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mirror of https://git.FreeBSD.org/src.git synced 2024-12-24 11:29:10 +00:00

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)
This commit is contained in:
Gleb Smirnoff 2005-07-05 17:35:20 +00:00
parent 7906787a5f
commit 8afe16d57b
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=147774
4 changed files with 82 additions and 3 deletions

View File

@ -580,6 +580,7 @@ _ng_node_foreach_hook(node_p node, ng_fn_eachhook *fn, void *arg,
*
*/
typedef void ng_item_fn(node_p node, hook_p hook, void *arg1, int arg2);
typedef void ng_apply_t(void *context, int error);
struct ng_item {
u_long el_flags;
item_p el_next;
@ -597,6 +598,12 @@ struct ng_item {
int fn_arg2;
} fn;
} body;
/*
* Optional callback called when item is being applied,
* and its context.
*/
ng_apply_t *apply;
void *context;
#ifdef NETGRAPH_DEBUG /*----------------------------------------------*/
char *lastfile;
int lastline;
@ -1084,6 +1091,7 @@ int ng_callout(struct callout *c, node_p node, hook_p hook, int ticks,
#define NG_NOFLAGS 0x00000000 /* no special options */
#define NG_QUEUE 0x00000001 /* enqueue item, don't dispatch */
#define NG_WAITOK 0x00000002 /* use M_WAITOK, etc. */
#define NG_PROGRESS 0x00000004 /* return EINPROGRESS if queued */
/*
* prototypes the user should DEFINITELY not use directly

View File

@ -2211,7 +2211,11 @@ ng_snd_item(item_p item, int flags)
ng_setisr(node);
}
mtx_unlock_spin(&(ngq->q_mtx));
return (0);
if (flags & NG_PROGRESS)
return (EINPROGRESS);
else
return (0);
}
/*
* Take a queue item and a node and see if we can apply the item to
@ -2237,7 +2241,10 @@ ng_snd_item(item_p item, int flags)
* have been queued in thises cases.
*/
if (item == NULL) {
return (0);
if (flags & NG_PROGRESS)
return (EINPROGRESS);
else
return (0);
}
#ifdef NETGRAPH_DEBUG
@ -2333,11 +2340,25 @@ ng_apply_item(node_p node, item_p item)
int error = 0;
ng_rcvdata_t *rcvdata;
ng_rcvmsg_t *rcvmsg;
ng_apply_t *apply = NULL;
void *context = NULL;
NGI_GET_HOOK(item, hook); /* clears stored hook */
#ifdef NETGRAPH_DEBUG
_ngi_check(item, __FILE__, __LINE__);
#endif
/*
* If item has apply callback, store it. Clear callback
* immediately, two avoid another call in case if
* item would be reused by destination node.
*/
if (item->apply != NULL) {
apply = item->apply;
context = item->context;
item->apply = NULL;
}
switch (item->el_flags & NGQF_TYPE) {
case NGQF_DATA:
/*
@ -2453,6 +2474,11 @@ ng_apply_item(node_p node, item_p item)
} else {
ng_leave_write(&node->nd_input_queue);
}
/* Apply callback. */
if (apply != NULL)
(*apply)(context, error);
return (error);
}

View File

@ -131,6 +131,7 @@ static int ng_bind(struct sockaddr *nam, struct ngpcb *pcbp);
static int ngs_mod_event(module_t mod, int event, void *data);
static int ship_msg(struct ngpcb *pcbp, struct ng_mesg *msg,
struct sockaddr_ng *addr);
static void ng_socket_item_applied(void *context, int error);
/* Netgraph type descriptor */
static struct ng_type typestruct = {
@ -208,6 +209,7 @@ ngc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *addr,
struct mbuf *control, struct thread *td)
{
struct ngpcb *const pcbp = sotongpcb(so);
struct ngsock *const priv = NG_NODE_PRIVATE(pcbp->sockdata->node);
struct sockaddr_ng *const sap = (struct sockaddr_ng *) addr;
struct ng_mesg *msg;
struct mbuf *m0;
@ -332,7 +334,29 @@ ngc_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *addr,
item->el_dest->nd_type->name);
#endif
SAVE_LINE(item);
error = ng_snd_item(item, NG_NOFLAGS);
/*
* We do not want to return from syscall until the item
* is processed by destination node. We register callback
* on the item, which will update priv->error when item
* was applied.
* If ng_snd_item() has queued item, we sleep until
* callback wakes us up.
*/
item->apply = ng_socket_item_applied;
item->context = priv;
priv->error = -1;
error = ng_snd_item(item, NG_PROGRESS);
if (error == EINPROGRESS) {
mtx_lock(&priv->mtx);
if (priv->error == -1)
msleep(priv, &priv->mtx, 0, "ngsock", 0);
mtx_unlock(&priv->mtx);
KASSERT(priv->error != -1,
("ng_socket: priv->error wasn't updated"));
error = priv->error;
}
release:
if (path != NULL)
@ -553,6 +577,8 @@ ng_attach_cntl(struct socket *so)
}
NG_NODE_SET_PRIVATE(privdata->node, privdata);
mtx_init(&privdata->mtx, "ng_socket", NULL, MTX_DEF);
/* Link the pcb and the node private data */
privdata->ctlsock = pcbp;
pcbp->sockdata = privdata;
@ -813,6 +839,10 @@ ship_msg(struct ngpcb *pcbp, struct ng_mesg *msg, struct sockaddr_ng *addr)
return (0);
}
/***************************************************************
Netgraph node
***************************************************************/
/*
* You can only create new nodes from the socket end of things.
*/
@ -1020,10 +1050,23 @@ ngs_shutdown(node_p node)
}
NG_NODE_SET_PRIVATE(node, NULL);
NG_NODE_UNREF(node);
mtx_destroy(&priv->mtx);
FREE(priv, M_NETGRAPH_SOCK);
return (0);
}
static void
ng_socket_item_applied(void *context, int error)
{
struct ngsock *const priv = (struct ngsock *)context;
mtx_lock(&priv->mtx);
priv->error = error;
wakeup(priv);
mtx_unlock(&priv->mtx);
}
static int
dummy_disconnect(struct socket *so)
{

View File

@ -59,6 +59,8 @@ struct ngsock {
struct ngpcb *ctlsock; /* optional control socket */
int flags;
int refs;
struct mtx mtx; /* mtx to wait on */
int error; /* place to store error */
};
#define NGS_FLAG_NOLINGER 1 /* close with last hook */