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From: Ben Horgan <ben.horgan@arm.com>
To: ben.horgan@arm.com
Cc: james.morse@arm.com, reinette.chatre@intel.com,
	fenghuay@nvidia.com, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, dave.martin@arm.com,
	andre.przywara@arm.com, Gavin Shan <gshan@redhat.com>
Subject: [PATCH v2 10/12] arm_mpam: Don't loop forever if there is the maximum possible amount of PARTIDs
Date: Thu, 17 Sep 2026 15:56:15 +0100	[thread overview]
Message-ID: <20260917145617.2202986-11-ben.horgan@arm.com> (raw)
In-Reply-To: <20260917145617.2202986-1-ben.horgan@arm.com>

On a theoretical platform with the maximum possible number of usable
PARTIDs, 0XFFFF, the loops iterating over PARTID in mpam_reset_ris() and
mpam_reprogram_ris() will never reach their termination condition leading
to a system hang when register the cpu hotplug handlers when MPAM is
enabling.

Fix these loops.

Fixes: f188a36ca241 ("arm_mpam: Reset MSC controls from cpuhp callbacks")
Fixes: 09b89d2a72f3 ("arm_mpam: Allow configuration to be applied and restored during cpu online")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Tested-by: Gavin Shan <gshan@redhat.com>
---
 drivers/resctrl/mpam_devices.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index cdc2d9d19e19..10fc5168699b 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -1754,7 +1754,7 @@ static int mpam_save_mbwu_state(void *arg)
  */
 static int mpam_reset_ris(void *arg)
 {
-	u16 partid, partid_max;
+	u16 partid_max;
 	struct mpam_config reset_cfg = {};
 	struct mpam_msc_ris *ris = arg;
 
@@ -1764,7 +1764,7 @@ static int mpam_reset_ris(void *arg)
 	spin_lock(&partid_max_lock);
 	partid_max = mpam_partid_max;
 	spin_unlock(&partid_max_lock);
-	for (partid = 0; partid <= partid_max; partid++)
+	for (u32 partid = 0; partid <= partid_max; partid++)
 		mpam_reprogram_ris_partid(ris, partid, &reset_cfg);
 
 	return 0;
@@ -1811,7 +1811,6 @@ static int __write_config(void *arg)
 
 static void mpam_reprogram_msc(struct mpam_msc *msc)
 {
-	u16 partid;
 	bool reset;
 	struct mpam_config *cfg;
 	struct mpam_msc_ris *ris;
@@ -1835,7 +1834,7 @@ static void mpam_reprogram_msc(struct mpam_msc *msc)
 		arg.comp = ris->vmsc->comp;
 		arg.ris = ris;
 		reset = true;
-		for (partid = 0; partid <= mpam_partid_max; partid++) {
+		for (u32 partid = 0; partid <= mpam_partid_max; partid++) {
 			cfg = &ris->vmsc->comp->cfg[partid];
 			if (!bitmap_empty(cfg->features, MPAM_FEATURE_LAST))
 				reset = false;
-- 
2.43.0



  parent reply	other threads:[~2026-09-17 14:57 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-17 14:56 [PATCH v2 00/12] arm_mpam: minor fixes at v7.2 Ben Horgan
2026-09-17 14:56 ` [PATCH v2 01/12] arm_mpam: Move MPAMF_ECR write helpers to allow reuse Ben Horgan
2026-09-22  5:41   ` Gavin Shan
2026-10-02 14:58   ` James Morse
2026-09-17 14:56 ` [PATCH v2 02/12] arm_mpam: Restore the error interrupt enable from mpam_cpu_online() Ben Horgan
2026-09-22  5:42   ` Gavin Shan
2026-10-02 15:00   ` James Morse
2026-09-17 14:56 ` [PATCH v2 03/12] arm_mpam: Set mpam_feat_msmon_mbwu_31counter when there are bandwidth counters Ben Horgan
2026-09-22  5:42   ` Gavin Shan
2026-10-02 15:01   ` James Morse
2026-09-17 14:56 ` [PATCH v2 04/12] arm_mpam: Add missing mon_sel locking in MBWU save and restore Ben Horgan
2026-10-02 15:01   ` James Morse
2026-10-02 15:28     ` Ben Horgan
2026-09-17 14:56 ` [PATCH v2 05/12] arm_mpam: Ensure MBWU counters are reset on restore Ben Horgan
2026-09-22  5:43   ` Gavin Shan
2026-10-02 15:13   ` James Morse
2026-10-02 15:24     ` Ben Horgan
2026-09-17 14:56 ` [PATCH v2 06/12] arm_mpam: Use __ris_msmon_read() for saving MBWU state Ben Horgan
2026-10-02 15:15   ` James Morse
2026-10-02 15:22     ` Ben Horgan
2026-10-02 16:21       ` James Morse
2026-09-17 14:56 ` [PATCH v2 07/12] arm_mpam: Initialize all of struct mon_read in mpam_restore_mbwu_state() Ben Horgan
2026-10-02 15:15   ` James Morse
2026-09-17 14:56 ` [PATCH v2 08/12] arm_mpam: resctrl: Correct check that existing class is L3 Ben Horgan
2026-09-22  5:43   ` Gavin Shan
2026-10-02 15:15   ` James Morse
2026-09-17 14:56 ` [PATCH v2 09/12] arm_mpam: resctrl: Make read_mon_cdp_safe() self consistent Ben Horgan
2026-09-22  5:44   ` Gavin Shan
2026-10-02 15:17   ` James Morse
2026-09-17 14:56 ` Ben Horgan [this message]
2026-09-22  5:44   ` [PATCH v2 10/12] arm_mpam: Don't loop forever if there is the maximum possible amount of PARTIDs Gavin Shan
2026-10-02 15:18   ` James Morse
2026-09-17 14:56 ` [PATCH v2 11/12] arm_mpam: Switch to kvzmalloc_objs() for allocation of component cfg Ben Horgan
2026-09-22  5:45   ` Gavin Shan
2026-10-02 15:18   ` James Morse
2026-09-17 14:56 ` [PATCH v2 12/12] arm_mpam: resctrl: Don't stop early when tearing down a class Ben Horgan
2026-09-22  5:45   ` Gavin Shan
2026-10-07 23:48 ` [PATCH v2 00/12] arm_mpam: minor fixes at v7.2 Shaopeng Tan (Fujitsu)

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