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Clean up dead code in hsh_deref_objhead_unlock

req's on waiting list do indeed hold an objhead ref (req->hash_objhead),
so the condition for the while loop in hsh_deref_objhead_unlock will
always evaluate to false.

This gets rid of the needless rushing code and replaces it with an
assert.
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daghf committed Dec 5, 2018
1 parent b637c11 commit b81bb71db0ce1655a0a23bdb47e5b8b3f8315749
Showing with 8 additions and 18 deletions.
  1. +8 −18 bin/varnishd/cache/cache_hash.c
@@ -773,8 +773,10 @@ HSH_Unbusy(struct worker *wrk, struct objcore *oc)
VTAILQ_REMOVE(&oh->objcs, oc, hsh_list);
VTAILQ_INSERT_HEAD(&oh->objcs, oc, hsh_list);
oc->flags &= ~OC_F_BUSY;
if (!VTAILQ_EMPTY(&oh->waitinglist))
if (!VTAILQ_EMPTY(&oh->waitinglist)) {
assert(oh->refcnt > 1);
hsh_rush1(wrk, oh, &rush, HSH_RUSH_POLICY);
}
Lck_Unlock(&oh->mtx);
if (!(oc->flags & OC_F_PRIVATE))
EXP_Insert(wrk, oc);
@@ -929,8 +931,10 @@ HSH_DerefObjCore(struct worker *wrk, struct objcore **ocp, int rushmax)
r = --oc->refcnt;
if (!r)
VTAILQ_REMOVE(&oh->objcs, oc, hsh_list);
if (!VTAILQ_EMPTY(&oh->waitinglist))
if (!VTAILQ_EMPTY(&oh->waitinglist)) {
assert(oh->refcnt > 1);
hsh_rush1(wrk, oh, &rush, rushmax);
}
Lck_Unlock(&oh->mtx);
hsh_rush2(wrk, &rush);
if (r != 0)
@@ -955,11 +959,9 @@ static int
hsh_deref_objhead_unlock(struct worker *wrk, struct objhead **poh)
{
struct objhead *oh;
struct rush rush;
CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
TAKE_OBJ_NOTNULL(oh, poh, OBJHEAD_MAGIC);
INIT_OBJ(&rush, RUSH_MAGIC);
Lck_AssertHeld(&oh->mtx);
@@ -971,20 +973,8 @@ hsh_deref_objhead_unlock(struct worker *wrk, struct objhead **poh)
return(1);
}
/*
* Make absolutely certain that we do not let the final ref
* disappear until the waitinglist is empty.
* This is necessary because the req's on the waiting list do
* not hold any ref on the objhead of their own, and we cannot
* just make the hold the same ref's as objcore, that would
* confuse hashers.
*/
while (oh->refcnt == 1 && !VTAILQ_EMPTY(&oh->waitinglist)) {
hsh_rush1(wrk, oh, &rush, HSH_RUSH_ALL);
Lck_Unlock(&oh->mtx);
hsh_rush2(wrk, &rush);
Lck_Lock(&oh->mtx);
}
if (oh->refcnt == 1)
assert(VTAILQ_EMPTY(&oh->waitinglist));
assert(oh->refcnt > 0);
return (hash->deref(wrk, oh));

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