Re: [take23 0/5] kevent: Generic event handling mechanism.

[Andrew Morton <akpm@osdl.org>]

On Tue, 7 Nov 2006 19:50:48 +0300
Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:

> Generic event handling mechanism.

I updated the version in -mm to v23.  So people can play with it and review
it.  It looks like a bit of work will be needed to get it to compile.


It seems that most of the fixes which were added to the previous version
were merged or are now irrelevant, however you lost this change:


From: Andrew Morton <akpm@osdl.org>

If kevent_user_wait() gets -EFAULT on the attempt to copy the first event, it
will return 0, which is indistinguishable from "no events pending".

It can and should return EFAULT in this case.

Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 kernel/kevent/kevent_user.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletion(-)

diff -puN kernel/kevent/kevent_user.c~kevent_user_wait-retval-fix kernel/kevent/kevent_user.c
--- a/kernel/kevent/kevent_user.c~kevent_user_wait-retval-fix
+++ a/kernel/kevent/kevent_user.c
@@ -690,8 +690,11 @@ static int kevent_user_wait(struct file 
 
 	while (num < max_nr && ((k = kqueue_dequeue_ready(u)) != NULL)) {
 		if (copy_to_user(buf + num*sizeof(struct ukevent),
-					&k->event, sizeof(struct ukevent)))
+					&k->event, sizeof(struct ukevent))) {
+			if (num == 0)
+				num = -EFAULT;
 			break;
+		}
 		kevent_complete_ready(k);
 		++num;
 		kevent_stat_wait(u);
_