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Part two of post-SMPng cleanup of accept filter registration: perform all

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allocation up front before grabbing the socket mutex and doing the
registration work.  The result is a lot cleaner.
This commit is contained in:
Robert Watson 2005-03-12 12:27:47 +00:00
parent 6efbc8f412
commit 92081a8344
1 changed files with 16 additions and 34 deletions
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50
sys/kern/uipc_accf.c
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@ -195,34 +195,12 @@ do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
return (0);
}
newaf = NULL;
afap = NULL;
/*
* XXXRW: Configuring accept filters should be an atomic test-and-set
* operation to prevent races during setup and attach. There may be
* more general issues of racing and ordering here that are not yet
* addressed by locking.
*/
/* do not set/remove accept filters on non listen sockets */
SOCK_LOCK(so);
if ((so->so_options & SO_ACCEPTCONN) == 0) {
SOCK_UNLOCK(so);
return (EINVAL);
}
SOCK_UNLOCK(so);
/*-
* Adding a filter.
*
* Do memory allocation, copyin, and filter lookup now while we're
* not holding any locks. Avoids sleeping with a mutex, as well as
* introducing a lock order between accept filter locks and socket
* locks here.
* Pre-allocate any memory we may need later to avoid blocking at
* untimely moments. This does not optimize for invalid arguments.
*/
MALLOC(afap, struct accept_filter_arg *, sizeof(*afap), M_TEMP,
M_WAITOK);
/* don't put large objects on the kernel stack */
error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
afap->af_name[sizeof(afap->af_name)-1] = '\0';
afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
@ -235,11 +213,11 @@ do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
FREE(afap, M_TEMP);
return (ENOENT);
}
/*
* Allocate the new accept filter instance storage. We may have to
* free it again later if we fail to attach it. If attached
* properly, 'newaf' is NULLed to avoid a free() while in use.
* Allocate the new accept filter instance storage. We may
* have to free it again later if we fail to attach it. If
* attached properly, 'newaf' is NULLed to avoid a free()
* while in use.
*/
MALLOC(newaf, struct so_accf *, sizeof(*newaf), M_ACCF, M_WAITOK |
M_ZERO);
@ -250,17 +228,21 @@ do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
strcpy(newaf->so_accept_filter_str, afap->af_name);
}
/*
* Require a listen socket; don't try to replace an existing filter
* without first removing it.
*/
SOCK_LOCK(so);
/* must remove previous filter first */
if (so->so_accf != NULL) {
if (((so->so_options & SO_ACCEPTCONN) == 0) ||
(so->so_accf != NULL)) {
error = EINVAL;
goto out;
}
/*
* Invoke the accf_create() method of the filter if required.
* XXXRW: the socket mutex is held over this call, so the create
* method cannot block. This may be something we have to change, but
* it would require addressing possible races.
* Invoke the accf_create() method of the filter if required. The
* socket mutex is held over this call, so create methods for filters
* can't block.
*/
if (afp->accf_create != NULL) {
newaf->so_accept_filter_arg =