Messages in this thread | | | Date | Fri, 16 Apr 2021 19:50:02 +0800 | From | taozha@codeauro ... | Subject | Re: [PATCH] coresight: add support to enable more coresight paths |
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On 2021-04-15 17:49, Suzuki K Poulose wrote: > Hi > > On 15/04/2021 10:33, Tao Zhang wrote: >> Current coresight implementation only supports enabling source >> ETMs or STM. This patch adds support to enable more kinds of >> coresight source to sink paths. We build a path from source to >> sink when any source is enabled and store it in a list. When the >> source is disabled, we fetch the corresponding path from the list >> and decrement the refcount on each device in the path. The device >> is disabled if the refcount reaches zero. Don't store path to >> coresight data structure of source to avoid unnecessary change to >> ABI. >> Since some targets may have coresight sources other than STM and >> ETMs, we need to add this change to support these coresight >> devices. > > While I am not against the patch, I would like to see why this change > is > needed. Which compnents are we talking about , other than STM / ETM ? > Where is the "device" support code ? Without a legitimate user, we > cannot add this change in. > > Some other comments below. > We will upload coresight source device driver code in addition to STM/ETM in the future. This patch is only our first step. e.g, this patch can support to build a path from TPDM(a kind of coresight source device on Qualcomm target) to sink. At the same time, this patch also can support coresight source devices other than STM/ETM on the other targets. >> >> Signed-off-by: Satyajit Desai <sadesai@codeaurora.org> >> Signed-off-by: Rama Aparna Mallavarapu <aparnam@codeaurora.org> >> Signed-off-by: Mulu He <muluhe@codeaurora.org> >> Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org> >> Signed-off-by: Tao Zhang <taozha@codeaurora.org> >> --- >> drivers/hwtracing/coresight/coresight-core.c | 101 >> +++++++++++++++------------ >> 1 file changed, 56 insertions(+), 45 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-core.c >> b/drivers/hwtracing/coresight/coresight-core.c >> index 4ba801d..7dfadb6 100644 >> --- a/drivers/hwtracing/coresight/coresight-core.c >> +++ b/drivers/hwtracing/coresight/coresight-core.c >> @@ -35,18 +35,16 @@ struct coresight_node { >> }; >> /* >> - * When operating Coresight drivers from the sysFS interface, only a >> single >> - * path can exist from a tracer (associated to a CPU) to a sink. >> + * struct coresight_path - path from source to sink >> + * @path: Address of path list. >> + * @link: hook to the list. >> */ >> -static DEFINE_PER_CPU(struct list_head *, tracer_path); >> +struct coresight_path { >> + struct list_head *path; >> + struct list_head link; >> +}; >> -/* >> - * 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; >> +static LIST_HEAD(cs_active_paths); >> /* >> * When losing synchronisation a new barrier packet needs to be >> inserted at the >> @@ -326,7 +324,7 @@ static void coresight_disable_sink(struct >> coresight_device *csdev) >> if (ret) >> return; >> coresight_control_assoc_ectdev(csdev, false); >> - csdev->enable = false; >> + csdev->activated = false; >> } >> static int coresight_enable_link(struct coresight_device *csdev, >> @@ -562,6 +560,20 @@ int coresight_enable_path(struct list_head *path, >> u32 mode, void *sink_data) >> goto out; >> } >> +static struct coresight_device *coresight_get_source(struct >> list_head *path) >> +{ >> + struct coresight_device *csdev; >> + >> + if (!path) >> + return NULL; >> + >> + csdev = list_first_entry(path, struct coresight_node, link)->csdev; >> + if (csdev->type != CORESIGHT_DEV_TYPE_SOURCE) >> + return NULL; >> + >> + return csdev; >> +} >> + >> struct coresight_device *coresight_get_sink(struct list_head *path) >> { >> struct coresight_device *csdev; >> @@ -1047,9 +1059,23 @@ static int coresight_validate_source(struct >> coresight_device *csdev, >> return 0; >> } >> +static int coresight_store_path(struct list_head *path) >> +{ >> + struct coresight_path *node; >> + >> + node = kzalloc(sizeof(struct coresight_path), GFP_KERNEL); > > Have you run this with all the "DEBUG" whistles turned on ? This could > be problematic when called from a context where you are not allowed to > sleep. e.g, perf enable call back. > Only coresight_enable function will call coresight_store_path, and seems like coresight_enable function should be allowed to sleep since it is protected by Mutex. And I find in function coresight_build_path also will call kzalloc. Do you have any other concerns about calling kzalloc here? >> + if (!node) >> + return -ENOMEM; >> + >> + node->path = path; >> + list_add(&node->link, &cs_active_paths); >> + >> + return 0; >> +} >> + >> 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; >> @@ -1094,25 +1120,9 @@ 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; >> - } >> + ret = coresight_store_path(path); >> + if (ret) >> + goto err_source; >> out: >> mutex_unlock(&coresight_mutex); >> @@ -1129,8 +1139,11 @@ EXPORT_SYMBOL_GPL(coresight_enable); >> void coresight_disable(struct coresight_device *csdev) >> { >> - int cpu, ret; >> + int ret; >> struct list_head *path = NULL; >> + struct coresight_path *cspath = NULL; >> + struct coresight_path *cspath_next = NULL; >> + struct coresight_device *src_csdev = NULL; >> mutex_lock(&coresight_mutex); >> @@ -1141,20 +1154,18 @@ 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; > > --> Cut here <--- > >> + list_for_each_entry_safe(cspath, cspath_next, &cs_active_paths, >> link) { >> + src_csdev = coresight_get_source(cspath->path); >> + if (!src_csdev) >> + continue; >> + if (src_csdev == csdev) { >> + path = cspath->path; >> + list_del(&cspath->link); >> + kfree(cspath); >> + } >> } > > Why not add the above to > coresight_{retrieve/remove/}_active_path(csdev) ? > > > > Suzuki I didn't find coresight_{retrieve/remove/}_active_path(csdev) from coresight next branch. Can you help point out the exact function name that you think this part of code should be added to?
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