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bug#36609: 27.0.50; Possible race-condition in threading implementation
From: |
dick . r . chiang |
Subject: |
bug#36609: 27.0.50; Possible race-condition in threading implementation |
Date: |
Sun, 20 Jun 2021 10:01:37 -0400 |
User-agent: |
Gnus/5.14 (Gnus v5.14pre) Emacs/28.0.50 (gnu/linux) |
Yes! If you just add a negation to the __atomic_sub_fetch call, this passes
all the MREs.
It's not clear how you want to deal with the #else GNUC_PREREQ (4, 7, 0).
>>>>> "EZ" == Eli Zaretskii <eliz@gnu.org> writes:
>> From: dick.r.chiang@gmail.com
>> Cc: 36609@debbugs.gnu.org
>> Date: Sat, 19 Jun 2021 17:12:32 -0400
>>
>> "Suggest" or "Provide"?
>>
>> If the former, well, my recalcitrance should be your answer.
>>
>> If the latter, sure
EZ> Thanks, please try the patch below.
>> although if you've written the patch, then running my MREs would be epsilon
>> more effort.
EZ> You have a use case and wrote code with which you are familiar, so you are
EZ> in a better position to test it. Moreover, I don't have access to a
EZ> system where these problems could happen, so it's far from epsilon effort
EZ> for me.
EZ> diff --git a/src/xgselect.c b/src/xgselect.c
EZ> index 0d91d55bad..9a90670b0f 100644
EZ> --- a/src/xgselect.c
EZ> +++ b/src/xgselect.c
EZ> @@ -34,12 +34,27 @@ static GMainContext *glib_main_context;
EZ> void release_select_lock (void)
EZ> {
EZ> +#if GNUC_PREREQ (4, 7, 0)
EZ> + if (__atomic_sub_fetch (&threads_holding_glib_lock, 1, __ATOMIC_ACQ_REL))
EZ> + g_main_context_release (glib_main_context);
EZ> +#else
EZ> if (--threads_holding_glib_lock == 0)
EZ> g_main_context_release (glib_main_context);
EZ> +#endif
EZ> }
EZ> static void acquire_select_lock (GMainContext *context)
EZ> {
EZ> +#if GNUC_PREREQ (4, 7, 0)
EZ> + if (__atomic_fetch_add (&threads_holding_glib_lock, 1, __ATOMIC_ACQ_REL)
== 0)
EZ> + {
EZ> + glib_main_context = context;
EZ> + while (!g_main_context_acquire (context))
EZ> + {
EZ> + /* Spin. */
EZ> + }
EZ> + }
EZ> +#else
EZ> if (threads_holding_glib_lock++ == 0)
EZ> {
EZ> glib_main_context = context;
EZ> @@ -48,6 +63,7 @@ static void acquire_select_lock (GMainContext *context)
EZ> /* Spin. */
EZ> }
EZ> }
EZ> +#endif
EZ> }
EZ> /* `xg_select' is a `pselect' replacement. Why do we need a separate
EZ> function?
- bug#36609: 27.0.50; Possible race-condition in threading implementation, (continued)
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/10
- bug#36609: 27.0.50; Possible race-condition in threading implementation, dick . r . chiang, 2021/06/10
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/10
- bug#36609: 27.0.50; Possible race-condition in threading implementation, dick . r . chiang, 2021/06/10
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/11
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/19
- bug#36609: 27.0.50; Possible race-condition in threading implementation, dick . r . chiang, 2021/06/19
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/19
- bug#36609: 27.0.50; Possible race-condition in threading implementation, dick . r . chiang, 2021/06/19
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/20
- bug#36609: 27.0.50; Possible race-condition in threading implementation,
dick . r . chiang <=
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/20
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/25
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Andreas Schwab, 2021/06/10
- bug#36609: 27.0.50; Possible race-condition in threading implementation, Eli Zaretskii, 2021/06/10