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| author | Robin Holt <holt@sgi.com> | 2009-12-16 01:47:59 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-16 16:20:14 +0100 |
| commit | 046d6c563b1c6226bbf0f84e5b2413ad8ab921a1 (patch) | |
| tree | ba88e7f89618421bd320f5f55d06b4ad7839938e /drivers/misc/sgi-xp | |
| parent | X86: uv: xpc_make_first_contact hang due to not accepting ACTIVE state (diff) | |
| download | linux-046d6c563b1c6226bbf0f84e5b2413ad8ab921a1.tar.xz linux-046d6c563b1c6226bbf0f84e5b2413ad8ab921a1.zip | |
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>
Diffstat (limited to 'drivers/misc/sgi-xp')
| -rw-r--r-- | drivers/misc/sgi-xp/xpc_uv.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c index 241ea5f01aaa..d2f4e9121f93 100644 --- a/drivers/misc/sgi-xp/xpc_uv.c +++ b/drivers/misc/sgi-xp/xpc_uv.c @@ -1428,7 +1428,6 @@ xpc_handle_notify_mq_msg_uv(struct xpc_partition *part, msg_slot = ch_uv->recv_msg_slots + (msg->hdr.msg_slot_number % ch->remote_nentries) * ch->entry_size; - BUG_ON(msg->hdr.msg_slot_number != msg_slot->hdr.msg_slot_number); BUG_ON(msg_slot->hdr.size != 0); memcpy(msg_slot, msg, msg->hdr.size); @@ -1652,8 +1651,6 @@ xpc_received_payload_uv(struct xpc_channel *ch, void *payload) 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; } static struct xpc_arch_operations xpc_arch_ops_uv = { |