[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <87wntc1zee.fsf@oldenburg.str.redhat.com>
Date: Thu, 08 Apr 2021 19:04:09 +0200
From: Florian Weimer <fweimer@...hat.com>
To: "Andrey Bugaevskiy" <bugaevskiy@...dex-team.ru>
Cc: <musl@...ts.openwall.com>
Subject: Re: errno and swapcontext in a multithreaded setup
* Andrey Bugaevskiy:
> I'm using makecontext/swapcontext to migrate contexts between threads
> and this sometimes leads to getting incorrect errno values.
>
> Investigating further I've noticed that __errno_location
> is marked __attribute__((const)).
> This causes optimizers to assume that errno address never changes
> in the scope of the function which is not the case in my scenario.
The optimizers make the same assumption for actual thread-local
variables, not just __errno_location. Migrating contexts between
threads results in undefined behavior.
Thanks,
Florian
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
