From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Florian Weimer <fweimer@redhat.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH 3/3] Refactor atfork handlers
Date: Tue, 20 Feb 2018 13:58:00 -0000 [thread overview]
Message-ID: <2fc18517-d23d-a298-e458-88ceff1cfc33@linaro.org> (raw)
In-Reply-To: <fb02baf9-fcae-c224-4ae0-7a7857b7d8fc@redhat.com>
On 20/02/2018 10:42, Florian Weimer wrote:
> On 02/20/2018 02:27 PM, Adhemerval Zanella wrote:
>> I think it might occur with proposed implementation only if a callback tries to call
>> pthread_atfork or fork itself. It these scenario you have in mind? And should we
>> really support them if this is the case?
>
> No.
>
> __libc_fork starts like this:
>
> Â bool multiple_threads
> Â Â Â = THREAD_GETMEM (THREAD_SELF, header.multiple_threads);
>
> Â __run_fork_handlers (atfork_run_prepare);
>
> And then acquires _IO_list_lock.
>
> I don't see anything which prevents concurrent registration of additional fork handlers between the first and second call to __run_fork_handlers.
The atfork_run_prepare will instruct __run_fork_handlers to take the internal
atfork_lock handler:
void
__run_fork_handlers (enum __run_fork_handler_type who)
{
struct fork_handler *runp;
if (who == atfork_run_prepare)
{
lll_lock (atfork_lock, LLL_PRIVATE);
And it will prevent to add new registration until either the parent or the child
call __run_fork_handlers with either 'atfork_run_child' or 'atfork_run_parent'
to release the lock.
>
> As I said, that shouldn't prevent inclusion of the current patch, but we need to fix this before 2.28, I think.
>
> Thanks,
> Florian
next prev parent reply other threads:[~2018-02-20 13:48 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-07 14:10 [PATCH 1/3] Refactor Linux ARCH_FORK implementation Adhemerval Zanella
2018-02-07 13:09 ` [PATCH 3/3] Refactor atfork handlers Adhemerval Zanella
2018-02-07 15:13 ` Florian Weimer
2018-02-07 17:38 ` Adhemerval Zanella
2018-02-08 11:26 ` Florian Weimer
2018-02-08 13:49 ` Adhemerval Zanella
2018-02-20 12:57 ` Florian Weimer
2018-02-20 13:26 ` Adhemerval Zanella
2018-02-20 13:27 ` Florian Weimer
2018-02-20 13:30 ` Adhemerval Zanella
2018-02-20 13:48 ` Florian Weimer
2018-02-20 13:58 ` Adhemerval Zanella [this message]
2018-02-20 13:59 ` Florian Weimer
2018-02-20 17:22 ` Adhemerval Zanella
2018-02-23 12:17 ` Florian Weimer
2018-02-23 17:42 ` Adhemerval Zanella
2018-02-27 12:03 ` Florian Weimer
2018-02-07 13:35 ` [PATCH 2/3] dynarray: Implement remove function Adhemerval Zanella
2018-02-07 15:07 ` Alexander Monakov
2018-02-07 17:16 ` Adhemerval Zanella
2018-03-07 16:51 ` [PATCH 1/3] Refactor Linux ARCH_FORK implementation Adhemerval Zanella
2018-03-08 12:05 ` Florian Weimer
2018-03-08 12:58 ` Adhemerval Zanella
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