From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel De Graaf Subject: [PATCH 1/6 v2] xen-gntdev: Change page limit to be global instead of per-open Date: Tue, 18 Jan 2011 12:57:19 -0500 Message-ID: <4D35D47F.2050609@tycho.nsa.gov> References: <1295019976-605-1-git-send-email-dgdegra@tycho.nsa.gov> <1295019976-605-2-git-send-email-dgdegra@tycho.nsa.gov> <20110114162000.GA12102@dumpdata.com> <4D30BBA2.4050703@tycho.nsa.gov> <20110114221921.GA9523@dumpdata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110114221921.GA9523@dumpdata.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Konrad Rzeszutek Wilk Cc: jeremy@goop.org, xen-devel@lists.xensource.com, Ian.Campbell@citrix.com List-Id: xen-devel@lists.xenproject.org Because there is no limitation on how many times a user can open a given device file, an per-file-description limit on the number of pages granted offers little to no benefit. Change to a global limit and remove the ioctl() as the parameter can now be changed via sysfs. Xen tools changeset 22768:f8d801e5573e is needed to eliminate the error this change produces in xc_gnttab_set_max_grants. Signed-off-by: Daniel De Graaf --- drivers/xen/gntdev.c | 52 +++++++++++++++---------------------------------- 1 files changed, 16 insertions(+), 36 deletions(-) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 1e31cdc..59e6a51 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -45,15 +45,15 @@ MODULE_AUTHOR("Derek G. Murray , " "Gerd Hoffmann "); MODULE_DESCRIPTION("User-space granted page access driver"); -static int limit = 1024; +static int limit = 1024*1024; module_param(limit, int, 0644); -MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped at " - "once by a gntdev instance"); +MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by " + "the gntdev device"); + +static atomic_t pages_mapped = ATOMIC_INIT(0); struct gntdev_priv { struct list_head maps; - uint32_t used; - uint32_t limit; /* lock protects maps from concurrent changes */ spinlock_t lock; struct mm_struct *mm; @@ -82,9 +82,8 @@ static void gntdev_print_maps(struct gntdev_priv *priv, #ifdef DEBUG struct grant_map *map; - pr_debug("maps list (priv %p, usage %d/%d)\n", - priv, priv->used, priv->limit); - + pr_debug("%s: maps list (priv %p)\n", + __FUNCTION__, priv); list_for_each_entry(map, &priv->maps, next) pr_debug(" index %2d, count %2d %s\n", map->index, map->count, @@ -121,9 +120,6 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) add->count = count; add->priv = priv; - if (add->count + priv->used > priv->limit) - goto err; - return add; err: @@ -154,7 +150,6 @@ static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add) list_add_tail(&add->next, &priv->maps); done: - priv->used += add->count; gntdev_print_maps(priv, "[new]", add->index); } @@ -200,7 +195,7 @@ static int gntdev_del_map(struct grant_map *map) if (map->unmap_ops[i].handle) return -EBUSY; - map->priv->used -= map->count; + atomic_sub(map->count, &pages_mapped); list_del(&map->next); return 0; } @@ -386,7 +381,6 @@ static int gntdev_open(struct inode *inode, struct file *flip) INIT_LIST_HEAD(&priv->maps); spin_lock_init(&priv->lock); - priv->limit = limit; priv->mm = get_task_mm(current); if (!priv->mm) { @@ -443,19 +437,25 @@ static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, pr_debug("priv %p, add %d\n", priv, op.count); if (unlikely(op.count <= 0)) return -EINVAL; - if (unlikely(op.count > priv->limit)) - return -EINVAL; err = -ENOMEM; map = gntdev_alloc_map(priv, op.count); if (!map) return err; + if (copy_from_user(map->grants, &u->refs, sizeof(map->grants[0]) * op.count) != 0) { gntdev_free_map(map); return err; } + if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) + { + pr_debug("%s: can't map: over limit\n", __FUNCTION__); + gntdev_free_map(map); + return err; + } + spin_lock(&priv->lock); gntdev_add_map(priv, map); op.index = map->index << PAGE_SHIFT; @@ -518,23 +518,6 @@ static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, return 0; } -static long gntdev_ioctl_set_max_grants(struct gntdev_priv *priv, - struct ioctl_gntdev_set_max_grants __user *u) -{ - struct ioctl_gntdev_set_max_grants op; - - if (copy_from_user(&op, u, sizeof(op)) != 0) - return -EFAULT; - pr_debug("priv %p, limit %d\n", priv, op.count); - if (op.count > limit) - return -E2BIG; - - spin_lock(&priv->lock); - priv->limit = op.count; - spin_unlock(&priv->lock); - return 0; -} - static long gntdev_ioctl(struct file *flip, unsigned int cmd, unsigned long arg) { @@ -551,9 +534,6 @@ static long gntdev_ioctl(struct file *flip, case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); - case IOCTL_GNTDEV_SET_MAX_GRANTS: - return gntdev_ioctl_set_max_grants(priv, ptr); - default: pr_debug("priv %p, unknown cmd %x\n", priv, cmd); return -ENOIOCTLCMD;