On 01.07.20 17:38, Luis Chamberlain wrote:

On Wed, Jul 01, 2020 at 11:08:57PM +0900, Tetsuo Handa wrote:

quoted

On 2020/07/01 22:53, Luis Chamberlain wrote:

quoted

quoted

Well, it is not br_stp_call_user() but br_stp_start() which is expecting
to set sub_info->retval for both KWIFEXITED() case and KWIFSIGNALED() case.
That is, sub_info->retval needs to carry raw value (i.e. without "umh: fix
processed error when UMH_WAIT_PROC is used" will be the correct behavior).

br_stp_start() doesn't check for the raw value, it just checks for err
or !err. So the patch, "umh: fix processed error when UMH_WAIT_PROC is
used" propagates the correct error now.

No. If "/sbin/bridge-stp virbr0 start" terminated due to e.g. SIGSEGV
(for example, by inserting "kill -SEGV $$" into right after "#!/bin/sh" line),
br_stp_start() needs to select BR_KERNEL_STP path. We can't assume that
/sbin/bridge-stp is always terminated by exit() syscall (and hence we can't
ignore KWIFSIGNALED() case in call_usermodehelper_exec_sync()).

Ah, well that would be a different fix required, becuase again,
br_stp_start() does not untangle the correct error today really.
I also I think it would be odd odd that SIGSEGV or another signal 
is what was terminating Christian's bridge stp call, but let's
find out!

Note we pass 0 to the options to wait so the mistake here could indeed
be that we did not need KWIFSIGNALED(). I was afraid of this prospect...
as it other implications.

It means we either *open code* all callers, or we handle this in a
unified way on the umh. And if we do handle this in a unified way, it
then begs the question as to *what* do we pass for the signals case and
continued case. Below we just pass the signal, and treat continued as
OK, but treating continued as OK would also be a *new* change as well.

For instance (this goes just boot tested, but Christian if you can
try this as well that would be appreciated):

Does not help, the bridge stays in DOWN state.