Re: [PATCH v3 1/9] coresight: change coresight_device lock type to raw_spinlock_t

On Mon, 16 Dec 2024 at 11:50, Yeoreum Yun yeoreum.yun@arm.com wrote:

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.

Signed-off-by: Yeoreum Yun yeoreum.yun@arm.com

.../hwtracing/coresight/coresight-syscfg.c | 26 +++++++++---------- include/linux/coresight.h | 2 +- 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c index 11138a9762b0..a70c1454b410 100644 --- 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 c13342594278..924b58c343b3 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -296,7 +296,7 @@ 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;
  

};

-- LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}

Reviewed-by: Mike Leach mike.leach@linaro.org

-- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK