From 0cc678f850f2cba0cedbd133fcbbf175554cd6c6 Mon Sep 17 00:00:00 2001 From: Daniel De Graaf Date: Thu, 27 Oct 2011 17:58:49 -0400 Subject: xen/gnt{dev,alloc}: reserve event channels for notify When using the unmap notify ioctl, the event channel used for notification needs to be reserved to avoid it being deallocated prior to sending the notification. Signed-off-by: Daniel De Graaf Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/gntdev.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) (limited to 'drivers/xen/gntdev.c') diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 39871326afa2..a7308559a26a 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -193,8 +193,10 @@ static void gntdev_put_map(struct grant_map *map) atomic_sub(map->count, &pages_mapped); - if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) + if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { notify_remote_via_evtchn(map->notify.event); + evtchn_put(map->notify.event); + } if (map->pages) { if (!use_ptemod) @@ -599,6 +601,8 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) struct ioctl_gntdev_unmap_notify op; struct grant_map *map; int rc; + int out_flags; + unsigned int out_event; if (copy_from_user(&op, u, sizeof(op))) return -EFAULT; @@ -606,6 +610,21 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) return -EINVAL; + /* We need to grab a reference to the event channel we are going to use + * to send the notify before releasing the reference we may already have + * (if someone has called this ioctl twice). This is required so that + * it is possible to change the clear_byte part of the notification + * without disturbing the event channel part, which may now be the last + * reference to that event channel. + */ + if (op.action & UNMAP_NOTIFY_SEND_EVENT) { + if (evtchn_get(op.event_channel_port)) + return -EINVAL; + } + + out_flags = op.action; + out_event = op.event_channel_port; + spin_lock(&priv->lock); list_for_each_entry(map, &priv->maps, next) { @@ -624,12 +643,22 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) goto unlock_out; } + out_flags = map->notify.flags; + out_event = map->notify.event; + map->notify.flags = op.action; map->notify.addr = op.index - (map->index << PAGE_SHIFT); map->notify.event = op.event_channel_port; + rc = 0; + unlock_out: spin_unlock(&priv->lock); + + /* Drop the reference to the event channel we did not save in the map */ + if (out_flags & UNMAP_NOTIFY_SEND_EVENT) + evtchn_put(out_event); + return rc; } -- cgit v1.2.3 From 7d17e84bb8356b1d9f4402dd82a0e270a3d59a4f Mon Sep 17 00:00:00 2001 From: Daniel De Graaf Date: Wed, 14 Dec 2011 15:12:11 -0500 Subject: xen/grant-table: Support mappings required by blkback Add support for mappings without GNTMAP_contains_pte. This was not supported because the unmap operation assumed that this flag was being used; adding a parameter to the unmap operation to allow the PTE clearing to be disabled is sufficient to make unmap capable of supporting either mapping type. Signed-off-by: Daniel De Graaf [v1: Fix cleanpatch warnings] Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/gntdev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/xen/gntdev.c') diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index f52f661f8f82..99d8151c824a 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -314,7 +314,8 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages) } } - err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages); + err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, + pages, true); if (err) return err; -- cgit v1.2.3