From mboxrd@z Thu Jan 1 00:00:00 1970 From: Madalin-cristian Bucur Subject: RE: [PATCH net-next] net: dpaa: remove init which already done in per-cpu allocation Date: Mon, 30 Oct 2017 07:17:04 +0000 Message-ID: References: <1509241724-16997-1-git-send-email-cugyly@163.com> <2673700892724b47842afbf3ab36c541@nokia-sbell.com> <87a1676ac7b74da3aa744c3f3cc6f0bf@nokia-sbell.com> <3c448bbf3ebb4de0843b78af23435ba0@nokia-sbell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Cc: "David S . Miller" To: Madalin-cristian Bucur , "Yuan, Linyu (NSB - CN/Shanghai)" , yuan linyu , "netdev@vger.kernel.org" , "gregkh@linuxfoundation.org" , "edumazet@google.com" Return-path: Received: from mail-eopbgr10075.outbound.protection.outlook.com ([40.107.1.75]:45328 "EHLO EUR02-HE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751167AbdJ3HRH (ORCPT ); Mon, 30 Oct 2017 03:17:07 -0400 In-Reply-To: Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: > +Eric >=20 > > -----Original Message----- > > From: Yuan, Linyu (NSB - CN/Shanghai) [mailto:linyu.yuan@nokia- > sbell.com] > > > > I just saw below accepted commit, it said "per cpu allocations are > already > > zeroed, no need to clear them again." > > > > > https://emea01.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2Fgit.= ker > nel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fdavem%2Fnet- > next.git%2Fcommit%2F%3Fid%3Dbfd8e5a407133e58a92a38ccf3d0ba6db81f22d8&data= =3D > 02%7C01%7Cmadalin.bucur%40nxp.com%7C4116c18371684740c41a08d51f65c6e9%7C68= 6 > ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C636449444348895856&sdata=3DPBvP4J= 0ch > 8o%2Bvif3C8D77dVxGW4vjUlCYwJzJcIzhFk%3D&reserved=3D0 > > > > I will not touch memory sub-system, so I will not change this function > > description. > > >=20 > Your particular change removes redundancy, it's fine. Having the memset > documented > somewhere would prevent similar redundancy from being added in the future= . >=20 > > > -----Original Message----- > > > From: Madalin-cristian Bucur [mailto:madalin.bucur@nxp.com] > > > Sent: Monday, October 30, 2017 1:56 PM > > > To: Yuan, Linyu (NSB - CN/Shanghai); yuan linyu; > netdev@vger.kernel.org; > > > gregkh@linuxfoundation.org > > > Cc: David S . Miller > > > Subject: RE: [PATCH net-next] net: dpaa: remove init which already > done > > in > > > per-cpu allocation > > > > > > Also here: > > > > > > > > > > https://emea01.safelinks.protection.outlook.com/?url=3Dhttp%3A%2F%2Felixi= r.f > ree- > electrons.com%2Flinux%2Flatest%2Fsource%2Fmm%2Fpercpu.c%23L717&data=3D02%= 7C0 > 1%7Cmadalin.bucur%40nxp.com%7C4116c18371684740c41a08d51f65c6e9%7C686ea1d3= b > c2b4c6fa92cd99c5c301635%7C0%7C0%7C636449444348895856&sdata=3DG9AEcoAPE7yW= H%2 > FHi56DP3zns8LaIixJ4xkuQCTJDI5E%3D&reserved=3D0 > > > > > > Should the fact that the memory is zeroed be included in the function > > > description? > > > > > > /** > > > * pcpu_alloc - the percpu allocator > > > * @size: size of area to allocate in bytes > > > * @align: alignment of area (max PAGE_SIZE) > > > * @reserved: allocate from the reserved chunk if available > > > * @gfp: allocation flags > > > * > > > * Allocate percpu area of @size bytes aligned at @align. If @gfp > > doesn't > > > * contain %GFP_KERNEL, the allocation is atomic. > > > * > > > * RETURNS: > > > * Percpu pointer to the allocated area on success, NULL on failure. > > > */ > > > > > > Now it seems to be an implementation detail rather than a guarantee. > > > > > > Looking at Documentation/driver-model/devres.txt, the memset is not > > > mentioned there either. > > > > > > > -----Original Message----- > > > > From: Yuan, Linyu (NSB - CN/Shanghai) [mailto:linyu.yuan@nokia- > > sbell.com] > > > > Sent: Monday, October 30, 2017 7:21 AM > > > > To: Madalin-cristian Bucur ; yuan linyu > > > > ; netdev@vger.kernel.org > > > > Cc: David S . Miller > > > > Subject: RE: [PATCH net-next] net: dpaa: remove init which