Date: Fri, 5 Jul 2013 14:12:27 +0000 (UTC) From: Andre Oppermann <andre@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r252783 - stable/9/sys/kern Message-ID: <201307051412.r65ECRRM053426@svn.freebsd.org>
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Author: andre Date: Fri Jul 5 14:12:26 2013 New Revision: 252783 URL: http://svnweb.freebsd.org/changeset/base/252783 Log: MFC r243627, r243638: Fix a race on listen socket teardown where while draining the accept queues a new socket/connection may be added to the queue due to a race on the ACCEPT_LOCK. The submitted patch is slightly changed in comments, teardown and locking order and extended with KASSERT's. Submitted by: Vijay Singh <vijju.singh-at-gmail-dot-com> Found by: His team. Modified: stable/9/sys/kern/uipc_socket.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/kern/uipc_socket.c ============================================================================== --- stable/9/sys/kern/uipc_socket.c Fri Jul 5 14:08:36 2013 (r252782) +++ stable/9/sys/kern/uipc_socket.c Fri Jul 5 14:12:26 2013 (r252783) @@ -502,6 +502,16 @@ sonewconn(struct socket *head, int conns so->so_snd.sb_flags |= head->so_snd.sb_flags & SB_AUTOSIZE; so->so_state |= connstatus; ACCEPT_LOCK(); + /* + * The accept socket may be tearing down but we just + * won a race on the ACCEPT_LOCK. + */ + if (!(head->so_options & SO_ACCEPTCONN)) { + SOCK_LOCK(so); + so->so_head = NULL; + sofree(so); /* NB: returns ACCEPT_UNLOCK'ed. */ + return (NULL); + } if (connstatus) { TAILQ_INSERT_TAIL(&head->so_comp, so, so_list); so->so_qstate |= SQ_COMP; @@ -727,9 +737,14 @@ soclose(struct socket *so) drop: if (so->so_proto->pr_usrreqs->pru_close != NULL) (*so->so_proto->pr_usrreqs->pru_close)(so); + ACCEPT_LOCK(); if (so->so_options & SO_ACCEPTCONN) { struct socket *sp; - ACCEPT_LOCK(); + /* + * Prevent new additions to the accept queues due + * to ACCEPT_LOCK races while we are draining them. + */ + so->so_options &= ~SO_ACCEPTCONN; while ((sp = TAILQ_FIRST(&so->so_incomp)) != NULL) { TAILQ_REMOVE(&so->so_incomp, sp, so_list); so->so_incqlen--; @@ -748,13 +763,15 @@ drop: soabort(sp); ACCEPT_LOCK(); } - ACCEPT_UNLOCK(); + KASSERT((TAILQ_EMPTY(&so->so_comp)), + ("%s: so_comp populated", __func__)); + KASSERT((TAILQ_EMPTY(&so->so_incomp)), + ("%s: so_incomp populated", __func__)); } - ACCEPT_LOCK(); SOCK_LOCK(so); KASSERT((so->so_state & SS_NOFDREF) == 0, ("soclose: NOFDREF")); so->so_state |= SS_NOFDREF; - sorele(so); + sorele(so); /* NB: Returns with ACCEPT_UNLOCK(). */ CURVNET_RESTORE(); return (error); }
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