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linux-next/drivers/misc/sgi-xp
Robin Holt 046d6c563b x86: uv: XPC receive message reuse triggers invalid BUG_ON()
This was a difficult bug to trip.  XPC was in the middle of sending an
acknowledgement for a received message.

In xpc_received_payload_uv():
.
        ret = xpc_send_gru_msg(ch->sn.uv.cached_notify_gru_mq_desc, msg,
                               sizeof(struct xpc_notify_mq_msghdr_uv));
        if (ret != xpSuccess)
                XPC_DEACTIVATE_PARTITION(&xpc_partitions[ch->partid], ret);

        msg->hdr.msg_slot_number += ch->remote_nentries;

at the point in xpc_send_gru_msg() where the hardware has dispatched the
acknowledgement, the remote side is able to reuse the message structure
and send a message with a different slot number.  This problem is made
worse by interrupts.

The adjustment of msg_slot_number and the BUG_ON in
xpc_handle_notify_mq_msg_uv() which verifies the msg_slot_number is
consistent are only used for debug purposes.  Since a fix for this that
preserves the debug functionality would either have to infringe upon the
payload or allocate another structure just for debug, I decided to remove
it entirely.

Signed-off-by: Robin Holt <holt@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-16 07:20:14 -08:00
..
Makefile sgi-xp: only build for ia64-sn2 when CONFIG_IA64_GENERIC specified 2008-10-30 11:38:46 -07:00
xp_main.c x86: uv: xpc needs to provide an abstraction for uv_gpa 2009-12-16 07:20:13 -08:00
xp_nofault.S [IA64] run some drivers/misc/sgi-xp through scripts/Lindent 2008-04-22 15:08:29 -07:00
xp_sn2.c x86: uv: xpc needs to provide an abstraction for uv_gpa 2009-12-16 07:20:13 -08:00
xp_uv.c x86: uv: update XPC to handle updated BIOS interface 2009-12-16 07:20:14 -08:00
xp.h x86: uv: xpc needs to provide an abstraction for uv_gpa 2009-12-16 07:20:13 -08:00
xpc_channel.c sgi-xpc: clean up numerous globals 2009-04-13 15:04:33 -07:00
xpc_main.c sysctl: Drop & in front of every proc_handler. 2009-11-18 08:37:40 -08:00
xpc_partition.c x86: uv: update XPC to handle updated BIOS interface 2009-12-16 07:20:14 -08:00
xpc_sn2.c [IA64] sgi-xp: fix printk format warnings 2009-09-15 08:44:03 -07:00
xpc_uv.c x86: uv: XPC receive message reuse triggers invalid BUG_ON() 2009-12-16 07:20:14 -08:00
xpc.h sgi-xpc: clean up numerous globals 2009-04-13 15:04:33 -07:00
xpnet.c drivers: Kill now superfluous ->last_rx stores 2009-09-02 23:07:36 -07:00