already > > > > done in per-cpu allocation > > > > > > > > > https://emea01.safelinks.protection.outlook.com/?url=3Dhttp%3A%2F%2Felixi= r.f > ree- > electrons.com%2Flinux%2Flatest%2Fsource%2Fmm%2Fpercpu.c%23L1018&data=3D02= %7C > 01%7Cmadalin.bucur%40nxp.com%7C4116c18371684740c41a08d51f65c6e9%7C686ea1d= 3 > bc2b4c6fa92cd99c5c301635%7C0%7C0%7C636449444348895856&sdata=3D%2FOCOMao4j= Jti > ptOqUUXBbZMt5TNRXdFfyrqa1zIekAI%3D&reserved=3D0 > > > > > > > > > -----Original Message----- > > > > > From: Madalin-cristian Bucur [mailto:madalin.bucur@nxp.com] > > > > > Sent: Monday, October 30, 2017 1:15 PM > > > > > To: Yuan, Linyu (NSB - CN/Shanghai); yuan linyu; > > netdev@vger.kernel.org > > > > > Cc: David S . Miller > > > > > Subject: RE: [PATCH net-next] net: dpaa: remove init which alread= y > > > > > done in per-cpu allocation > > > > > > > > > > Is the memset part documented? > > > > > Can you point to the specific comment & code that does it? > > > > > > > > > > Thanks > > > > > > > > > > > -----Original Message----- > > > > > > From: Yuan, Linyu (NSB - CN/Shanghai) [mailto:linyu.yuan@nokia- > > > > sbell.com] > > > > > > Sent: Monday, October 30, 2017 7:12 AM > > > > > > To: Madalin-cristian Bucur ; yuan linyu > > > > > > ; netdev@vger.kernel.org > > > > > > Cc: David S . Miller > > > > > > Subject: RE: [PATCH net-next] net: dpaa: remove init which > already > > > > done in > > > > > > per-cpu allocation > > > > > > > > > > > > Hi, > > > > > > > > > > > > devm_alloc_percpu() will allocate per-cpu memory and memset > > allocated > > > > > > block content to 0. > > > > > > > > > > > > > -----Original Message----- > > > > > > > From: Madalin-cristian Bucur [mailto:madalin.bucur@nxp.com] > > > > > > > Sent: Monday, October 30, 2017 1:08 PM > > > > > > > To: yuan linyu; netdev@vger.kernel.org > > > > > > > Cc: David S . Miller; Yuan, Linyu (NSB - CN/Shanghai) > > > > > > > Subject: RE: [PATCH net-next] net: dpaa: remove init which > > > > > > > already done in per-cpu allocation > > > > > > > > > > > > > > Hi Yuan, > > > > > > > > > > > > > > Can you please give more details about this change you are > > > > proposing? > > > > > > > > > > > > > > Regards, > > > > > > > Madalin > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > > From: netdev-owner@vger.kernel.org > > > > > > > [mailto:netdev-owner@vger.kernel.org] > > > > > > > > On Behalf Of yuan linyu > > > > > > > > Sent: Sunday, October 29, 2017 3:49 AM > > > > > > > > To: netdev@vger.kernel.org > > > > > > > > Cc: David S . Miller ; yuan linyu > > > > > > > > > > > > > > > > Subject: [PATCH net-next] net: dpaa: remove init which > already > > > > done in > > > > > > > > per-cpu allocation > > > > > > > > > > > > > > > > From: yuan linyu > > > > > > > > > > > > > > > > Signed-off-by: yuan linyu > > > > > > > > --- > > > > > > > > drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 4 ---- > > > > > > > > 1 file changed, 4 deletions(-) > > > > > > > > > > > > > > > > diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c > > > > > > > > b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c > > > > > > > > index a8d0be8..1ccc316 100644 > > > > > > > > --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c > > > > > > > > +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c > > > > > > > > @@ -2814,10 +2814,6 @@ static int dpaa_eth_probe(struct > > > > > > > platform_device > > > > > > > > *pdev) > > > > > > > > err =3D -ENOMEM; > > > > > > > > goto free_dpaa_fqs; > > > > > > > > } > > > > > > > > - for_each_possible_cpu(i) { > > > > > > > > - percpu_priv =3D per_cpu_ptr(priv->percpu_priv, i); > > > > > > > > - memset(percpu_priv, 0, sizeof(*percpu_priv)); > > > > > > > > - } > > > > > > > > > > > > > > > > priv->num_tc =3D 1; > > > > > > > > netif_set_real_num_tx_queues(net_dev, priv->num_tc * > > > > > > > > DPAA_TC_TXQ_NUM); > > > > > > > > -- > > > > > > > > 2.7.4 > > > > > > > >