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From: Florian Weimer <fweimer@redhat.com>
To: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Adhemerval Zanella Netto via Libc-help <libc-help@sourceware.org>,
	 Rain <glibc@sunshowers.io>
Subject: Re: posix_spawn: parent can get stuck in uninterruptible sleep if child receives SIGTSTP early enough
Date: Tue, 13 Sep 2022 12:04:10 +0200	[thread overview]
Message-ID: <877d27vbdx.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <7c356365-34db-cc00-bb92-0e55e7a89118@linaro.org> (Adhemerval Zanella Netto's message of "Mon, 22 Aug 2022 15:32:47 -0300")

* Adhemerval Zanella Netto:

> On 22/08/22 15:21, Florian Weimer wrote:
>> * Adhemerval Zanella Netto via Libc-help:
>> 
>>> Right, my mistake.  I understood the issue better now, although I am
>>> still puzzled why SIGTSTP is only being triggered on sigprocmask (sing
>>> default action is still to stop PROCESS).
>> 
>> I think it's a maskable stop, not an unmaskable one, like SIGSTOP.
>
> Yeah, we do block the signal on parent (internal_signal_block_all). 
>
>> 
>> This looks a vfork-specific bug that can't happen with fork.  I don't
>> see how to fix it in a generic fashion because we can't unblock SIGTSTP
>> and launch the new process in an atomic fashion.
>
> We might ask for a new clone3 field to define the default signal mask on 
> process start (and thus omit the final sigprocmask before execve).

It might already possible to fix this using io_uring.  Unfortunately, I
didn't attend the LPC presentation.

Thanks,
Florian


  parent reply	other threads:[~2022-09-13 10:04 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-14  3:30 Rain
2022-08-14  3:38 ` Rain
2022-08-22 16:51 ` Adhemerval Zanella Netto
2022-08-22 17:00   ` Rain
2022-08-22 17:48     ` Adhemerval Zanella Netto
2022-08-22 18:21       ` Florian Weimer
2022-08-22 18:32         ` Adhemerval Zanella Netto
2022-08-22 22:28           ` Adhemerval Zanella Netto
2022-09-13 10:04           ` Florian Weimer [this message]
2022-09-21 15:24             ` Adhemerval Zanella Netto
2022-09-22 12:18               ` Florian Weimer
2022-09-22 16:56                 ` Adhemerval Zanella Netto
2022-09-22 17:38                   ` Florian Weimer
2022-09-22 19:14                     ` Adhemerval Zanella Netto
2022-10-10 13:45                       ` Florian Weimer
2022-10-18 20:04                         ` Adhemerval Zanella Netto
2022-10-20 11:55                           ` Florian Weimer
2022-10-21  1:40                             ` Rain
2022-10-21 14:18                               ` Szabolcs Nagy
2022-08-22 22:30       ` Adhemerval Zanella Netto

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