[PATCH] 2.5 fast poll on ppc64

[Anton Blanchard <anton@samba.org>]

Hi,

I was unable to boot 2.5-BK on ppc64 and narrowed it down to the fast
poll patch.  I found:

offsetof(struct poll_list, entries) == 12 but
sizeof(struct poll_list) == 16

This means pp+1 did not match up with pp->entries. Im not sure what the
alignment requirements are for a zero length struct (ie is this a
compiler bug) but the following patch fixes the problem and also changes
->len to a long to ensure 8 byte alignment of ->entries on 64bit archs.

Anton

===== fs/select.c 1.15 vs edited =====
--- 1.15/fs/select.c	Sat Dec 21 20:42:41 2002
+++ edited/fs/select.c	Thu Dec 26 17:31:16 2002
@@ -362,7 +362,7 @@
 
 struct poll_list {
 	struct poll_list *next;
-	int len;
+	long len;
 	struct pollfd entries[0];
 };
 
@@ -471,7 +471,7 @@
 			walk->next = pp;
 
 		walk = pp;
-		if (copy_from_user(pp+1, ufds + nfds-i, 
+		if (copy_from_user(pp->entries, ufds + nfds-i, 
 				sizeof(struct pollfd)*pp->len)) {
 			err = -EFAULT;
 			goto out_fds;