Re: [PATCH 9/24] make atomic_read() behave consistently on ia64

Luck, Tony wrote:

quoted

Use atomic64_read to read an atomic64_t.

Thanks Andreas!

Chris: This bug is why the 8-byte loads got changed to 4-byte + sign-extend
by your change to atomic_read().

I figured as much.  Thanks for confirming this.

With this applied together with shuffling the volatile from the
declaration to the usage (in both atomic_read() and atomic_set()
the generated code *almost* reverts to the original.

There are some differences where ld4 have turned into ld8 though.
Are these bugs in the use of atomic_add() and atomic_sub().  E.g.
the first of these changes is in: ipc/msg.c:freeque() where we have:

	atomic_sub(msg->q_cbytes, &msg_bytes);

Now the type of msg->q_cbytes is "unsigned long" ... so it seems a
poor idea to subtract such a large typed object from "msg_bytes"
which is a mere slip of an atomic_t.

Or is there some other type-wrangling that needs to happen in
include/asm-ia64/atomic.h?  There are a total of nineteen of
these ld4->ld8 transforms.

Possibly.  Either that or we've uncovered some latent bugs.  Maybe a 
combination of the two.  Can you list those 19 changes so we can 
evaluate them?  I'm told there were some *(volatile *) bugs fixed in gcc 
recently, so it's also possible your 3.4.6 is showing those.  I can test 
that on a more recent gcc on ia64 if it's inconvenient for you to do so 
on your test box.

	-- Chris