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Date:      Thu, 09 Mar 2017 10:59:27 +0100
From:      Alexandre Martins <alexandre.martins@stormshield.eu>
To:        freebsd-current <freebsd-current@freebsd.org>
Subject:   Re: smp_rendezvous_action: Are atomics correctly used ?
Message-ID:  <4355496.HzrDjoMEL6@pc-alex>
In-Reply-To: <2092905.6A8RAGlt18@pc-alex>
References:  <2092905.6A8RAGlt18@pc-alex>

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I have the save question for the cpu_ipi_pending here:

https://svnweb.freebsd.org/base/head/sys/x86/x86/mp_x86.c?view=3Dannota=
te#l1080

Le jeudi 9 mars 2017, 10:43:14 Alexandre Martins a =E9crit :
> Hello,
>=20
> I'm curently reading the code of the function smp_rendezvous_action, =
in
> kern/subr_smp.c file. In that function, i see that the variable
> smp_rv_waiters is read in some while() loop in a non-atomic way.
>=20
> https://svnweb.freebsd.org/base/head/sys/kern/subr_smp.c?view=3Dannot=
ate#l412
> https://svnweb.freebsd.org/base/head/sys/kern/subr_smp.c?view=3Dannot=
ate#l458
> https://svnweb.freebsd.org/base/head/sys/kern/subr_smp.c?view=3Dannot=
ate#l472
>=20
> I suspect one of my freeze to be due by that.
>=20
> Should this function be patched to use
> "atomic_load_acq_int(&smp_rv_waiters[])" ?
>=20
> Best regards

=2D-=20
Alexandre Martins
STORMSHIELD


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