From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Florian Weimer <fweimer@redhat.com>,
Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [PATCH v2 2/9] nptl: Deallocate the thread stack on setup failure (BZ #19511)
Date: Tue, 1 Jun 2021 10:08:15 -0300 [thread overview]
Message-ID: <69aac17c-75e1-5b80-7df7-1dc09dea18b4@linaro.org> (raw)
In-Reply-To: <87r1hm6l4g.fsf@oldenburg.str.redhat.com>
On 01/06/2021 05:32, Florian Weimer wrote:
> * Adhemerval Zanella via Libc-alpha:
>
>> @@ -424,17 +409,22 @@ start_thread (void *arg)
>> have ownership (see CONCURRENCY NOTES above). */
>> if (__glibc_unlikely (pd->stopped_start))
>> {
>> /* Get the lock the parent locked to force synchronization. */
>> lll_lock (pd->lock, LLL_PRIVATE);
>>
>> /* We have ownership of PD now. */
>> + if (pd->setup_failed == 1)
>> + {
>> + /* In the case of a failed setup, the created thread will be
>> + responsible to free up the allocated resources. The
>> + detached mode ensure it won't be joined and it will trigger
>> + the required cleanup. */
>> + pd->joinid = pd;
>> + __do_cancel ();
>> + }
>>
>> /* And give it up right away. */
>> lll_unlock (pd->lock, LLL_PRIVATE);
>> }
>
> I don't think this is quite right. The failed thread should not linger
> around after pthread_create has reported failure to the caller. It's
> better than what we had before, so maybe we should use this version and
> clean it up further later.
Agreed, but I think this is really an improvement over current strategy
as I commented earlier [1]. I think to proper fix would move the
lock prior any initialization so we don't need to run any unwinding
operations, skip directly to INTERNAL_SYSCALL_CALL (exit, 0), and let the
parent join the thread and do the resource deallocation.
>
> At the point of the __do_cancel call, unwinding may not yet initialized,
> so the implied dlopen happens on a potentially very small stack. It
> should be possible to replace it with a goto to the cleanup code. Or
> maybe put the cleanup code into a separate function and call it here and
> on the regular cleanup path.
>
> Apart from that, it looks fine to me.
The __do_cancel is not done really in asynchronous mode, so it will use
the allocated thread stack for the dlopen. But I think with a better
strategy to move the 'struct thread' lock earlier than any initialization
will avoid such issue.
>
> Thanks,
> Florian
>
[1] https://sourceware.org/pipermail/libc-alpha/2021-May/126879.html
next prev parent reply other threads:[~2021-06-01 13:08 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-27 17:28 [PATCH v2 0/9] nptl: pthread cancellation refactor Adhemerval Zanella
2021-05-27 17:28 ` [PATCH v2 1/9] nptl: Remove exit-thread.h Adhemerval Zanella
2021-06-01 7:51 ` Florian Weimer
2021-06-01 12:55 ` Adhemerval Zanella
2021-05-27 17:28 ` [PATCH v2 2/9] nptl: Deallocate the thread stack on setup failure (BZ #19511) Adhemerval Zanella
2021-06-01 8:32 ` Florian Weimer
2021-06-01 13:08 ` Adhemerval Zanella [this message]
2021-06-01 13:55 ` Adhemerval Zanella
2021-06-02 12:56 ` [PATCH v3] " Adhemerval Zanella
2021-06-02 13:08 ` Andreas Schwab
2021-06-02 13:39 ` Adhemerval Zanella
2021-06-02 13:41 ` Andreas Schwab
2021-06-02 14:01 ` Adhemerval Zanella
2021-06-02 14:07 ` Andreas Schwab
2021-06-02 14:15 ` Adhemerval Zanella
2021-06-02 14:30 ` Andreas Schwab
2021-06-02 14:42 ` Adhemerval Zanella
2021-06-02 18:20 ` Joseph Myers
2021-06-02 18:30 ` Florian Weimer
2021-06-02 19:02 ` Adhemerval Zanella
2021-06-02 19:11 ` Florian Weimer
2021-06-08 10:56 ` Florian Weimer
2021-06-08 17:01 ` Adhemerval Zanella
2021-06-09 13:49 ` Florian Weimer
2021-06-09 17:07 ` Adhemerval Zanella
2021-05-27 17:28 ` [PATCH v2 3/9] nptl: Install cancellation handler on pthread_cancel Adhemerval Zanella
2021-05-31 18:18 ` Adhemerval Zanella
2021-06-01 8:38 ` Florian Weimer
2021-06-01 13:10 ` Adhemerval Zanella
2021-06-01 8:39 ` Florian Weimer
2021-05-27 17:28 ` [PATCH v2 4/9] nptl: Remove CANCELING_BITMASK Adhemerval Zanella
2021-06-01 9:03 ` Florian Weimer
2021-06-01 13:50 ` Adhemerval Zanella
2021-06-01 16:36 ` Adhemerval Zanella
2021-05-27 17:28 ` [PATCH v2 5/9] nptl: Move cancel state out of cancelhandling Adhemerval Zanella
2021-06-01 9:58 ` Florian Weimer
2021-06-02 13:09 ` Adhemerval Zanella
2021-05-27 17:28 ` [PATCH v2 6/9] nptl: Move cancel type " Adhemerval Zanella
2021-06-01 12:37 ` Florian Weimer
2021-06-02 13:11 ` Adhemerval Zanella
2021-06-09 17:06 ` Adhemerval Zanella
2021-05-27 17:28 ` [PATCH v2 7/9] nptl: Implement raise in terms of pthread_kill Adhemerval Zanella
2021-06-01 12:40 ` Florian Weimer
2021-06-02 13:14 ` Adhemerval Zanella
2021-05-27 17:28 ` [PATCH v2 8/9] nptl: Use pthread_kill on pthread_cancel Adhemerval Zanella
2021-06-01 12:41 ` Florian Weimer
2021-05-27 17:28 ` [PATCH v2 9/9] nptl: Avoid async cancellation to wrongly update __nptl_nthreads (BZ #19366) Adhemerval Zanella
2021-06-01 14:29 ` Florian Weimer
2021-06-02 13:15 ` Adhemerval Zanella
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