This is a note to let you know that I've just added the patch titled
perf/arm-cmn: Fix PMU instance naming
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-arm-cmn-fix-pmu-instance-naming.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 89b556dd59fe17a9839f92e8936fa59d89bcb584
Author: Robin Murphy <robin.murphy@xxxxxxx>
Date: Thu Jan 28 13:12:43 2021 +0000
perf/arm-cmn: Fix PMU instance naming
[ Upstream commit 79d7c3dca99fa96033695ddf5d495b775a3a137b ]
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: 0ba64770a2f2 ("perf: Add Arm CMN-600 PMU driver")
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Link: https://lore.kernel.org/r/649a2281233f193d59240b13ed91b57337c77b32.1611839564.git.robin.murphy@xxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/Documentation/admin-guide/perf/arm-cmn.rst b/Documentation/admin-guide/perf/arm-cmn.rst
index 0e48093460140..796e25b7027b2 100644
--- a/Documentation/admin-guide/perf/arm-cmn.rst
+++ b/Documentation/admin-guide/perf/arm-cmn.rst
@@ -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}.
diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index a76ff594f3ca4..f3071b5ddaaef 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -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)
