From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CE47B149C51 for ; Fri, 6 Dec 2024 15:27:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733498848; cv=none; b=ijs7dp5tDIs72Rq5vClXl2c1xpoGRa4GmAWftkl/7Jwx681eNO9i0rVCahxtxJoiUg6VOD0PBnZP/LDWiazYK80Wc86TPXCNneBivmo1uUACXMus7NlKxkibpVmrc4B86CYMeJtGPm6EHp/DMBpd3OUZNUtQekVkx1paIL8OGTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733498848; c=relaxed/simple; bh=kSe4+Fu7Fk9MRHJRR49GUnNDghbh8RXO5rxjW/94urI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=J8wfkJ0AspffUo6nuu0nlUFNfXauOEM+4brDOZ1URVA34RzLCeLn47eSn+YEHy1trM148rqkxgC5WGsizzj5xJ2wC1zIIMAqtUUf/5o90OAG82KNOsXub8OQmi9en5LjkUDVuuwRRtJN/7iOIIZFvixXuvI+ukW+cv83f53IuWU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sqsGi8Ym; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sqsGi8Ym" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3CB3C4CEDC; Fri, 6 Dec 2024 15:27:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733498848; bh=kSe4+Fu7Fk9MRHJRR49GUnNDghbh8RXO5rxjW/94urI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=sqsGi8YmH4PDQkSxQSRCU89QcZU4FjIusGFeCUkY/de827zRfRQniCxHn4TWvxVQw 7xR5hzHdtqaXt5kzv0/CWRJLGjmvKf0CLdweZUPVql+r8igTmHuK7bfXgo4SY1UKWF 2K4+TNCD9RTS7NlIXfBD7NGFnjd0HjIhAjHr1A4A5OUwgCHmCEh/NiNHOvLk7vlkOa 8rnN+QCxXqijiwQpBOBcZBSeknV6p0pVhTcOeRJQ4SUn9bWVCcFbVBanDw4WEEvSF1 YgaFU0pWJ/oS3J8KNV1chLYTnHA8D69x4wZlVqLN/Y5DvwuzpJ4UtSy33/fmfyFcRw fy6r3jbj+2KBg== Message-ID: <89ecea41c8d4aa9ce33468c449f76e0ffc0286a2.camel@kernel.org> Subject: Re: [PATCH 1/2] nfsd: use new wake_up_var interfaces. From: Jeff Layton To: NeilBrown Cc: Chuck Lever , linux-nfs@vger.kernel.org, Olga Kornievskaia , Dai Ngo , Tom Talpey Date: Fri, 06 Dec 2024 10:27:26 -0500 In-Reply-To: <173346540850.1734440.373396718120959851@noble.neil.brown.name> References: <>, <36a543b848e59ddf26c85d0c79b7e377d865a0af.camel@kernel.org> <173346540850.1734440.373396718120959851@noble.neil.brown.name> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn VluJH0/RcxEeFbnSaswVChNSGa7mXJrTR22lRL6ZPjdMgS2Km90haWPRc8Wolcz07Y2se0xpGVLEQ cDEsvv5IMmeMe1/qLZ6NaVkNuL3WOXvxaVT9USW1+/SGipO2IpKJjeDZfehlB/kpfF24+RrK+seQf CBYyUE8QJpvTZyfUHNYldXlrjO6n5MdOempLqWpfOmcGkwnyNRBR46g/jf8KnPRwXs509yAqDB6sE LZH+yWr9LQZEwARAQABtCVKZWZmIExheXRvbiA8amxheXRvbkBwb29jaGllcmVkcy5uZXQ+iQI7BB MBAgAlAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAUCTpXWPAIZAQAKCRAADmhBGVaCFc65D/4 gBLNMHopQYgG/9RIM3kgFCCQV0pLv0hcg1cjr+bPI5f1PzJoOVi9s0wBDHwp8+vtHgYhM54yt43uI 7Htij0RHFL5eFqoVT4TSfAg2qlvNemJEOY0e4daljjmZM7UtmpGs9NN0r9r50W82eb5Kw5bc/r0km R/arUS2st+ecRsCnwAOj6HiURwIgfDMHGPtSkoPpu3DDp/cjcYUg3HaOJuTjtGHFH963B+f+hyQ2B rQZBBE76ErgTDJ2Db9Ey0kw7VEZ4I2nnVUY9B5dE2pJFVO5HJBMp30fUGKvwaKqYCU2iAKxdmJXRI ONb7dSde8LqZahuunPDMZyMA5+mkQl7kpIpR6kVDIiqmxzRuPeiMP7O2FCUlS2DnJnRVrHmCljLkZ Wf7ZUA22wJpepBligemtSRSbqCyZ3B48zJ8g5B8xLEntPo/NknSJaYRvfEQqGxgk5kkNWMIMDkfQO lDSXZvoxqU9wFH/9jTv1/6p8dHeGM0BsbBLMqQaqnWiVt5mG92E1zkOW69LnoozE6Le+12DsNW7Rj iR5K+27MObjXEYIW7FIvNN/TQ6U1EOsdxwB8o//Yfc3p2QqPr5uS93SDDan5ehH59BnHpguTc27Xi QQZ9EGiieCUx6Zh2ze3X2UW9YNzE15uKwkkuEIj60NvQRmEDfweYfOfPVOueC+iFifbQgSmVmZiBM YXl0b24gPGpsYXl0b25AcmVkaGF0LmNvbT6JAjgEEwECACIFAk6V0q0CGwMGCwkIBwMCBhUIAgkKC wQWAgMBAh4BAheAAAoJEAAOaEEZVoIViKUQALpvsacTMWWOd7SlPFzIYy2/fjvKlfB/Xs4YdNcf9q LqF+lk2RBUHdR/dGwZpvw/OLmnZ8TryDo2zXVJNWEEUFNc7wQpl3i78r6UU/GUY/RQmOgPhs3epQC 3PMJj4xFx+VuVcf/MXgDDdBUHaCTT793hyBeDbQuciARDJAW24Q1RCmjcwWIV/pgrlFa4lAXsmhoa c8UPc82Ijrs6ivlTweFf16VBc4nSLX5FB3ls7S5noRhm5/Zsd4PGPgIHgCZcPgkAnU1S/A/rSqf3F LpU+CbVBDvlVAnOq9gfNF+QiTlOHdZVIe4gEYAU3CUjbleywQqV02BKxPVM0C5/oVjMVx3bri75n1 TkBYGmqAXy9usCkHIsG5CBHmphv9MHmqMZQVsxvCzfnI5IO1+7MoloeeW/lxuyd0pU88dZsV/riHw 87i2GJUJtVlMl5IGBNFpqoNUoqmvRfEMeXhy/kUX4Xc03I1coZIgmwLmCSXwx9MaCPFzV/dOOrju2 xjO+2sYyB5BNtxRqUEyXglpujFZqJxxau7E0eXoYgoY9gtFGsspzFkVNntamVXEWVVgzJJr/EWW0y +jNd54MfPRqH+eCGuqlnNLktSAVz1MvVRY1dxUltSlDZT7P2bUoMorIPu8p7ZCg9dyX1+9T6Muc5d Hxf/BBP/ir+3e8JTFQBFOiLNdFtB9KZWZmIExheXRvbiA8amxheXRvbkBzYW1iYS5vcmc+iQI4BBM BAgAiBQJOldK9AhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRAADmhBGVaCFWgWD/0ZRi4h N9FK2BdQs9RwNnFZUr7JidAWfCrs37XrA/56olQl3ojn0fQtrP4DbTmCuh0SfMijB24psy1GnkPep naQ6VRf7Dxg/Y8muZELSOtsv2CKt3/02J1BBitrkkqmHyni5fLLYYg6fub0T/8Kwo1qGPdu1hx2BQ RERYtQ/S5d/T0cACdlzi6w8rs5f09hU9Tu4qV1JLKmBTgUWKN969HPRkxiojLQziHVyM/weR5Reu6 FZVNuVBGqBD+sfk/c98VJHjsQhYJijcsmgMb1NohAzwrBKcSGKOWJToGEO/1RkIN8tqGnYNp2G+aR 685D0chgTl1WzPRM6mFG1+n2b2RR95DxumKVpwBwdLPoCkI24JkeDJ7lXSe3uFWISstFGt0HL8Eew P8RuGC8s5h7Ct91HMNQTbjgA+Vi1foWUVXpEintAKgoywaIDlJfTZIl6Ew8ETN/7DLy8bXYgq0Xzh aKg3CnOUuGQV5/nl4OAX/3jocT5Cz/OtAiNYj5mLPeL5z2ZszjoCAH6caqsF2oLyAnLqRgDgR+wTQ T6gMhr2IRsl+cp8gPHBwQ4uZMb+X00c/Amm9VfviT+BI7B66cnC7Zv6Gvmtu2rEjWDGWPqUgccB7h