eventfd: revised interface and cleanups

Change the eventfd interface to de-couple the eventfd memory context, from
the file pointer instance.

Without such change, there is no clean way to racely free handle the
POLLHUP event sent when the last instance of the file* goes away.  Also,
now the internal eventfd APIs are using the eventfd context instead of the
file*.

This patch is required by KVM's IRQfd code, which is still under
development.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Gregory Haskins <ghaskins@novell.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 3 deletions

diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index d4e8979735cb..9c3138265f8e 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -82,7 +82,7 @@ struct lg_cpu {
 
 struct lg_eventfd {
         unsigned long addr;
-        struct file *event;
+        struct eventfd_ctx *event;
 };
 
 struct lg_eventfd_map {
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 32e297121058..9f9a2953b383 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -50,7 +50,7 @@ static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
 
         /* Now append new entry. */
         new->map[new->num].addr = addr;
-        new->map[new->num].event = eventfd_fget(fd);
+        new->map[new->num].event = eventfd_ctx_fdget(fd);
         if (IS_ERR(new->map[new->num].event)) {
                 kfree(new);
                 return PTR_ERR(new->map[new->num].event);
@@ -357,7 +357,7 @@ static int close(struct inode *inode, struct file *file)
 
         /* Release any eventfds they registered. */
         for (i = 0; i < lg->eventfds->num; i++)
-                fput(lg->eventfds->map[i].event);
+                eventfd_ctx_put(lg->eventfds->map[i].event);
         kfree(lg->eventfds);
 
         /* If lg->dead doesn't contain an error code it will be NULL or a