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Tue, 26 Mar 2024 09:25:44 -0700 (PDT) Received: from debian ([2601:641:300:14de:69a2:b1ff:1efd:f4a9]) by smtp.gmail.com with ESMTPSA id d2-20020a170903230200b001e0d70680acsm2649542plh.268.2024.03.26.09.25.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Mar 2024 09:25:44 -0700 (PDT) From: fan X-Google-Original-From: fan Date: Tue, 26 Mar 2024 09:25:40 -0700 To: Ira Weiny Cc: Dave Jiang , Fan Ni , Jonathan Cameron , Navneet Singh , Dan Williams , Davidlohr Bueso , Alison Schofield , Vishal Verma , linux-btrfs@vger.kernel.org, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 05/26] cxl/core: Simplify cxl_dpa_set_mode() Message-ID: References: <20240324-dcd-type2-upstream-v1-0-b7b00d623625@intel.com> <20240324-dcd-type2-upstream-v1-5-b7b00d623625@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240324-dcd-type2-upstream-v1-5-b7b00d623625@intel.com> On Sun, Mar 24, 2024 at 04:18:08PM -0700, Ira Weiny wrote: > cxl_dpa_set_mode() checks the mode for validity two times, once outside > of the DPA RW semaphore and again within. The function is not in a > critical path. Prior to Dynamic Capacity the extra check was not much > of an issue. The addition of DC modes increases the complexity of > the check. > > Simplify the mode check before adding the more complex DC modes. > > Signed-off-by: Ira Weiny > Reviewed-by: Fan Ni > --- > Changes for v1: > [iweiny: new patch] > [Jonathan: based on getting rid of the loop in cxl_dpa_set_mode] > [Jonathan: standardize on resource_size() == 0] > --- > drivers/cxl/core/hdm.c | 45 ++++++++++++++++++--------------------------- > 1 file changed, 18 insertions(+), 27 deletions(-) > > diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c > index 7d97790b893d..66b8419fd0c3 100644 > --- a/drivers/cxl/core/hdm.c > +++ b/drivers/cxl/core/hdm.c > @@ -411,44 +411,35 @@ int cxl_dpa_set_mode(struct cxl_endpoint_decoder *cxled, > struct cxl_memdev *cxlmd = cxled_to_memdev(cxled); > struct cxl_dev_state *cxlds = cxlmd->cxlds; > struct device *dev = &cxled->cxld.dev; > - int rc; > > + guard(rwsem_write)(&cxl_dpa_rwsem); > + if (cxled->cxld.flags & CXL_DECODER_F_ENABLE) > + return -EBUSY; > + > + /* > + * Check that the mode is supported by the current partition > + * configuration > + */ > switch (mode) { > case CXL_DECODER_RAM: > + if (!resource_size(&cxlds->ram_res)) { > + dev_dbg(dev, "no available ram capacity\n"); > + return -ENXIO; > + } > + break; > case CXL_DECODER_PMEM: > + if (!resource_size(&cxlds->pmem_res)) { > + dev_dbg(dev, "no available pmem capacity\n"); > + return -ENXIO; > + } > break; > default: > dev_dbg(dev, "unsupported mode: %d\n", mode); > return -EINVAL; > } > > - down_write(&cxl_dpa_rwsem); > - if (cxled->cxld.flags & CXL_DECODER_F_ENABLE) { > - rc = -EBUSY; > - goto out; > - } > - > - /* > - * Only allow modes that are supported by the current partition > - * configuration > - */ > - if (mode == CXL_DECODER_PMEM && !resource_size(&cxlds->pmem_res)) { > - dev_dbg(dev, "no available pmem capacity\n"); > - rc = -ENXIO; > - goto out; > - } > - if (mode == CXL_DECODER_RAM && !resource_size(&cxlds->ram_res)) { > - dev_dbg(dev, "no available ram capacity\n"); > - rc = -ENXIO; > - goto out; > - } > - > cxled->mode = mode; > - rc = 0; > -out: > - up_write(&cxl_dpa_rwsem); > - > - return rc; > + return 0; > } > > int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size) > > -- > 2.44.0 >