coresight: change coresight_device lock type to raw_spinlock_t

coresight_device->cscfg_csdev_lock can be held during __schedule()
by perf_event_task_sched_out()/in().

Since coresight->cscfg_csdev_lock type is spinlock_t and
perf_event_task_sched_out()/in() is called after acquiring rq_lock,
which is raw_spinlock_t (an unsleepable lock),
this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable.

To address this, change type of coresight_device->cscfg_csdev_lock
from spinlock_t to raw_spinlock_t.

Reviewed-by: James Clark <james.clark@linaro.org>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250306121110.1647948-2-yeoreum.yun@arm.com

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index 11138a9762b0150f674440f54bcaa438241d770b..a70c1454b4106c8847e85b8dae981608b762c030 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -89,9 +89,9 @@ static int cscfg_add_csdev_cfg(struct coresight_device *csdev,
        }
        /* if matched features, add config to device.*/
        if (config_csdev) {
-               spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
+               raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
                list_add(&config_csdev->node, &csdev->config_csdev_list);
-               spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+               raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
        }
 
        return 0;
@@ -194,9 +194,9 @@ static int cscfg_load_feat_csdev(struct coresight_device *csdev,
 
        /* add to internal csdev feature list & initialise using reset call */
        cscfg_reset_feat(feat_csdev);
-       spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        list_add(&feat_csdev->node, &csdev->feature_csdev_list);
-       spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
 
        return 0;
 }
@@ -765,7 +765,7 @@ static int cscfg_list_add_csdev(struct coresight_device *csdev,
 
        INIT_LIST_HEAD(&csdev->feature_csdev_list);
        INIT_LIST_HEAD(&csdev->config_csdev_list);
-       spin_lock_init(&csdev->cscfg_csdev_lock);
+       raw_spin_lock_init(&csdev->cscfg_csdev_lock);
 
        return 0;
 }
@@ -855,7 +855,7 @@ void cscfg_csdev_reset_feats(struct coresight_device *csdev)
        struct cscfg_feature_csdev *feat_csdev;
        unsigned long flags;
 
-       spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        if (list_empty(&csdev->feature_csdev_list))
                goto unlock_exit;
 
@@ -863,7 +863,7 @@ void cscfg_csdev_reset_feats(struct coresight_device *csdev)
                cscfg_reset_feat(feat_csdev);
 
 unlock_exit:
-       spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
 }
 EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);
 
@@ -1059,7 +1059,7 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
         * Look for matching configuration - set the active configuration
         * context if found.
         */
-       spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        list_for_each_entry(config_csdev_item, &csdev->config_csdev_list, node) {
                config_desc = config_csdev_item->config_desc;
                if ((atomic_read(&config_desc->active_cnt)) &&
@@ -1069,7 +1069,7 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
                        break;
                }
        }
-       spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
 
        /*
         * If found, attempt to enable
@@ -1090,12 +1090,12 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
                         *
                         * Set enabled if OK, err if not.
                         */
-                       spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
+                       raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
                        if (csdev->active_cscfg_ctxt)
                                config_csdev_active->enabled = true;
                        else
                                err = -EBUSY;
-                       spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+                       raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
                }
        }
        return err;
@@ -1124,7 +1124,7 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
         * If it was not enabled, we have no work to do, otherwise mark as disabled.
         * Clear the active config pointer.
         */
-       spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
        config_csdev = (struct cscfg_config_csdev *)csdev->active_cscfg_ctxt;
        if (config_csdev) {
                if (!config_csdev->enabled)
@@ -1133,7 +1133,7 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
                        config_csdev->enabled = false;
        }
        csdev->active_cscfg_ctxt = NULL;
-       spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
+       raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
 
        /* true if there was an enabled active config */
        if (config_csdev)

diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 89b781e70fe77247e09fb4f730b30f6c473f0276..4541bfc1cc6bb30c8f954c4ab1428459446400e2 100644 (file)
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -302,7 +302,7 @@ struct coresight_device {
        /* system configuration and feature lists */
        struct list_head feature_csdev_list;
        struct list_head config_csdev_list;
-       spinlock_t cscfg_csdev_lock;
+       raw_spinlock_t cscfg_csdev_lock;
        void *active_cscfg_ctxt;
 };