[PATCH v2 10/12] arm_mpam: Don't loop forever if there is the maximum possible amount of PARTIDs
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WARM1d
REVIEWED: 1 (0M)
From: Ben Horgan <ben.horgan@arm.com>
Date: 2026-09-17 14:57:03
Also in:
lkml
Subsystem:
mpam driver, the rest · Maintainers:
James Morse, Ben Horgan, Linus Torvalds
Revision v2 of 2 in this series; 1 review trailer.
Revisions (2)
- v1 [diff vs current]
- v2 current
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 <redacted>
---
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