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Diffstat (limited to 'net/unix/garbage.c')
-rw-r--r--net/unix/garbage.c62
1 files changed, 47 insertions, 15 deletions
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 2a27b84f740b..abb3ab34cb1e 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -80,6 +80,7 @@
#include <linux/file.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
+#include <linux/wait.h>
#include <net/sock.h>
#include <net/af_unix.h>
@@ -91,6 +92,7 @@
static LIST_HEAD(gc_inflight_list);
static LIST_HEAD(gc_candidates);
static DEFINE_SPINLOCK(unix_gc_lock);
+static DECLARE_WAIT_QUEUE_HEAD(unix_gc_wait);
unsigned int unix_tot_inflight;
@@ -186,8 +188,17 @@ static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),
*/
struct sock *sk = unix_get_socket(*fp++);
if (sk) {
- hit = true;
- func(unix_sk(sk));
+ struct unix_sock *u = unix_sk(sk);
+
+ /*
+ * Ignore non-candidates, they could
+ * have been added to the queues after
+ * starting the garbage collection
+ */
+ if (u->gc_candidate) {
+ hit = true;
+ func(u);
+ }
}
}
if (hit && hitlist != NULL) {
@@ -249,24 +260,29 @@ static void inc_inflight_move_tail(struct unix_sock *u)
{
atomic_long_inc(&u->inflight);
/*
- * If this is still a candidate, move it to the end of the
- * list, so that it's checked even if it was already passed
- * over
+ * 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 (u->gc_candidate)
+ if (u->gc_maybe_cycle)
list_move_tail(&u->link, &gc_candidates);
}
-/* The external entry point: unix_gc() */
+static bool gc_in_progress = false;
-void unix_gc(void)
+void wait_for_unix_gc(void)
{
- static bool gc_in_progress = false;
+ wait_event(unix_gc_wait, gc_in_progress == false);
+}
+/* The external entry point: unix_gc() */
+void unix_gc(void)
+{
struct unix_sock *u;
struct unix_sock *next;
struct sk_buff_head hitlist;
struct list_head cursor;
+ LIST_HEAD(not_cycle_list);
spin_lock(&unix_gc_lock);
@@ -282,10 +298,14 @@ void unix_gc(void)
*
* Holding unix_gc_lock will protect these candidates from
* being detached, and hence from gaining an external
- * reference. This also means, that since there are no
- * possible receivers, the receive queues of these sockets are
- * static during the GC, even though the dequeue is done
- * before the detach without atomicity guarantees.
+ * 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;
@@ -299,6 +319,7 @@ void unix_gc(void)
if (total_refs == inflight_refs) {
list_move_tail(&u->link, &gc_candidates);
u->gc_candidate = 1;
+ u->gc_maybe_cycle = 1;
}
}
@@ -325,14 +346,24 @@ void unix_gc(void)
list_move(&cursor, &u->link);
if (atomic_long_read(&u->inflight) > 0) {
- list_move_tail(&u->link, &gc_inflight_list);
- u->gc_candidate = 0;
+ list_move_tail(&u->link, &not_cycle_list);
+ u->gc_maybe_cycle = 0;
scan_children(&u->sk, inc_inflight_move_tail, NULL);
}
}
list_del(&cursor);
/*
+ * not_cycle_list contains those sockets which do not make up a
+ * cycle. Restore these to the inflight list.
+ */
+ while (!list_empty(&not_cycle_list)) {
+ u = list_entry(not_cycle_list.next, struct unix_sock, link);
+ u->gc_candidate = 0;
+ list_move_tail(&u->link, &gc_inflight_list);
+ }
+
+ /*
* Now gc_candidates contains only garbage. Restore original
* inflight counters for these as well, and remove the skbuffs
* which are creating the cycle(s).
@@ -351,6 +382,7 @@ void unix_gc(void)
/* All candidates should have been detached by now. */
BUG_ON(!list_empty(&gc_candidates));
gc_in_progress = false;
+ wake_up(&unix_gc_wait);
out:
spin_unlock(&unix_gc_lock);