diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index dfd24b85a577..82e563cdc879 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -147,8 +147,7 @@ static inline void coresight_write_reg_pair(void __iomem *addr, u64 val, void coresight_disable_path(struct list_head *path); int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data); struct coresight_device *coresight_get_sink(struct list_head *path); -struct coresight_device * -coresight_get_enabled_sink(struct coresight_device *source); +struct coresight_device *coresight_get_enabled_sink(bool reset); struct coresight_device *coresight_get_sink_by_id(u32 id); struct list_head *coresight_build_path(struct coresight_device *csdev, struct coresight_device *sink); diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index 90ecd04a2f20..0bbce0d29158 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -481,46 +481,50 @@ struct coresight_device *coresight_get_sink(struct list_head *path) return csdev; } -static struct coresight_device * -coresight_find_enabled_sink(struct coresight_device *csdev) +static int coresight_enabled_sink(struct device *dev, const void *data) { - int i; - struct coresight_device *sink; + const bool *reset = data; + struct coresight_device *csdev = to_coresight_device(dev); if ((csdev->type == CORESIGHT_DEV_TYPE_SINK || csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) && - csdev->activated) - return csdev; + csdev->activated) { + /* + * Now that we have a handle on the sink for this session, + * disable the sysFS "enable_sink" flag so that possible + * concurrent perf session that wish to use another sink don't + * trip on it. Doing so has no ramification for the current + * session. + */ + if (*reset) + csdev->activated = false; - /* - * Recursively explore each port found on this element. - */ - for (i = 0; i < csdev->pdata->nr_outport; i++) { - struct coresight_device *child_dev; - - child_dev = csdev->pdata->conns[i].child_dev; - if (child_dev) - sink = coresight_find_enabled_sink(child_dev); - if (sink) - return sink; + return 1; } - return NULL; + return 0; } /** - * coresight_get_enabled_sink - returns the first enabled sink using - * connection based search starting from the source reference + * coresight_get_enabled_sink - returns the first enabled sink found on the bus + * @deactivate: Whether the 'enable_sink' flag should be reset * - * @source: Coresight source device reference + * When operated from perf the deactivate parameter should be set to 'true'. + * That way the "enabled_sink" flag of the sink that was selected can be reset, + * allowing for other concurrent perf sessions to choose a different sink. + * + * When operated from sysFS users have full control and as such the deactivate + * parameter should be set to 'false', hence mandating users to explicitly + * clear the flag. */ -struct coresight_device * -coresight_get_enabled_sink(struct coresight_device *source) +struct coresight_device *coresight_get_enabled_sink(bool deactivate) { - if (!source) - return NULL; + struct device *dev = NULL; - return coresight_find_enabled_sink(source); + dev = bus_find_device(&coresight_bustype, NULL, &deactivate, + coresight_enabled_sink); + + return dev ? to_coresight_device(dev) : NULL; } static int coresight_sink_by_id(struct device *dev, const void *data) @@ -760,7 +764,11 @@ int coresight_enable(struct coresight_device *csdev) goto out; } - sink = coresight_get_enabled_sink(csdev); + /* + * Search for a valid sink for this session but don't reset the + * "enable_sink" flag in sysFS. Users get to do that explicitly. + */ + sink = coresight_get_enabled_sink(false); if (!sink) { ret = -EINVAL; goto out;