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Revert "varlink: avoid using dangling ref in varlink_close_unref()"

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This reverts commit 39ad3f1c09.
This commit is contained in:
Lennart Poettering
2021-05-11 21:45:32 +02:00
parent 5c2e595767
commit cc6b0a18ff
1 changed files with 6 additions and 24 deletions
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src/shared/varlink.c
+6 -24
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@@ -1210,9 +1210,8 @@ int varlink_close(Varlink *v) {
varlink_set_state(v, VARLINK_DISCONNECTED);
/* Let's take a reference first, since varlink_detach_server() might drop the final ref from the
* disconnect callback, which would invalidate the pointer we are holding before we can call
* varlink_clear(). */
/* Let's take a reference first, since varlink_detach_server() might drop the final (dangling) ref
* which would destroy us before we can call varlink_clear() */
varlink_ref(v);
varlink_detach_server(v);
varlink_clear(v);
@@ -1225,32 +1224,15 @@ Varlink* varlink_close_unref(Varlink *v) {
if (!v)
return NULL;
/* A reference is given to us to be destroyed. But when calling varlink_close(), a callback might
* also drop a reference. We allow this, and will hold a temporary reference to the object to make
* sure that the object still exists when control returns to us. If there's just one reference
* remaining after varlink_close(), even though there were at least two right before, we'll handle
* that gracefully instead of crashing.
*
* In other words, this call drops the donated reference, but if the internal call to varlink_close()
* dropped a reference to, we don't drop the reference afain. This allows the caller to say:
* global_object->varlink = varlink_close_unref(global_object->varlink);
* even though there is some callback which has access to global_object and may drop the reference
* stored in global_object->varlink. Without this step, the same code would have to be written as:
* Varlink *t = TAKE_PTR(global_object->varlink);
* varlink_close_unref(t);
*/
/* n_ref >= 1 */
varlink_ref(v); /* n_ref >= 2 */
varlink_close(v); /* n_ref >= 1 */
if (v->n_ref > 1)
v->n_ref--; /* n_ref >= 1 */
(void) varlink_close(v);
return varlink_unref(v);
}
Varlink* varlink_flush_close_unref(Varlink *v) {
if (v)
varlink_flush(v);
if (!v)
return NULL;
(void) varlink_flush(v);
return varlink_close_unref(v);
}