coresight-etb10: change etb_drvdata spinlock's type to raw_spinlock_t

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.

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/20250306121110.1647948-6-yeoreum.yun@arm.com

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index aea9ac9c4bd0699768235b367d738f0f89af27f2..7948597d483d2bb6b3bd4e644de78133206df2c3 100644 (file)
--- 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);