The patch titled
x86: uv: XPC receive message reuse triggers invalid BUG_ON()
has been added to the -mm tree. Its filename is
x86-uv-xpc-receive-message-reuse-triggers-invalid-bug_on.patch
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Subject: x86: uv: XPC receive message reuse triggers invalid BUG_ON()
From: Robin Holt <holt@xxxxxxx>
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@xxxxxxx>
Cc: Jack Steiner <steiner@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/misc/sgi-xp/xpc_uv.c | 3 ---
1 file changed, 3 deletions(-)
diff -puN drivers/misc/sgi-xp/xpc_uv.c~x86-uv-xpc-receive-message-reuse-triggers-invalid-bug_on drivers/misc/sgi-xp/xpc_uv.c
--- a/drivers/misc/sgi-xp/xpc_uv.c~x86-uv-xpc-receive-message-reuse-triggers-invalid-bug_on
+++ a/drivers/misc/sgi-xp/xpc_uv.c
@@ -1428,7 +1428,6 @@ xpc_handle_notify_mq_msg_uv(struct xpc_p
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_chann
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 = {
_
Patches currently in -mm which might be from holt@xxxxxxx are
x86-uv-introduce-a-means-to-translate-from-gpa-socket_paddr.patch
x86-uv-xpc-needs-to-provide-an-abstraction-for-uv_gpa.patch
x86-uv-introduce-uv_gpa_is_mmr.patch
x86-uv-implement-a-gru_read_gpa-kernel-function.patch
x86-uv-update-xpc-to-handle-updated-bios-interface.patch
x86-uv-xpc-null-deref-when-mesq-becomes-empty.patch
x86-uv-xpc_make_first_contact-hang-due-to-not-accepting-active-state.patch
x86-uv-xpc-receive-message-reuse-triggers-invalid-bug_on.patch
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