linux-kernel - [PATCH v2 01/45] arm_mpam: Stop using uninitialized variables in __ris_msmon

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Message-ID: <20251219181147.3404071-2-ben.horgan@arm.com>
Date: Fri, 19 Dec 2025 18:11:03 +0000
From: Ben Horgan <ben.horgan@....com>
To: ben.horgan@....com
Cc: amitsinght@...vell.com,
	baisheng.gao@...soc.com,
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	kvmarm@...ts.linux.dev,
	kernel test robot <lkp@...el.com>,
	Dan Carpenter <dan.carpenter@...aro.org>
Subject: [PATCH v2 01/45] arm_mpam: Stop using uninitialized variables in __ris_msmon_read()

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 <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/r/202512091519.RBwiJcSq-lkp@intel.com/
Closes: https://lore.kernel.org/r/202512100547.N7QPYgfb-lkp@intel.com/
Signed-off-by: Ben Horgan <ben.horgan@....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