In the splnet times, netgraph was functional and synchronous. Nowadays,
an item may be queued and processed later. While this is OK for mbufs, this is a problem for control messages. In the framework: - Add optional callback function pointer to an item. When item gets applied the callback is executed from ng_apply_item(). - Add new flag NG_PROGRESS. If this flag is supplied, then return EINPROGRESS instead of 0 in case if item failed to deliver synchronously and was queued. - Honor NG_PROGRESS in ng_snd_item(). In ng_socket: - When userland sends control message add callback to the item. - If ng_snd_item() returns EINPROGRESS, then sleep. This change fixes possible races in ngctl(8) scripts. Reviewed by: julian Approved by: re (scottl)
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=147774
@ -580,6 +580,7 @@ _ng_node_foreach_hook(node_p node, ng_fn_eachhook *fn, void *arg,
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*
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*/
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typedef void ng_item_fn(node_p node, hook_p hook, void *arg1, int arg2);
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typedef void ng_apply_t(void *context, int error);
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struct ng_item {
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u_long el_flags;
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item_p el_next;
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@ -597,6 +598,12 @@ struct ng_item {
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int fn_arg2;
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} fn;
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} body;
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/*
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* Optional callback called when item is being applied,
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* and its context.
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*/
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ng_apply_t *apply;
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void *context;
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#ifdef NETGRAPH_DEBUG /*----------------------------------------------*/
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char *lastfile;
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int lastline;
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@ -1084,6 +1091,7 @@ int ng_callout(struct callout *c, node_p node, hook_p hook, int ticks,
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#define NG_NOFLAGS 0x00000000 /* no special options */
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#define NG_QUEUE 0x00000001 /* enqueue item, don't dispatch */
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#define NG_WAITOK 0x00000002 /* use M_WAITOK, etc. */
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#define NG_PROGRESS 0x00000004 /* return EINPROGRESS if queued */
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/*
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* prototypes the user should DEFINITELY not use directly
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@ -2211,7 +2211,11 @@ ng_snd_item(item_p item, int flags)
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ng_setisr(node);
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}
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mtx_unlock_spin(&(ngq->q_mtx));
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return (0);
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if (flags & NG_PROGRESS)
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return (EINPROGRESS);
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else
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return (0);
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}
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/*
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* Take a queue item and a node and see if we can apply the item to
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@ -2237,7 +2241,10 @@ ng_snd_item(item_p item, int flags)
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* have been queued in thises cases.
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*/
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if (item == NULL) {
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return (0);
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if (flags & NG_PROGRESS)
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return (EINPROGRESS);
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else
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return (0);
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}
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#ifdef NETGRAPH_DEBUG
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@ -2333,11 +2340,25 @@ ng_apply_item(node_p node, item_p item)
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int error = 0;
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ng_rcvdata_t *rcvdata;
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ng_rcvmsg_t *rcvmsg;
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ng_apply_t *apply = NULL;
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void *context = NULL;
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NGI_GET_HOOK(item, hook); /* clears stored hook */
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#ifdef NETGRAPH_DEBUG
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_ngi_check(item, __FILE__, __LINE__);
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#endif
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/*
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* If item has apply callback, store it. Clear callback
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* immediately, two avoid another call in case if
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* item would be reused by destination node.
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*/
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if (item->apply != NULL) {
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apply = item->apply;
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context = item->context;
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item->apply = NULL;
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}
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switch (item->el_flags & NGQF_TYPE) {
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case NGQF_DATA:
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/*
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@ -2453,6 +2474,11 @@ ng_apply_item(node_p node, item_p item)
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} else {
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ng_leave_write(&node->nd_input_queue);
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}
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/* Apply callback. */
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if (apply != NULL)
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(*apply)(context, error);
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return (error);
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}
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@ -131,6 +131,7 @@ static int ng_bind(struct sockaddr *nam, struct ngpcb *pcbp);
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static int ngs_mod_event(module_t mod, int event, void *data);
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static int ship_msg(struct ngpcb *pcbp, struct ng_mesg *msg,
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struct sockaddr_ng *addr);
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static void ng_socket_item_applied(void *context, int error);
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/* Netgraph type descriptor */
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static struct ng_type typestruct = {
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@ -208,6 +209,7 @@ ngc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *addr,
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struct mbuf *control, struct thread *td)
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{
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struct ngpcb *const pcbp = sotongpcb(so);
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struct ngsock *const priv = NG_NODE_PRIVATE(pcbp->sockdata->node);
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struct sockaddr_ng *const sap = (struct sockaddr_ng *) addr;
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struct ng_mesg *msg;
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struct mbuf *m0;
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@ -332,7 +334,29 @@ ngc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *addr,
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item->el_dest->nd_type->name);
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#endif
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SAVE_LINE(item);
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error = ng_snd_item(item, NG_NOFLAGS);
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/*
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* We do not want to return from syscall until the item
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* is processed by destination node. We register callback
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* on the item, which will update priv->error when item
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* was applied.
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* If ng_snd_item() has queued item, we sleep until
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* callback wakes us up.
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*/
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item->apply = ng_socket_item_applied;
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item->context = priv;
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priv->error = -1;
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error = ng_snd_item(item, NG_PROGRESS);
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if (error == EINPROGRESS) {
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mtx_lock(&priv->mtx);
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if (priv->error == -1)
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msleep(priv, &priv->mtx, 0, "ngsock", 0);
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mtx_unlock(&priv->mtx);
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KASSERT(priv->error != -1,
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("ng_socket: priv->error wasn't updated"));
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error = priv->error;
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}
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release:
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if (path != NULL)
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@ -553,6 +577,8 @@ ng_attach_cntl(struct socket *so)
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}
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NG_NODE_SET_PRIVATE(privdata->node, privdata);
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mtx_init(&privdata->mtx, "ng_socket", NULL, MTX_DEF);
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/* Link the pcb and the node private data */
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privdata->ctlsock = pcbp;
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pcbp->sockdata = privdata;
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@ -813,6 +839,10 @@ ship_msg(struct ngpcb *pcbp, struct ng_mesg *msg, struct sockaddr_ng *addr)
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return (0);
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}
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/***************************************************************
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Netgraph node
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***************************************************************/
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/*
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* You can only create new nodes from the socket end of things.
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*/
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@ -1020,10 +1050,23 @@ ngs_shutdown(node_p node)
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}
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NG_NODE_SET_PRIVATE(node, NULL);
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NG_NODE_UNREF(node);
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mtx_destroy(&priv->mtx);
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FREE(priv, M_NETGRAPH_SOCK);
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return (0);
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}
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static void
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ng_socket_item_applied(void *context, int error)
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{
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struct ngsock *const priv = (struct ngsock *)context;
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mtx_lock(&priv->mtx);
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priv->error = error;
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wakeup(priv);
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mtx_unlock(&priv->mtx);
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}
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static int
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dummy_disconnect(struct socket *so)
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{
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@ -59,6 +59,8 @@ struct ngsock {
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struct ngpcb *ctlsock; /* optional control socket */
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int flags;
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int refs;
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struct mtx mtx; /* mtx to wait on */
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int error; /* place to store error */
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};
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#define NGS_FLAG_NOLINGER 1 /* close with last hook */
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