Messages in this thread | | | Date | Thu, 26 Sep 2013 21:10:34 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] tty: Fix SIGTTOU not sent with tcflush() |
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On 09/26, Oleg Nesterov wrote: > > Thanks Peter. > > Well. I'am afraid my testing was wrong, because Karel reports > it fixes the problem... > > But. I applied this patch to my 3.11 tree (last commit is bff157b3a) > which also has the additional patch (03e12617 "tty: disassociate_ctty() > sends the extra SIGCONT"), and > > TET_CONFIG=CFG TET_ROOT=. ./T.tcflush 4 > > still fails... T.tcflush was compiled on another (Karel's) machine, > perhaps there is something in libc, I do not know. > > So let me ask just in case, I assume the fix below doesn't depend on > other changes I could miss? > > I'll retest after git-pull and report...
Still fails under the Linus's tree + this patch.
However!!!
Tested-by: Oleg Nesterov <oleg@redhat.com>
It turns out, T.tcflush doesn't expect it can start as a process group leader. In this case setsid() fails, then tty_open() doesn't set signal->tty, and thus this patch makes no difference: tty_check_change() fails because tty doesn't match signal->tty.
And indeed, this test passes if you run it under strace, or simply do
$ TET_CONFIG=CFG TET_ROOT=. perl -e "system './T.tcflush 4'"
And damn, the fact it doesn't fail under strace doesn't allow you to see that setsid() fails ;)
This is probably explains why Karel reported success, perhaps he didn't run this test individually.
Thanks again Peter. Perhaps my analysis was wrong (and I do not see setsid() in the sources), I do not really care. but perhaps tcflush.c should be updated.
Oleg.
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