From: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Date: Mon, 26 Jan 2026 17:42:42 +0000 (-0800)
Subject: drm/xe/multi_queue: Protect priority against concurrent access
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=e694179a2c02700087185bc300ba81dd17b7ad40;p=thirdparty%2Flinux.git

drm/xe/multi_queue: Protect priority against concurrent access

Use a spinlock to protect multi-queue priority being concurrently
updated by multiple set_priority ioctls and to protect against
concurrent read and write to this field.

v2: Update documentation, remove WRITE/READ_LOCK() (Thomas)
    Use scoped_guard, reduced lock scope (Matt Brost)
v3: Fix author (checkpatch)

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20260126174241.3470390-2-niranjana.vishwanathapura@intel.com
---

diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
index 7e7e663189e4a..66d0e10ee2c4a 100644
--- a/drivers/gpu/drm/xe/xe_exec_queue.c
+++ b/drivers/gpu/drm/xe/xe_exec_queue.c
@@ -230,6 +230,7 @@ static struct xe_exec_queue *__xe_exec_queue_alloc(struct xe_device *xe,
 	INIT_LIST_HEAD(&q->multi_gt_link);
 	INIT_LIST_HEAD(&q->hw_engine_group_link);
 	INIT_LIST_HEAD(&q->pxp.link);
+	spin_lock_init(&q->multi_queue.lock);
 	q->multi_queue.priority = XE_MULTI_QUEUE_PRIORITY_NORMAL;
 
 	q->sched_props.timeslice_us = hwe->eclass->sched_props.timeslice_us;
diff --git a/drivers/gpu/drm/xe/xe_exec_queue_types.h b/drivers/gpu/drm/xe/xe_exec_queue_types.h
index e987d431ce27f..3791fed34ffa5 100644
--- a/drivers/gpu/drm/xe/xe_exec_queue_types.h
+++ b/drivers/gpu/drm/xe/xe_exec_queue_types.h
@@ -161,8 +161,13 @@ struct xe_exec_queue {
 		struct xe_exec_queue_group *group;
 		/** @multi_queue.link: Link into group's secondary queues list */
 		struct list_head link;
-		/** @multi_queue.priority: Queue priority within the multi-queue group */
+		/**
+		 * @multi_queue.priority: Queue priority within the multi-queue group.
+		 * It is protected by @multi_queue.lock.
+		 */
 		enum xe_multi_queue_priority priority;
+		/** @multi_queue.lock: Lock for protecting certain members */
+		spinlock_t lock;
 		/** @multi_queue.pos: Position of queue within the multi-queue group */
 		u8 pos;
 		/** @multi_queue.valid: Queue belongs to a multi queue group */
diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 456f549c16f6f..1f4625ddae0ea 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -804,6 +804,7 @@ static void xe_guc_exec_queue_group_cgp_sync(struct xe_guc *guc,
 {
 	struct xe_exec_queue_group *group = q->multi_queue.group;
 	struct xe_device *xe = guc_to_xe(guc);
+	enum xe_multi_queue_priority priority;
 	long ret;
 
 	/*
@@ -827,7 +828,10 @@ static void xe_guc_exec_queue_group_cgp_sync(struct xe_guc *guc,
 		return;
 	}
 
-	xe_lrc_set_multi_queue_priority(q->lrc[0], q->multi_queue.priority);
+	scoped_guard(spinlock, &q->multi_queue.lock)
+		priority = q->multi_queue.priority;
+
+	xe_lrc_set_multi_queue_priority(q->lrc[0], priority);
 	xe_guc_exec_queue_group_cgp_update(xe, q);
 
 	WRITE_ONCE(group->sync_pending, true);
@@ -2181,15 +2185,22 @@ static int guc_exec_queue_set_multi_queue_priority(struct xe_exec_queue *q,
 
 	xe_gt_assert(guc_to_gt(exec_queue_to_guc(q)), xe_exec_queue_is_multi_queue(q));
 
-	if (q->multi_queue.priority == priority ||
-	    exec_queue_killed_or_banned_or_wedged(q))
+	if (exec_queue_killed_or_banned_or_wedged(q))
 		return 0;
 
 	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
 	if (!msg)
 		return -ENOMEM;
 
-	q->multi_queue.priority = priority;
+	scoped_guard(spinlock, &q->multi_queue.lock) {
+		if (q->multi_queue.priority == priority) {
+			kfree(msg);
+			return 0;
+		}
+
+		q->multi_queue.priority = priority;
+	}
+
 	guc_exec_queue_add_msg(q, msg, SET_MULTI_QUEUE_PRIORITY);
 
 	return 0;