dMKnKDthkA227/82tYoFiFMb/NwtgGrn5n2vwJyKN6SEoygGrNt0SI84y6hEVbQlSmVmZiBMYXl0b 24gPGpsYXl0b25AcHJpbWFyeWRhdGEuY29tPokCOQQTAQIAIwUCU4xmKQIbAwcLCQgHAwIBBhUIAg kKCwQWAgMBAh4BAheAAAoJEAAOaEEZVoIV1H0P/j4OUTwFd7BBbpoSp695qb6HqCzWMuExsp8nZjr uymMaeZbGr3OWMNEXRI1FWNHMtcMHWLP/RaDqCJil28proO+PQ/yPhsr2QqJcW4nr91tBrv/MqItu AXLYlsgXqp4BxLP67bzRJ1Bd2x0bWXurpEXY//VBOLnODqThGEcL7jouwjmnRh9FTKZfBDpFRaEfD FOXIfAkMKBa/c9TQwRpx2DPsl3eFWVCNuNGKeGsirLqCxUg5kWTxEorROppz9oU4HPicL6rRH22Ce 6nOAON2vHvhkUuO3GbffhrcsPD4DaYup4ic+DxWm+DaSSRJ+e1yJvwi6NmQ9P9UAuLG93S2MdNNbo sZ9P8k2mTOVKMc+GooI9Ve/vH8unwitwo7ORMVXhJeU6Q0X7zf3SjwDq2lBhn1DSuTsn2DbsNTiDv qrAaCvbsTsw+SZRwF85eG67eAwouYk+dnKmp1q57LDKMyzysij2oDKbcBlwB/TeX16p8+LxECv51a sjS9TInnipssssUDrHIvoTTXWcz7Y5wIngxDFwT8rPY3EggzLGfK5Zx2Q5S/N0FfmADmKknG/D8qG IcJE574D956tiUDKN4I+/g125ORR1v7bP+OIaayAvq17RP+qcAqkxc0x8iCYVCYDouDyNvWPGRhbL UO7mlBpjW9jK9e2fvZY9iw3QzIPGKtClKZWZmIExheXRvbiA8amVmZi5sYXl0b25AcHJpbWFyeWRh dGEuY29tPokCOQQTAQIAIwUCU4xmUAIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEAAOa EEZVoIVzJoQALFCS6n/FHQS+hIzHIb56JbokhK0AFqoLVzLKzrnaeXhE5isWcVg0eoV2oTScIwUSU apy94if69tnUo4Q7YNt8/6yFM6hwZAxFjOXR0ciGE3Q+Z1zi49Ox51yjGMQGxlakV9ep4sV/d5a50 M+LFTmYSAFp6HY23JN9PkjVJC4PUv5DYRbOZ6Y1+TfXKBAewMVqtwT1Y+LPlfmI8dbbbuUX/kKZ5d dhV2736fgyfpslvJKYl0YifUOVy4D1G/oSycyHkJG78OvX4JKcf2kKzVvg7/Rnv+AueCfFQ6nGwPn 0P91I7TEOC4XfZ6a1K3uTp4fPPs1Wn75X7K8lzJP/p8lme40uqwAyBjk+IA5VGd+CVRiyJTpGZwA0 jwSYLyXboX+Dqm9pSYzmC9+/AE7lIgpWj+3iNisp1SWtHc4pdtQ5EU2SEz8yKvDbD0lNDbv4ljI7e flPsvN6vOrxz24mCliEco5DwhpaaSnzWnbAPXhQDWb/lUgs/JNk8dtwmvWnqCwRqElMLVisAbJmC0 BhZ/Ab4sph3EaiZfdXKhiQqSGdK4La3OTJOJYZphPdGgnkvDV9Pl1QZ0ijXQrVIy3zd6VCNaKYq7B AKidn5g/2Q8oio9Tf4XfdZ9dtwcB+bwDJFgvvDYaZ5bI3ln4V3EyW5i2NfXazz/GA/I/ZtbsigCFc 8ftCBKZWZmIExheXRvbiA8amxheXRvbkBrZXJuZWwub3JnPokCOAQTAQIAIgUCWe8u6AIbAwYLCQg HAwIGFQgCCQoLBBYCAwECHgECF4AACgkQAA5oQRlWghUuCg/+Lb/xGxZD2Q1oJVAE37uW308UpVSD 2tAMJUvFTdDbfe3zKlPDTuVsyNsALBGclPLagJ5ZTP+Vp2irAN9uwBuacBOTtmOdz4ZN2tdvNgozz uxp4CHBDVzAslUi2idy+xpsp47DWPxYFIRP3M8QG/aNW052LaPc0cedYxp8+9eiVUNpxF4SiU4i9J DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.4 (3.52.4-2.fc40) Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2024-12-06 at 17:10 +1100, NeilBrown wrote: > On Fri, 06 Dec 2024, Jeff Layton wrote: > > On Fri, 2024-12-06 at 13:55 +1100, NeilBrown wrote: > > > The wake_up_var interface is fragile as barriers are sometimes needed= . > > > There are now new interfaces so that most wake-ups can use an interfa= ce > > > that is guaranteed to have all barriers needed. > > >=20 > > > This patch changes the wake up on cl_cb_inflight to use > > > atomic_dec_and_wake_up(). > > >=20 > > > It also changes the wake up on rp_locked to use store_release_wake_up= (). > > > This involves changing rp_locked from atomic_t to int. > > >=20 > > > Signed-off-by: NeilBrown > > > --- > > > fs/nfsd/nfs4callback.c | 3 +-- > > > fs/nfsd/nfs4state.c | 16 ++++++---------- > > > fs/nfsd/state.h | 2 +- > > > 3 files changed, 8 insertions(+), 13 deletions(-) > > >=20 > > > diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c > > > index 3877b53e429f..a8dc9de2f7fb 100644 > > > --- a/fs/nfsd/nfs4callback.c > > > +++ b/fs/nfsd/nfs4callback.c > > > @@ -1036,8 +1036,7 @@ static void nfsd41_cb_inflight_begin(struct nfs= 4_client *clp) > > > static void nfsd41_cb_inflight_end(struct nfs4_client *clp) > > > { > > > =20 > > > - if (atomic_dec_and_test(&clp->cl_cb_inflight)) > > > - wake_up_var(&clp->cl_cb_inflight); > > > + atomic_dec_and_wake_up(&clp->cl_cb_inflight); > > > } > > > =20 > > > static void nfsd41_cb_inflight_wait_complete(struct nfs4_client *clp= ) > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > > index 741b9449f727..9fbf7c8f0a3e 100644 > > > --- a/fs/nfsd/nfs4state.c > > > +++ b/fs/nfsd/nfs4state.c > > > @@ -4739,7 +4739,7 @@ static void init_nfs4_replay(struct nfs4_replay= *rp) > > > rp->rp_status =3D nfserr_serverfault; > > > rp->rp_buflen =3D 0; > > > rp->rp_buf =3D rp->rp_ibuf; > > > - atomic_set(&rp->rp_locked, RP_UNLOCKED); > > > + rp->rp_locked =3D RP_UNLOCKED; > > > } > > > =20 > > > static int nfsd4_cstate_assign_replay(struct nfsd4_compound_state *c= state, > > > @@ -4747,9 +4747,9 @@ static int nfsd4_cstate_assign_replay(struct nf= sd4_compound_state *cstate, > > > { > > > if (!nfsd4_has_session(cstate)) { > > > wait_var_event(&so->so_replay.rp_locked, > > > - atomic_cmpxchg(&so->so_replay.rp_locked, > > > - RP_UNLOCKED, RP_LOCKED) !=3D RP_LOCKED); > > > - if (atomic_read(&so->so_replay.rp_locked) =3D=3D RP_UNHASHED) > > > + cmpxchg(&so->so_replay.rp_locked, > > > + RP_UNLOCKED, RP_LOCKED) !