On 12/18/18 3:23 PM, Eric Blake wrote:
On 11/2/18 10:11 AM, Vladimir Sementsov-Ogievskiy wrote:
Reduce extra noise of nbd-client, change 083 correspondingly.
This says what, but not why. The details from the cover letter are
important to include here, namely:
It was discussed, that error messages, produced by error_reprt_err's,
added in f140e300 are
1. not really needed
2. subject to race conditions
And it was decided to drop them (switch to trace-points), look thread
https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg00833.html
So, I've also dropped error_report_err, added earlier in be41c100c0d
and later in 78a33ab5878.
@@ -79,7 +81,9 @@ static coroutine_fn void nbd_read_reply_entry(void
*opaque)
assert(s->reply.handle == 0);
ret = nbd_receive_reply(s->ioc, &s->reply, &local_err);
if (local_err) {
- error_report_err(local_err);
+ trace_nbd_read_reply_entry_fail(ret,
error_get_pretty(local_err),
+ error_get_hint(local_err)
?: "");
I'm not sold on the error hint being useful in the trace message. For
that matter, even error_get_pretty() seems like it might be rather verbose.
I do see why you are trying it, though: in nbd/client.c,
nbd_handle_reply_err(), we have:
Actually, on looking further, the ONLY use of error_append_hint() in
nbd/client.c is when handling NBD_OPT_ which is synchronous when first
establishing the connection; but all of the additions of trace_nbd_*
calls in this file occur during transmission phase, where we don't have
any hints appended. I could NOT trigger any error path where a hint
would be present in the first place (although I will admit that I may
have missed a spot in my tracing).
But instead of trying to make all the tracepoints in block/nbd-client.c
extract this information, we could just improve nbd/client.c to have a
tracepoint for any server-received error message at the same point where
it calls error_append_hint().
This part is still true, even if it is no longer relevant to this patch.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
