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

In coresight-etb10 drivers, etb_drvdata->spinlock can be held during __schedule() by perf_event_task_sched_out()/in().

Since etb_drvdata->spinlock 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 etb_drvdata->spinlock in coresight-etb10 drivers, which can be called by perf_event_task_sched_out()/in(), from spinlock_t to raw_spinlock_t.

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

drivers/hwtracing/coresight/coresight-etb10.c | 26 +++++++++---------- 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c index aea9ac9c4bd0..7948597d483d 100644 --- a/drivers/hwtracing/coresight/coresight-etb10.c +++ b/drivers/hwtracing/coresight/coresight-etb10.c @@ -84,7 +84,7 @@ struct etb_drvdata { struct clk *atclk; struct coresight_device *csdev; struct miscdevice miscdev;

•   spinlock_t              spinlock;
  

•   raw_spinlock_t          spinlock;
    local_t                 reading;
    pid_t                   pid;
    u8                      *buf;
  

@@ -145,7 +145,7 @@ static int etb_enable_sysfs(struct coresight_device *csdev) unsigned long flags; struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

•   spin_lock_irqsave(&drvdata->spinlock, flags);
  

•   raw_spin_lock_irqsave(&drvdata->spinlock, flags);
  
    /* Don't messup with perf sessions. */
    if (coresight_get_mode(csdev) == CS_MODE_PERF) {
  

@@ -163,7 +163,7 @@ static int etb_enable_sysfs(struct coresight_device *csdev)

    csdev->refcnt++;

out:

•   spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•   raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
    return ret;
  

}

@@ -176,7 +176,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data) struct perf_output_handle *handle = data; struct cs_buffers *buf = etm_perf_sink_config(handle);

•   spin_lock_irqsave(&drvdata->spinlock, flags);
  

•   raw_spin_lock_irqsave(&drvdata->spinlock, flags);
  
    /* No need to continue if the component is already in used by sysFS. */
    if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
  

@@ -219,7 +219,7 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data) }

out:

•   spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•   raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
    return ret;
  

}

@@ -352,11 +352,11 @@ static int etb_disable(struct coresight_device *csdev) struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); unsigned long flags;

•   spin_lock_irqsave(&drvdata->spinlock, flags);
  

•   raw_spin_lock_irqsave(&drvdata->spinlock, flags);
  
    csdev->refcnt--;
    if (csdev->refcnt) {
  

•           spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•           raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
            return -EBUSY;
    }
  
  

@@ -366,7 +366,7 @@ static int etb_disable(struct coresight_device *csdev) /* Dissociate from monitored process. */ drvdata->pid = -1; coresight_set_mode(csdev, CS_MODE_DISABLED);

•   spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•   raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
  
    dev_dbg(&csdev->dev, "ETB disabled\n");
    return 0;
  

@@ -443,7 +443,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,

    capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS;

•   spin_lock_irqsave(&drvdata->spinlock, flags);
  

•   raw_spin_lock_irqsave(&drvdata->spinlock, flags);
  
    /* Don't do anything if another tracer is using this sink */
    if (csdev->refcnt != 1)
  

@@ -566,7 +566,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev, __etb_enable_hw(drvdata); CS_LOCK(drvdata->base); out:

•   spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•   raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
  
    return to_read;
  

} @@ -587,13 +587,13 @@ static void etb_dump(struct etb_drvdata *drvdata) { unsigned long flags;

•   spin_lock_irqsave(&drvdata->spinlock, flags);
  

•   raw_spin_lock_irqsave(&drvdata->spinlock, flags);
    if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
            __etb_disable_hw(drvdata);
            etb_dump_hw(drvdata);
            __etb_enable_hw(drvdata);
    }
  

•   spin_unlock_irqrestore(&drvdata->spinlock, flags);
  

•   raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
  
    dev_dbg(&drvdata->csdev->dev, "ETB dumped\n");
  

} @@ -746,7 +746,7 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id) drvdata->base = base; desc.access = CSDEV_ACCESS_IOMEM(base);

•   spin_lock_init(&drvdata->spinlock);
  

•   raw_spin_lock_init(&drvdata->spinlock);
  
    drvdata->buffer_depth = etb_get_buffer_depth(drvdata);
  
  

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

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

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