This reverts commit 8fd52a21ab570e80f84f39e12affce42a5300e91.
Guenter Roeck linux@roeck-us.net writes:
I get the following build warning in v5.4.75.
drivers/hwtracing/coresight/coresight-etm-perf.c: In function 'etm_setup_aux': drivers/hwtracing/coresight/coresight-etm-perf.c:226:37: warning: passing argument 1 of 'coresight_get_enabled_sink' makes pointer from integer without a cast
Actually, the warning is fatal, since the call is sink = coresight_get_enabled_sink(true); However, the argument to coresight_get_enabled_sink() is now a pointer. The parameter change was introduced with commit 8fd52a21ab57 ("coresight: Make sysfs functional on topologies with per core sink").
In the upstream kernel, the call is removed with commit bb1860efc817 ("coresight: etm: perf: Sink selection using sysfs is deprecated"). That commit alone would, however, likely not solve the problem. It looks like at least two more commits would be needed.
716f5652a131 coresight: etm: perf: Fix warning caused by etm_setup_aux failure 8e264c52e1da coresight: core: Allow the coresight core driver to be built as a module 39a7661dcf65 coresight: Fix uninitialised pointer bug in etm_setup_aux()
Looking into the coresight code, I see several additional commits affecting the sysfs interface since v5.4. I have no idea what would actually be needed for stable code in v5.4.y, short of applying them all.
With all this in mind, I would suggest to revert commit 8fd52a21ab57 ("coresight: Make sysfs functional on topologies with per core sink") from v5.4.y, especially since it is not marked as bug fix or for stable.
Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hwtracing/coresight/coresight-priv.h | 3 +- drivers/hwtracing/coresight/coresight.c | 62 +++++++++++--------- 2 files changed, 36 insertions(+), 29 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index dfd24b85a5775..82e563cdc8794 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 90ecd04a2f20b..0bbce0d291582 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; - - /* - * Recursively explore each port found on this element. - */ - for (i = 0; i < csdev->pdata->nr_outport; i++) { - struct coresight_device *child_dev; + 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;
- 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; + + dev = bus_find_device(&coresight_bustype, NULL, &deactivate, + coresight_enabled_sink);
- return coresight_find_enabled_sink(source); + 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;