=3D RP_LOCKED); > >=20 > > nit: try_cmpxchg() generates more efficient assembly. Can we switch to > > that here too? >=20 > Does it? try_cmpxchg() makes loops smaller (as described in > atomic_t.txt). I think it wins when the "old" value has to be updated > each time around the loop. In this case the "old" value is always the > same. >=20 >=20 In most cases, it does, because we have to return "old" in the case of the traditional cmpxchg() operation. From atomic_t.txt: int atomic_cmpxchg(atomic_t *ptr, int old, int new) { (void)atomic_try_cmpxchg(ptr, &old, new); return old; } That said, in this case it my not be a win. You need something to return that value anyway, so it can properly act as a wait_var_event() condition. > >=20 > > > + if (so->so_replay.rp_locked =3D=3D RP_UNHASHED) > > > return -EAGAIN; > > > cstate->replay_owner =3D nfs4_get_stateowner(so); > > > } > > > @@ -4762,9 +4762,7 @@ void nfsd4_cstate_clear_replay(struct nfsd4_com= pound_state *cstate) > > > =20 > > > if (so !=3D NULL) { > > > cstate->replay_owner =3D NULL; > > > - atomic_set(&so->so_replay.rp_locked, RP_UNLOCKED); > > > - smp_mb__after_atomic(); > > > - wake_up_var(&so->so_replay.rp_locked); > > > + store_release_wake_up(&so->so_replay.rp_locked, RP_UNLOCKED); > > > nfs4_put_stateowner(so); > > > } > > > } > > > @@ -5069,9 +5067,7 @@ move_to_close_lru(struct nfs4_ol_stateid *s, st= ruct net *net) > > > * Some threads with a reference might be waiting for rp_locked, > > > * so tell them to stop waiting. > > > */ > > > - atomic_set(&oo->oo_owner.so_replay.rp_locked, RP_UNHASHED); > > > - smp_mb__after_atomic(); > > > - wake_up_var(&oo->oo_owner.so_replay.rp_locked); > > > + store_release_wake_up(&oo->oo_owner.so_replay.rp_locked, RP_UNHASHE= D); > > > wait_event(close_wq, refcount_read(&s->st_stid.sc_count) =3D=3D 2); > > > =20 > > > release_all_access(s); > > > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h > > > index e16bb3717fb9..ba30b2335b66 100644 > > > --- a/fs/nfsd/state.h > > > +++ b/fs/nfsd/state.h > > > @@ -505,7 +505,7 @@ struct nfs4_replay { > > > unsigned int rp_buflen; > > > char *rp_buf; > > > struct knfsd_fh rp_openfh; > > > - atomic_t rp_locked; > > > + int rp_locked; > > > char rp_ibuf[NFSD4_REPLAY_ISIZE]; > > > }; > > > =20 > >=20 > > Looks good otherwise. > >=20 > > Reviewed-by: Jeff Layton > >=20 >=20 --=20 Jeff Layton