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Revert "coresight: Make sysfs functional on topologies with per core sink"

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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>
This commit is contained in:
Sasha Levin 2020-11-08 08:28:09 -05:00 committed by Greg Kroah-Hartman
parent 8ee6a0f254
commit cfd9d71377
2 changed files with 36 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/hwtracing/coresight/coresight-priv.h
View File

@ -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);

62
drivers/hwtracing/coresight/coresight.c
View File

@ -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;