[PATCH v2] arm_mpam: Only schedule mpam_enable work after first successful MSC probe

[ping.li]

From: Ping Li <leeonion.muyu@xxxxxxxxx>

mpam_discovery_cpu_online() sets new_device_probed unconditionally after
processing each reachable MSC. Once an MSC has already been probed
(msc->probed is true), later CPUs sharing it skip
mpam_msc_hw_probe() but still leave err at its default value of 0.
As a result, new_device_probed is still set to true, causing
mpam_enable_work to be scheduled again even though no new hardware was
probed.

Set new_device_probed only when mpam_msc_hw_probe() is called and
succeeds.

Signed-off-by: Ping Li <leeonion.muyu@xxxxxxxxx>
---
Changes in v2:
- Drop the Fixes: tag, as the extra mpam_enable() calls cause no real
  harm: schedule_work() merges the duplicate work, and mpam_enable()
  is a no-op until all MSCs have been probed. This is a cleanup, not a
  bug fix.

 drivers/resctrl/mpam_devices.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 2f09f4b78bd3..fefdcf588932 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -1866,13 +1866,15 @@ static int mpam_discovery_cpu_online(unsigned int cpu)
 			continue;
 
 		mutex_lock(&msc->probe_lock);
-		if (!msc->probed)
+		if (!msc->probed) {
 			err = mpam_msc_hw_probe(msc);
+			if (!err)
+				new_device_probed = true;
+		}
 		mutex_unlock(&msc->probe_lock);
 
 		if (err)
 			break;
-		new_device_probed = true;
 	}
 
 	if (new_device_probed && !err)
-- 
2.34.1