Date: Tue, 11 Aug 2020 14:31:26 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: Emmanuel Vadot <manu@bidouilliste.com> Cc: Alan Cox <alc@rice.edu>, Emmanuel Vadot <manu@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r363842 - head/sys/compat/linuxkpi/common/include/linux Message-ID: <CAGudoHHJ7mj3td4jD2SNABANoAsSwzKrOM18WE-zhoV0sNWbiQ@mail.gmail.com> In-Reply-To: <20200804202541.0b6b3eb6ce26522ee12a796c@bidouilliste.com> References: <202008041525.074FPNLh043749@repo.freebsd.org> <1c90911b-d5f6-f8b1-8f4d-97a88fa028bd@rice.edu> <20200804202541.0b6b3eb6ce26522ee12a796c@bidouilliste.com>
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Hi. This remains unfixed. On 8/4/20, Emmanuel Vadot <manu@bidouilliste.com> wrote: > On Tue, 4 Aug 2020 13:11:02 -0500 > Alan Cox <alc@rice.edu> wrote: > >> >> On 8/4/20 10:25 AM, Emmanuel Vadot wrote: >> > Author: manu >> > Date: Tue Aug 4 15:25:22 2020 >> > New Revision: 363842 >> > URL: https://svnweb.freebsd.org/changeset/base/363842 >> > >> > Log: >> > linuxkpi: Add clear_bit_unlock >> > >> > This calls clear_bit and adds a memory barrier. >> > >> > Sponsored by: The FreeBSD Foundation >> > >> > Reviewed by: hselasky >> > MFC after: 1 week >> > Differential Revision: https://reviews.freebsd.org/D25943 >> > >> > Modified: >> > head/sys/compat/linuxkpi/common/include/linux/bitops.h >> > >> > Modified: head/sys/compat/linuxkpi/common/include/linux/bitops.h >> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D >> > --- head/sys/compat/linuxkpi/common/include/linux/bitops.h Tue Aug 4 >> > 15:00:02 2020 (r363841) >> > +++ head/sys/compat/linuxkpi/common/include/linux/bitops.h Tue Aug 4 >> > 15:25:22 2020 (r363842) >> > @@ -275,6 +275,13 @@ find_next_zero_bit(const unsigned long *addr, >> > unsigned >> > #define test_bit(i, a) \ >> > !!(READ_ONCE(((volatile const unsigned long *)(a))[BIT_WORD(i)])= & >> > BIT_MASK(i)) >> > >> > +static inline void >> > +clear_bit_unlock(long bit, volatile unsigned long *var) >> > +{ >> > + clear_bit(bit, var); >> > + wmb(); >> >> >> For an unlock operation, the memory barrier should come before the >> clear_bit() call, not after.=C2=A0 See, for example, the alpha implement= ation >> in Linux.=C2=A0 Also, the correct "spelling" for this memory barrier in >> FreeBSD would be atomic_thread_fence_rel(). See, for example, the >> comment at the top of sys/amd64/include/atomic.h. > > Ah yes, thanks. I probably got lost looking for the linux implem but > that does make sense, I'll fix that probably tomorow. > > Thanks. > >> >> > +} >> > + >> > static inline int >> > test_and_clear_bit(long bit, volatile unsigned long *var) >> > { > > > -- > Emmanuel Vadot <manu@bidouilliste.com> <manu@freebsd.org> > --=20 Mateusz Guzik <mjguzik gmail.com>
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