return true;
}
+enum unix_recv_queue_lock_class {
+ U_RECVQ_LOCK_NORMAL,
+ U_RECVQ_LOCK_EMBRYO,
+};
+
+static void unix_collect_skb(struct list_head *scc, struct sk_buff_head *hitlist)
+{
+ struct unix_vertex *vertex;
+
+ list_for_each_entry_reverse(vertex, scc, scc_entry) {
+ struct sk_buff_head *queue;
+ struct unix_edge *edge;
+ struct unix_sock *u;
+
+ edge = list_first_entry(&vertex->edges, typeof(*edge), vertex_entry);
+ u = edge->predecessor;
+ queue = &u->sk.sk_receive_queue;
+
+ spin_lock(&queue->lock);
+
+ if (u->sk.sk_state == TCP_LISTEN) {
+ struct sk_buff *skb;
+
+ skb_queue_walk(queue, skb) {
+ struct sk_buff_head *embryo_queue = &skb->sk->sk_receive_queue;
+
+ /* listener -> embryo order, the inversion never happens. */
+ spin_lock_nested(&embryo_queue->lock, U_RECVQ_LOCK_EMBRYO);
+ skb_queue_splice_init(embryo_queue, hitlist);
+ spin_unlock(&embryo_queue->lock);
+ }
+ } else {
+ skb_queue_splice_init(queue, hitlist);
+
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+ if (u->oob_skb) {
+ kfree_skb(u->oob_skb);
+ u->oob_skb = NULL;
+ }
+#endif
+ }
+
+ spin_unlock(&queue->lock);
+ }
+}
+
static bool unix_scc_cyclic(struct list_head *scc)
{
struct unix_vertex *vertex;
static LIST_HEAD(unix_visited_vertices);
static unsigned long unix_vertex_grouped_index = UNIX_VERTEX_INDEX_MARK2;
-static void __unix_walk_scc(struct unix_vertex *vertex, unsigned long *last_index)
+static void __unix_walk_scc(struct unix_vertex *vertex, unsigned long *last_index,
+ struct sk_buff_head *hitlist)
{
LIST_HEAD(vertex_stack);
struct unix_edge *edge;
scc_dead = unix_vertex_dead(vertex);
}
- if (!unix_graph_maybe_cyclic)
+ if (scc_dead)
+ unix_collect_skb(&scc, hitlist);
+ else if (!unix_graph_maybe_cyclic)
unix_graph_maybe_cyclic = unix_scc_cyclic(&scc);
list_del(&scc);
goto prev_vertex;
}
-static void unix_walk_scc(void)
+static void unix_walk_scc(struct sk_buff_head *hitlist)
{
unsigned long last_index = UNIX_VERTEX_INDEX_START;
struct unix_vertex *vertex;
vertex = list_first_entry(&unix_unvisited_vertices, typeof(*vertex), entry);
- __unix_walk_scc(vertex, &last_index);
+ __unix_walk_scc(vertex, &last_index, hitlist);
}
list_replace_init(&unix_visited_vertices, &unix_unvisited_vertices);
unix_graph_grouped = true;
}
-static void unix_walk_scc_fast(void)
+static void unix_walk_scc_fast(struct sk_buff_head *hitlist)
{
while (!list_empty(&unix_unvisited_vertices)) {
struct unix_vertex *vertex;
scc_dead = unix_vertex_dead(vertex);
}
+ if (scc_dead)
+ unix_collect_skb(&scc, hitlist);
+
list_del(&scc);
}
list_replace_init(&unix_visited_vertices, &unix_unvisited_vertices);
}
-static LIST_HEAD(gc_candidates);
-static LIST_HEAD(gc_inflight_list);
-
-/* Keep the number of times in flight count for the file
- * descriptor if it is for an AF_UNIX socket.
