[PATCH] 2.5 fast poll on ppc64

Anton Blanchard
2002-12-26T06:40:50Z

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;