Hello Neil,
I just realized another race problem.
svc_delete_socket() may break some queues.
Two or more threads are allowed to access the same socket at the
same time. Each of the them may call svc_delete_socket() so that
some of linked lists will be unlinked several times and might
cause oops.
And it's too bad that some of them might call svc_sock_enqueue()
to enqueue SK_DEAD sockets. It's bad to try to shuffle SK_TEMP
and SK_DEAD sockets either.
Thank you,
Hirokazu Takahashi.
--- net/sunrpc/svcsock.c.DELE Wed Nov 20 18:16:25 2030
+++ net/sunrpc/svcsock.c Wed Nov 20 20:09:48 2030
@@ -144,6 +144,12 @@ svc_sock_enqueue(struct svc_sock *svsk)
goto out_unlock;
}
+ if (test_bit(SK_DEAD, &svsk->sk_flags)) {
+ /* Don't enqueue dead sockets */
+ dprintk("svc: socket %p is dead, not enqueued\n", svsk->sk_sk);
+ goto out_unlock;
+ }
+
if (((svsk->sk_reserved + serv->sv_bufsz)*2
> sock_wspace(svsk->sk_sk))
&& !test_bit(SK_CLOSE, &svsk->sk_flags)
@@ -1179,8 +1185,10 @@ svc_recv(struct svc_serv *serv, struct s
if (test_bit(SK_TEMP, &svsk->sk_flags)) {
/* push active sockets to end of list */
spin_lock_bh(&serv->sv_lock);
- list_del(&svsk->sk_list);
- list_add_tail(&svsk->sk_list, &serv->sv_tempsocks);
+ if (test_bit(SK_TEMP, &svsk->sk_flags)) {
+ list_del(&svsk->sk_list);
+ list_add_tail(&svsk->sk_list, &serv->sv_tempsocks);
+ }
spin_unlock_bh(&serv->sv_lock);
}
@@ -1371,14 +1379,19 @@ svc_delete_socket(struct svc_sock *svsk)
spin_lock_bh(&serv->sv_lock);
- list_del(&svsk->sk_list);
- if (test_bit(SK_TEMP, &svsk->sk_flags))
- serv->sv_tmpcnt--;
- if (test_bit(SK_QUED, &svsk->sk_flags))
- list_del(&svsk->sk_ready);
-
+ if (!test_bit(SK_DEAD, &svsk->sk_flags)) {
+ list_del(&svsk->sk_list);
+ if (test_bit(SK_TEMP, &svsk->sk_flags)) {
+ serv->sv_tmpcnt--;
+ clear_bit(SK_TEMP, &svsk->sk_flags);
+ }
+ if (test_bit(SK_QUED, &svsk->sk_flags)) {
+ list_del(&svsk->sk_ready);
+ clear_bit(SK_QUED, &svsk->sk_flags);
+ }
- set_bit(SK_DEAD, &svsk->sk_flags);
+ set_bit(SK_DEAD, &svsk->sk_flags);
+ }
if (!svsk->sk_inuse) {
spin_unlock_bh(&serv->sv_lock);
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