- */
-void unix_inflight(struct user_struct *user, struct file *filp)
-{
- struct unix_sock *u = unix_get_socket(filp);
-
- spin_lock(&unix_gc_lock);
-
- if (u) {
- if (!u->inflight) {
- WARN_ON_ONCE(!list_empty(&u->link));
- list_add_tail(&u->link, &gc_inflight_list);
- } else {
- WARN_ON_ONCE(list_empty(&u->link));
- }
- u->inflight++;
- }
-
- spin_unlock(&unix_gc_lock);
-}
-
-void unix_notinflight(struct user_struct *user, struct file *filp)
-{
- struct unix_sock *u = unix_get_socket(filp);
-
- spin_lock(&unix_gc_lock);
-
- if (u) {
- WARN_ON_ONCE(!u->inflight);
- WARN_ON_ONCE(list_empty(&u->link));
-
- u->inflight--;
- if (!u->inflight)
- list_del_init(&u->link);
- }
-
- spin_unlock(&unix_gc_lock);
-}
-
-static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),
- struct sk_buff_head *hitlist)
-{
- struct sk_buff *skb;
- struct sk_buff *next;
-
- spin_lock(&x->sk_receive_queue.lock);
- skb_queue_walk_safe(&x->sk_receive_queue, skb, next) {
- /* Do we have file descriptors ? */
- if (UNIXCB(skb).fp) {
- bool hit = false;
- /* Process the descriptors of this socket */
- int nfd = UNIXCB(skb).fp->count;
- struct file **fp = UNIXCB(skb).fp->fp;
-
- while (nfd--) {
- /* Get the socket the fd matches if it indeed does so */
- struct unix_sock *u = unix_get_socket(*fp++);
-
- /* Ignore non-candidates, they could have been added
- * to the queues after starting the garbage collection
- */
- if (u && test_bit(UNIX_GC_CANDIDATE, &u->gc_flags)) {
- hit = true;
-
- func(u);
- }
- }
- if (hit && hitlist != NULL) {
- __skb_unlink(skb, &x->sk_receive_queue);
- __skb_queue_tail(hitlist, skb);
- }
- }
- }
- spin_unlock(&x->sk_receive_queue.lock);
-}
-
-static void scan_children(struct sock *x, void (*func)(struct unix_sock *),
- struct sk_buff_head *hitlist)
-{
- if (x->sk_state != TCP_LISTEN) {
- scan_inflight(x, func, hitlist);
- } else {
- struct sk_buff *skb;
- struct sk_buff *next;
- struct unix_sock *u;
- LIST_HEAD(embryos);
-
- /* For a listening socket collect the queued embryos
- * and perform a scan on them as well.
- */
- spin_lock(&x->sk_receive_queue.lock);
- skb_queue_walk_safe(&x->sk_receive_queue, skb, next) {
- u = unix_sk(skb->sk);
-
- /* An embryo cannot be in-flight, so it's safe
- * to use the list link.
- */
- WARN_ON_ONCE(!list_empty(&u->link));
- list_add_tail(&u->link, &embryos);
- }
- spin_unlock(&x->sk_receive_queue.lock);
-
- while (!list_empty(&embryos)) {
- u = list_entry(embryos.next, struct unix_sock, link);
- scan_inflight(&u->sk, func, hitlist);
- list_del_init(&u->link);
- }
- }
-}
-
-static void dec_inflight(struct unix_sock *usk)
-{
- usk->inflight--;
-}
-
-static void inc_inflight(struct unix_sock *usk)
-{
- usk->inflight++;
-}
-
-static void inc_inflight_move_tail(struct unix_sock *u)
-{
- u->inflight++;
-
- /* If this still might be part of a cycle, move it to the end
- * of the list, so that it's checked even if it was already
- * passed over
- */
- if (test_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags))
- list_move_tail(&u->link, &gc_candidates);
-}
-
static bool gc_in_progress;
static void __unix_gc(struct work_struct *work)
{
struct sk_buff_head hitlist;
- struct unix_sock *u, *next;
- LIST_HEAD(not_cycle_list);
- struct list_head cursor;
spin_lock(&unix_gc_lock);
- if (!unix_graph_maybe_cyclic)
+ if (!unix_graph_maybe_cyclic) {
+ spin_unlock(&unix_gc_lock);
goto skip_gc;
-
- if (unix_graph_grouped)
- unix_walk_scc_fast();
- else
- unix_walk_scc();
-
- /* First, select candidates for garbage collection. Only
- * in-flight sockets are considered, and from those only ones
- * which don't have any external reference.
