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[66.111.4.227]) by smtp.gmail.com with ESMTPSA id i10sm200482ilv.86.2022.02.03.16.20.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Feb 2022 16:20:33 -0800 (PST) Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailauth.nyi.internal (Postfix) with ESMTP id 20C5F27C0054; Thu, 3 Feb 2022 19:20:31 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute5.internal (MEProxy); Thu, 03 Feb 2022 19:20:32 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvvddrgeekgddvudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpeffhffvuffkfhggtggujgesghdtreertddtvdenucfhrhhomhepuehoqhhunhcu hfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrghtth gvrhhnpeehfedujeeuffejleektdegleellefgfffhhfdvhedtkeevheejiedvjeeguddu geenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegsoh hquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtdeigedq udejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehfihigmh gvrdhnrghmvg X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 3 Feb 2022 19:20:30 -0500 (EST) Date: Fri, 4 Feb 2022 08:20:25 +0800 From: Boqun Feng To: Mark Rutland Cc: linux-kernel@vger.kernel.org, ardb@kernel.org, arnd@arndb.de, peterz@infradead.org, will@kernel.org Subject: Re: [PATCH v2] atomics: fix atomic64_{read_acquire,set_release} fallbacks Message-ID: References: <20220203161243.3955547-1-mark.rutland@arm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="DeK3NdMhXyr5ss/7" Content-Disposition: inline In-Reply-To: <20220203161243.3955547-1-mark.rutland@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --DeK3NdMhXyr5ss/7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Feb 03, 2022 at 04:12:43PM +0000, Mark Rutland wrote: > diff --git a/include/linux/atomic/atomic-arch-fallback.h b/include/linux/= atomic/atomic-arch-fallback.h > index a3dba31df01e..6db58d180866 100644 > --- a/include/linux/atomic/atomic-arch-fallback.h > +++ b/include/linux/atomic/atomic-arch-fallback.h > @@ -151,7 +151,16 @@ > static __always_inline int > arch_atomic_read_acquire(const atomic_t *v) > { > - return smp_load_acquire(&(v)->counter); > + int ret; > + > + if (__native_word(atomic_t)) { > + ret =3D smp_load_acquire(&(v)->counter); > + } else { > + ret =3D arch_atomic_read(v); > + __atomic_acquire_fence(); > + } > + > + return ret; > } > #define arch_atomic_read_acquire arch_atomic_read_acquire > #endif > @@ -160,7 +169,12 @@ arch_atomic_read_acquire(const atomic_t *v) > static __always_inline void > arch_atomic_set_release(atomic_t *v, int i) > { > - smp_store_release(&(v)->counter, i); > + if (__native_word(atomic_t)) { > + smp_store_release(&(v)->counter, i); > + } else { > + __atomic_release_fence(); > + arch_atomic_set(v, i); > + } > } The changes for atomic_t are not necessary, right? They are correct but "side effects" because of the change in scripts. If so, it's better to mention this somewhere. Regards, Boqun > #define arch_atomic_set_release arch_atomic_set_release > #endif > @@ -1258,7 +1272,16 @@ arch_atomic_dec_if_positive(atomic_t *v) > static __always_inline s64 > arch_atomic64_read_acquire(const atomic64_t *v) > { > - return smp_load_acquire(&(v)->counter); > + s64 ret; > + > + if (__native_word(atomic64_t)) { > + ret =3D smp_load_acquire(&(v)->counter); > + } else { > + ret =3D arch_atomic64_read(v); > + __atomic_acquire_fence(); > + } > + > + return ret; > } > #define arch_atomic64_read_acquire arch_atomic64_read_acquire > #endif > @@ -1267,7 +1290,12 @@ arch_atomic64_read_acquire(const atomic64_t *v) > static __always_inline void > arch_atomic64_set_release(atomic64_t *v, s64 i) > { > - smp_store_release(&(v)->counter, i); > + if (__native_word(atomic64_t)) { > + smp_store_release(&(v)->counter, i); > + } else { > + __atomic_release_fence(); > + arch_atomic64_set(v, i); > + } > } > #define arch_atomic64_set_release arch_atomic64_set_release > #endif > @@ -2358,4 +2386,4 @@ arch_atomic64_dec_if_positive(atomic64_t *v) > #endif > =20 > #endif /* _LINUX_ATOMIC_FALLBACK_H */ > -// cca554917d7ea73d5e3e7397dd70c484cad9b2c4 > +// 8e2cc06bc0d2c0967d2f8424762bd48555ee40ae > diff --git a/scripts/atomic/fallbacks/read_acquire b/scripts/atomic/fallb= acks/read_acquire > index 803ba7561076..a0ea1d26e6b2 100755 > --- a/scripts/atomic/fallbacks/read_acquire > +++ b/scripts/atomic/fallbacks/read_acquire > @@ -2,6 +2,15 @@ cat < static __always_inline ${ret} > arch_${atomic}_read_acquire(const ${atomic}_t *v) > { > - return smp_load_acquire(&(v)->counter); > + ${int} ret; > + > + if (__native_word(${atomic}_t)) { > + ret =3D smp_load_acquire(&(v)->counter); > + } else { > + ret =3D arch_${atomic}_read(v); > + __atomic_acquire_fence(); > + } > + > + return ret; > } > EOF > diff --git a/scripts/atomic/fallbacks/set_release b/scripts/atomic/fallba= cks/set_release > index 86ede759f24e..05cdb7f42477 100755 > --- a/scripts/atomic/fallbacks/set_release > +++ b/scripts/atomic/fallbacks/set_release > @@ -2,6 +2,11 @@ cat < static __always_inline void > arch_${atomic}_set_release(${atomic}_t *v, ${int} i) > { > - smp_store_release(&(v)->counter, i); > + if (__native_word(${atomic}_t)) { > + smp_store_release(&(v)->counter, i); > + } else { > + __atomic_release_fence(); > + arch_${atomic}_set(v, i); > + } > } > EOF > --=20 > 2.30.2 >=20 --DeK3NdMhXyr5ss/7 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEj5IosQTPz8XU1wRHSXnow7UH+rgFAmH8cUQACgkQSXnow7UH +rhBYwf+KigCllStLyqJn7racO6pAE6IUw2TuK3BtBiUtXbE7C+BBVoxwfv/HPMs RQ8fNJp/XcXNLqgsZ5uMNnVHaOPXr1lh5c7fnWXSGTgFuJqinAsclc1hcEzSHoIk 8drywpQlVZoqF5bauSHBp4tYUk2D9jomMU6eFu+sRlHdugTpUXJFR/r64Xn3ja/I TtlGpICkPalaU5ROqKGJLz0eVm6JxYoAUl4uBnctQ45XkJbojMyib1ARWWBdG+dR RDHnx1IM9Z12OLbEnFNtDoHLsAwEiA8e+UmJmcPiF47SdsJ7eaVqEPWGgcxX9i80 a3zJXpYLg7TeBiiqQabYboV2zx9r9w== =KBIG -----END PGP SIGNATURE----- --DeK3NdMhXyr5ss/7--