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perf/arm-cmn: Fix PMU instance naming

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Although it's neat to avoid the suffix for the typical case of a
single PMU, it means systems with multiple CMN instances end up with
inconsistent naming. I think it also breaks perf tool's "uncore alias"
logic if the common instance prefix is also the full name of one.

Avoid any surprises by not trying to be clever and simply numbering
every instance, even when it might technically prove redundant.

Fixes: 0ba64770a2 ("perf: Add Arm CMN-600 PMU driver")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/649a2281233f193d59240b13ed91b57337c77b32.1611839564.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Robin Murphy 2021-01-28 13:12:43 +00:00 committed by Will Deacon
parent f0c140481d
commit 79d7c3dca9
2 changed files with 5 additions and 10 deletions
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2
Documentation/admin-guide/perf/arm-cmn.rst
View File

@ -17,7 +17,7 @@ PMU events
----------
The PMU driver registers a single PMU device for the whole interconnect,
see /sys/bus/event_source/devices/arm_cmn. Multi-chip systems may link
see /sys/bus/event_source/devices/arm_cmn_0. Multi-chip systems may link
more than one CMN together via external CCIX links - in this situation,
each mesh counts its own events entirely independently, and additional
PMU devices will be named arm_cmn_{1..n}.

13
drivers/perf/arm-cmn.c
View File

@ -1502,7 +1502,7 @@ static int arm_cmn_probe(struct platform_device *pdev)
struct arm_cmn *cmn;
const char *name;
static atomic_t id;
int err, rootnode, this_id;
int err, rootnode;
cmn = devm_kzalloc(&pdev->dev, sizeof(*cmn), GFP_KERNEL);
if (!cmn)
@ -1549,14 +1549,9 @@ static int arm_cmn_probe(struct platform_device *pdev)
.cancel_txn = arm_cmn_end_txn,
};
this_id = atomic_fetch_inc(&id);
if (this_id == 0) {
name = "arm_cmn";
} else {
name = devm_kasprintf(cmn->dev, GFP_KERNEL, "arm_cmn_%d", this_id);
if (!name)
return -ENOMEM;
}
name = devm_kasprintf(cmn->dev, GFP_KERNEL, "arm_cmn_%d", atomic_fetch_inc(&id));
if (!name)
return -ENOMEM;
err = cpuhp_state_add_instance(arm_cmn_hp_state, &cmn->cpuhp_node);
if (err)