diff options
| -rw-r--r-- | sys/netgraph/ng_base.c | 100 |
1 files changed, 36 insertions, 64 deletions
diff --git a/sys/netgraph/ng_base.c b/sys/netgraph/ng_base.c index 2327b4d..476e672 100644 --- a/sys/netgraph/ng_base.c +++ b/sys/netgraph/ng_base.c @@ -70,6 +70,9 @@ MODULE_VERSION(netgraph, NG_ABI_VERSION); static LIST_HEAD(, ng_node) ng_nodelist; static struct mtx ng_nodelist_mtx; +/* Mutex that protects the free queue item list */ +static struct mtx ngq_mtx; + #ifdef NETGRAPH_DEBUG static SLIST_HEAD(, ng_node) ng_allnodes; @@ -176,9 +179,6 @@ static struct mtx ng_idhash_mtx; } \ } while (0) -/* Mutex that protects the free queue item list */ -static volatile item_p ngqfree; /* free ones */ -static struct mtx ngq_mtx; /* Internal functions */ static int ng_add_hook(node_p node, const char *name, hook_p * hookp); @@ -2984,7 +2984,7 @@ ngb_mod_event(module_t mod, int event, void *data) mtx_init(&ng_typelist_mtx, "netgraph types mutex", NULL, 0); mtx_init(&ng_nodelist_mtx, "netgraph nodelist mutex", NULL, 0); mtx_init(&ng_idhash_mtx, "netgraph idhash mutex", NULL, 0); - mtx_init(&ngq_mtx, "netgraph netisr mutex", NULL, 0); + mtx_init(&ngq_mtx, "netgraph free item list mutex", NULL, 0); s = splimp(); netisr_register(NETISR_NETGRAPH, (netisr_t *)ngintr, NULL); splx(s); @@ -3030,6 +3030,8 @@ SYSCTL_INT(_net_graph, OID_AUTO, ngqfreemax, CTLFLAG_RDTUN, &ngqfreemax, static const int ngqfreelow = 4; /* try malloc if free < this */ static volatile int ngqfreesize; /* number of cached entries */ +static volatile item_p ngqfree; /* free ones */ + #ifdef NETGRAPH_DEBUG static TAILQ_HEAD(, ng_item) ng_itemlist = TAILQ_HEAD_INITIALIZER(ng_itemlist); #endif @@ -3038,8 +3040,7 @@ static TAILQ_HEAD(, ng_item) ng_itemlist = TAILQ_HEAD_INITIALIZER(ng_itemlist); * This is usually called when a packet first enters netgraph. * By definition, this is usually from an interrupt, or from a user. * Users are not so important, but try be quick for the times that it's - * an interrupt. Use atomic operations to cope with collisions - * with interrupts and other processors. Assumes MALLOC is SMP safe. + * an interrupt. * XXX If reserve is low, we should try to get 2 from malloc as this * would indicate it often fails. */ @@ -3052,60 +3053,38 @@ ng_getqblk(void) * Try get a cached queue block, or else allocate a new one * If we are less than our reserve, try malloc. If malloc * fails, then that's what the reserve is for... - * Don't completely trust ngqfreesize, as it is subject - * to races.. (it'll eventually catch up but may be out by one or two - * for brief moments(under SMP or interrupts). - * ngqfree is the final arbiter. We have our little reserve + * We have our little reserve * because we use M_NOWAIT for malloc. This just helps us * avoid dropping packets while not increasing the time * we take to service the interrupt (on average) (I hope). */ - for (;;) { - if ((ngqfreesize < ngqfreelow) || (ngqfree == NULL)) { - if (allocated < maxalloc) { /* don't leak forever */ - MALLOC(item, item_p , - sizeof(*item), M_NETGRAPH_ITEM, - (M_NOWAIT | M_ZERO)); - if (item) { + mtx_lock(&ngq_mtx); + + if ((ngqfreesize < ngqfreelow) || (ngqfree == NULL)) { + if (allocated < maxalloc) { /* don't leak forever */ + MALLOC(item, item_p , + sizeof(*item), M_NETGRAPH_ITEM, + (M_NOWAIT | M_ZERO)); + if (item) { #ifdef NETGRAPH_DEBUG - TAILQ_INSERT_TAIL(&ng_itemlist, - item, all); + TAILQ_INSERT_TAIL(&ng_itemlist, item, all); #endif /* NETGRAPH_DEBUG */ - atomic_add_int(&allocated, 1); - break; - } + allocated++; } } + } - /* - * We didn't or couldn't malloc. - * try get one from our cache. - * item must be NULL to get here. - */ - if ((item = ngqfree) != NULL) { - /* - * Atomically try grab the first item - * and put it's successor in its place. - * If we fail, just try again.. someone else - * beat us to this one or freed one. - * Don't worry about races with ngqfreesize. - * Close enough is good enough.. - */ - if (atomic_cmpset_ptr(&ngqfree, item, item->el_next)) { - atomic_subtract_int(&ngqfreesize, 1); - item->el_flags &= ~NGQF_FREE; - break; - } - /* - * something got there before we did.. try again - * (go around the loop again) - */ - item = NULL; - } else { - /* We really ran out */ - break; - } + /* + * We didn't or couldn't malloc. + * try get one from our cache. + */ + if (item == NULL && (item = ngqfree) != NULL) { + ngqfree = item->el_next; + ngqfreesize--; + item->el_flags &= ~NGQF_FREE; } + + mtx_unlock(&ngq_mtx); return (item); } @@ -3149,26 +3128,19 @@ ng_free_item(item_p item) _NGI_CLR_HOOK(item); item->el_flags |= NGQF_FREE; - /* - * We have freed any resources held by the item. - * now we can free the item itself. - */ - if (ngqfreesize < ngqfreemax) { /* don't worry about races */ - for (;;) { - item->el_next = ngqfree; - if (atomic_cmpset_ptr(&ngqfree, item->el_next, item)) { - break; - } - } - atomic_add_int(&ngqfreesize, 1); + mtx_lock(&ngq_mtx); + if (ngqfreesize < ngqfreemax) { + ngqfreesize++; + item->el_next = ngqfree; + ngqfree = item; } else { - /* This is the only place that should use this Macro */ #ifdef NETGRAPH_DEBUG TAILQ_REMOVE(&ng_itemlist, item, all); #endif /* NETGRAPH_DEBUG */ NG_FREE_ITEM_REAL(item); - atomic_subtract_int(&allocated, 1); + allocated--; } + mtx_unlock(&ngq_mtx); } #ifdef NETGRAPH_DEBUG |
