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[68.147.0.187]) by smtp.gmail.com with ESMTPSA id s28sm542173pfg.147.2021.12.14.10.30.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Dec 2021 10:30:13 -0800 (PST) Date: Tue, 14 Dec 2021 11:30:10 -0700 From: Mathieu Poirier To: Mao Jinlong Cc: Suzuki K Poulose , Alexander Shishkin , Mike Leach , Leo Yan , Greg Kroah-Hartman , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Tingwei Zhang , Yuanfang Zhang , Tao Zhang , Trilok Soni , linux-arm-msm@vger.kernel.org Subject: Re: [PATCH v2 1/9] Use IDR to maintain all the enabled sources' paths. Message-ID: <20211214183010.GA1549991@p14s> References: <20211209141543.21314-1-quic_jinlmao@quicinc.com> <20211209141543.21314-2-quic_jinlmao@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211209141543.21314-2-quic_jinlmao@quicinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mao, On Thu, Dec 09, 2021 at 10:15:35PM +0800, Mao Jinlong wrote: > Use hash length of the source's device name to map to the pointer > of the enabled path. Using IDR will be more efficient than using > the list. And there could be other sources except STM and CPU etms > in the new HWs. It is better to maintain all the paths together. > > Signed-off-by: Mao Jinlong > --- > drivers/hwtracing/coresight/coresight-core.c | 76 +++++++------------- > 1 file changed, 26 insertions(+), 50 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c > index 8a18c71df37a..cc6b6cabf85f 100644 > --- a/drivers/hwtracing/coresight/coresight-core.c > +++ b/drivers/hwtracing/coresight/coresight-core.c > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -26,6 +27,12 @@ > static DEFINE_MUTEX(coresight_mutex); > static DEFINE_PER_CPU(struct coresight_device *, csdev_sink); > > +/* > + * Use IDR to map the hash length of the source's device name > + * to the pointer of path for the source > + */ > +static DEFINE_IDR(path_idr); > + > /** > * struct coresight_node - elements of a path, from source to sink > * @csdev: Address of an element. > @@ -36,20 +43,6 @@ struct coresight_node { > struct list_head link; > }; > > -/* > - * When operating Coresight drivers from the sysFS interface, only a single > - * path can exist from a tracer (associated to a CPU) to a sink. > - */ > -static DEFINE_PER_CPU(struct list_head *, tracer_path); > - > -/* > - * As of this writing only a single STM can be found in CS topologies. Since > - * there is no way to know if we'll ever see more and what kind of > - * configuration they will enact, for the time being only define a single path > - * for STM. > - */ > -static struct list_head *stm_path; > - > /* > * When losing synchronisation a new barrier packet needs to be inserted at the > * beginning of the data collected in a buffer. That way the decoder knows that > @@ -1088,10 +1081,11 @@ static int coresight_validate_source(struct coresight_device *csdev, > > int coresight_enable(struct coresight_device *csdev) > { > - int cpu, ret = 0; > + int ret = 0; > struct coresight_device *sink; > struct list_head *path; > enum coresight_dev_subtype_source subtype; > + u32 hash; > > subtype = csdev->subtype.source_subtype; > > @@ -1133,26 +1127,14 @@ int coresight_enable(struct coresight_device *csdev) > if (ret) > goto err_source; > > - switch (subtype) { > - case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC: > - /* > - * When working from sysFS it is important to keep track > - * of the paths that were created so that they can be > - * undone in 'coresight_disable()'. Since there can only > - * be a single session per tracer (when working from sysFS) > - * a per-cpu variable will do just fine. > - */ > - cpu = source_ops(csdev)->cpu_id(csdev); > - per_cpu(tracer_path, cpu) = path; > - break; > - case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE: > - stm_path = path; > - break; > - default: > - /* We can't be here */ > - break; > - } > - > + /* > + * Use the hash length of source's device name as ID > + * and map the ID to the pointer of the path. > + */ > + hash = hashlen_hash(hashlen_string(NULL, dev_name(&csdev->dev))); > + ret = idr_alloc_u32(&path_idr, path, &hash, hash, GFP_KERNEL); > + if (ret) > + goto err_source; > out: > mutex_unlock(&coresight_mutex); > return ret; > @@ -1168,8 +1150,9 @@ EXPORT_SYMBOL_GPL(coresight_enable); > > void coresight_disable(struct coresight_device *csdev) > { > - int cpu, ret; > + int ret; > struct list_head *path = NULL; > + u32 hash; > > mutex_lock(&coresight_mutex); > > @@ -1180,21 +1163,13 @@ void coresight_disable(struct coresight_device *csdev) > if (!csdev->enable || !coresight_disable_source(csdev)) > goto out; > > - switch (csdev->subtype.source_subtype) { > - case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC: > - cpu = source_ops(csdev)->cpu_id(csdev); > - path = per_cpu(tracer_path, cpu); > - per_cpu(tracer_path, cpu) = NULL; > - break; > - case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE: > - path = stm_path; > - stm_path = NULL; > - break; > - default: > - /* We can't be here */ > - break; > - } > + hash = hashlen_hash(hashlen_string(NULL, dev_name(&csdev->dev))); > + /* Find the path by the hash length. */ > + path = idr_find(&path_idr, hash); > + if (path == NULL) > + return; Please add a dev_err() here as this should really not be happening. > > + idr_remove(&path_idr, hash); > coresight_disable_path(path); > coresight_release_path(path); > > @@ -1779,6 +1754,7 @@ static int __init coresight_init(void) > > static void __exit coresight_exit(void) > { > + idr_destroy(&path_idr); As far as I can tell this isn't needed. > cscfg_exit(); > etm_perf_exit(); > bus_unregister(&coresight_bustype); > -- > 2.17.1 >