- *
- * Holding unix_gc_lock will protect these candidates from
- * being detached, and hence from gaining an external
- * reference. Since there are no possible receivers, all
- * buffers currently on the candidates' queues stay there
- * during the garbage collection.
- *
- * We also know that no new candidate can be added onto the
- * receive queues. Other, non candidate sockets _can_ be
- * added to queue, so we must make sure only to touch
- * candidates.
- */
- list_for_each_entry_safe(u, next, &gc_inflight_list, link) {
- long total_refs;
-
- total_refs = file_count(u->sk.sk_socket->file);
-
- WARN_ON_ONCE(!u->inflight);
- WARN_ON_ONCE(total_refs < u->inflight);
- if (total_refs == u->inflight) {
- list_move_tail(&u->link, &gc_candidates);
- __set_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
- __set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
- }
- }
-
- /* Now remove all internal in-flight reference to children of
- * the candidates.
- */
- list_for_each_entry(u, &gc_candidates, link)
- scan_children(&u->sk, dec_inflight, NULL);
-
- /* Restore the references for children of all candidates,
- * which have remaining references. Do this recursively, so
- * only those remain, which form cyclic references.
- *
- * Use a "cursor" link, to make the list traversal safe, even
- * though elements might be moved about.
- */
- list_add(&cursor, &gc_candidates);
- while (cursor.next != &gc_candidates) {
- u = list_entry(cursor.next, struct unix_sock, link);
-
- /* Move cursor to after the current position. */
- list_move(&cursor, &u->link);
-
- if (u->inflight) {
- list_move_tail(&u->link, ¬_cycle_list);
- __clear_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
- scan_children(&u->sk, inc_inflight_move_tail, NULL);
- }
}
- list_del(&cursor);
- /* Now gc_candidates contains only garbage. Restore original
- * inflight counters for these as well, and remove the skbuffs
- * which are creating the cycle(s).
- */
- skb_queue_head_init(&hitlist);
- list_for_each_entry(u, &gc_candidates, link) {
- scan_children(&u->sk, inc_inflight, &hitlist);
+ __skb_queue_head_init(&hitlist);
-#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
- if (u->oob_skb) {
- kfree_skb(u->oob_skb);
- u->oob_skb = NULL;
- }
-#endif
- }
-
- /* not_cycle_list contains those sockets which do not make up a
- * cycle. Restore these to the inflight list.
- */
- while (!list_empty(¬_cycle_list)) {
- u = list_entry(not_cycle_list.next, struct unix_sock, link);
- __clear_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
- list_move_tail(&u->link, &gc_inflight_list);
- }
+ if (unix_graph_grouped)
+ unix_walk_scc_fast(&hitlist);
+ else
+ unix_walk_scc(&hitlist);
spin_unlock(&unix_gc_lock);
- /* Here we are. Hitlist is filled. Die. */
__skb_queue_purge(&hitlist);
-
- spin_lock(&unix_gc_lock);
-
- /* All candidates should have been detached by now. */
- WARN_ON_ONCE(!list_empty(&gc_candidates));
skip_gc:
- /* Paired with READ_ONCE() in wait_for_unix_gc(). */
WRITE_ONCE(gc_in_progress, false);
-
- spin_unlock(&unix_gc_lock);
}
static DECLARE_WORK(unix_gc_work, __unix_gc);
projects / linux.git / commitdiff