock(&routelock);
for(p = f->v4root[V4H(la)]; p != nil;){ for(p = f->v4root[V4H(la)]; p != nil;){
if(la < p->v4.address){ if(la < p->v4.address){
p = p->left; p = p->left;
@ -630,15 +630,15 @@ v4lookup(Fs *f, uchar *a, uchar *s, Routehint *rh)
q = p; q = p;
p = p->mid; p = p->mid;
} }
if(q != nil){
if(q == nil || q->ref == 0 || routefindipifc(q, f) == nil) if(routefindipifc(q, f) == nil)
return nil; q = nil;
else if(rh != nil){
if(rh != nil){ rh->r = q;
rh->r = q; rh->rgen = v4routegeneration;
rh->rgen = v4routegeneration; }
} }
runlock(&routelock);
return q; return q;
} }
@ -665,12 +665,13 @@ v6lookup(Fs *f, uchar *a, uchar *s, Routehint *rh)
&& q->ref > 0) && q->ref > 0)
return q; return q;
q = nil;
for(h = 0; h < IPllen; h++){ for(h = 0; h < IPllen; h++){
la[h] = nhgetl(a+4*h); la[h] = nhgetl(a+4*h);
ls[h] = nhgetl(s+4*h); ls[h] = nhgetl(s+4*h);
} }
q = nil; rlock(&routelock);
for(p = f->v6root[V6H(la)]; p != nil;){ for(p = f->v6root[V6H(la)]; p != nil;){
for(h = 0; h < IPllen; h++){ for(h = 0; h < IPllen; h++){
x = la[h]; x = la[h];
@ -722,15 +723,15 @@ v6lookup(Fs *f, uchar *a, uchar *s, Routehint *rh)
p = p->mid; p = p->mid;
next: ; next: ;
} }
if(q != nil){
if(q == nil || q->ref == 0 || routefindipifc(q, f) == nil) if(routefindipifc(q, f) == nil)
return nil; q = nil;
else if(rh != nil){
if(rh != nil){ rh->r = q;
rh->r = q; rh->rgen = v6routegeneration;
rh->rgen = v6routegeneration; }
} }
runlock(&routelock);
return q; return q;
} }