Dan has reported two uses of uninitialized variables in __ris_msmon_read().
If an unknown monitor type is encountered then the local variable, now, is
used uninitialized. Fix this by returning early on error. If a non-mbwu
monitor is being read then the local variable, overflow, is not initialized
but still read. Initialize it to false as overflow is not relevant for csu
monitors.

Reported-by: kernel test robot <redacted>
Reported-by: Dan Carpenter <redacted>
Closes: https://lore.kernel.org/r/202512091519.RBwiJcSq-lkp@intel.com/ (local)
Closes: https://lore.kernel.org/r/202512100547.N7QPYgfb-lkp@intel.com/ (local)
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
 drivers/resctrl/mpam_devices.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 0b5b158e1aaf..b495d5291868 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c

@@ -1072,7 +1072,7 @@ static void __ris_msmon_read(void *arg)
 	u64 now;
 	bool nrdy = false;
 	bool config_mismatch;
-	bool overflow;
+	bool overflow = false;
 	struct mon_read *m = arg;
 	struct mon_cfg *ctx = m->ctx;
 	bool reset_on_next_read = false;

@@ -1176,10 +1176,11 @@ static void __ris_msmon_read(void *arg)
 	}
 	mpam_mon_sel_unlock(msc);
 
-	if (nrdy) {
+	if (nrdy)
 		m->err = -EBUSY;
+
+	if (m->err)
 		return;
-	}
 
 	*m->val += now;
 }

-- 
2.43.0