[PATCH] Avoid unnecessary copy for EPOLL_CTL_DEL

[PATCH] Avoid unnecessary copy for EPOLL_CTL_DEL

[Ulrich Drepper]

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When epoll_ctl() is used with the EPOLL_CTL_DEL operation the event
structure pointed to by the fourth parameter is unnecessarily copied.
It is not used and userlevel would have to initialize some memory to
avoid passing down a pointer to some uninitialized memory.  The attached
patch should work just fine.

Signed-off-by: Ulrich Drepper <drepper@redhat.com>

- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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--- fs/eventpoll.c	2004-08-26 19:14:51.000000000 -0700
+++ fs/eventpoll.c.new	2004-10-03 00:04:33.000000000 -0700
@@ -531,7 +531,8 @@ sys_epoll_ctl(int epfd, int op, int fd, 
 		     current, epfd, op, fd, event));
 
 	error = -EFAULT;
-	if (copy_from_user(&epds, event, sizeof(struct epoll_event)))
+	if (op != EPOLL_CTL_DEL &&
+	    copy_from_user(&epds, event, sizeof(struct epoll_event)))
 		goto eexit_1;
 
 	/* Get the "struct file *" for the eventpoll file */