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lws_sul: always iterate from head of list

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The sul callback is allowed to do anything to the sul list, it's
not possible to safely iterate it inbetween calls.

Luckily because it's sorted, we only ever care about the current
head, so switch to iterating it like that.
This commit is contained in:
Andy Green 2019-10-14 09:50:12 +01:00
parent 667f9d1fb3
commit 0ff633eb35
1 changed files with 18 additions and 19 deletions
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37
lib/core-net/sorted-usec-list.c
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@ -85,30 +85,29 @@ lws_sul_schedule(struct lws_context *context, int tsi,
lws_usec_t
__lws_sul_check(lws_dll2_owner_t *own, lws_usec_t usnow)
{
lws_usec_t future_us = 0;
while (lws_dll2_get_head(own)) {
lws_start_foreach_dll_safe(struct lws_dll2 *, p, tp,
lws_dll2_get_head(own)) {
/* .list is always first member in lws_sorted_usec_list_t */
lws_sorted_usec_list_t *sul = (lws_sorted_usec_list_t *)p;
lws_sorted_usec_list_t *sul = (lws_sorted_usec_list_t *)
lws_dll2_get_head(own);
assert(sul->us); /* shouldn't be on the list otherwise */
if (sul->us <= usnow) {
/* seq has timed out... remove him from timeout list */
lws_dll2_remove(&sul->list);
sul->us = 0;
sul->cb(sul);
} else {
/*
* No need to look further if we met one later than now:
* the list is sorted in ascending time order
*/
future_us = sul->us - usnow;
break;
}
if (sul->us > usnow)
return sul->us - usnow;
} lws_end_foreach_dll_safe(p, tp);
/* his moment has come... remove him from timeout list */
lws_dll2_remove(&sul->list);
sul->us = 0;
sul->cb(sul);
return future_us;
/*
* The callback may have done any mixture of delete
* and add sul entries... eg, close a wsi may pull out
* multiple entries making iterating it statefully
* unsafe. Always restart at the current head of list.
*/
}
return 0;
}