coresight/ultrasoc: change smb_drv_data spinlock's type to raw_spinlock_t

In ultrasoc-smb drivers, smb_drv_data->spinlock can be held
during __schedule() by perf_event_task_sched_out()/in().

Since smb__drv_data->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 smb_drv_data->spinlock in ultrasoc-smb 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>
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/20250306121110.1647948-10-yeoreum.yun@arm.com

diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c
index dc3c9504dd7cd2429ddd22f9fe830d3426e919d3..26cfc939e5bd810295a336f392ac282ccf316f9f 100644 (file)
--- a/drivers/hwtracing/coresight/ultrasoc-smb.c
+++ b/drivers/hwtracing/coresight/ultrasoc-smb.c
@@ -98,7 +98,7 @@ static int smb_open(struct inode *inode, struct file *file)
        struct smb_drv_data *drvdata = container_of(file->private_data,
                                        struct smb_drv_data, miscdev);
 
-       guard(spinlock)(&drvdata->spinlock);
+       guard(raw_spinlock)(&drvdata->spinlock);
 
        if (drvdata->reading)
                return -EBUSY;
@@ -152,7 +152,7 @@ static int smb_release(struct inode *inode, struct file *file)
        struct smb_drv_data *drvdata = container_of(file->private_data,
                                        struct smb_drv_data, miscdev);
 
-       guard(spinlock)(&drvdata->spinlock);
+       guard(raw_spinlock)(&drvdata->spinlock);
        drvdata->reading = false;
 
        return 0;
@@ -245,7 +245,7 @@ static int smb_enable(struct coresight_device *csdev, enum cs_mode mode,
        struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
        int ret = 0;
 
-       guard(spinlock)(&drvdata->spinlock);
+       guard(raw_spinlock)(&drvdata->spinlock);
 
        /* Do nothing, the trace data is reading by other interface now */
        if (drvdata->reading)
@@ -280,7 +280,7 @@ static int smb_disable(struct coresight_device *csdev)
 {
        struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
 
-       guard(spinlock)(&drvdata->spinlock);
+       guard(raw_spinlock)(&drvdata->spinlock);
 
        if (drvdata->reading)
                return -EBUSY;
@@ -378,7 +378,7 @@ static unsigned long smb_update_buffer(struct coresight_device *csdev,
        if (!buf)
                return 0;
 
-       guard(spinlock)(&drvdata->spinlock);
+       guard(raw_spinlock)(&drvdata->spinlock);
 
        /* Don't do anything if another tracer is using this sink. */
        if (csdev->refcnt != 1)
@@ -563,7 +563,7 @@ static int smb_probe(struct platform_device *pdev)
 
        smb_reset_buffer(drvdata);
        platform_set_drvdata(pdev, drvdata);
-       spin_lock_init(&drvdata->spinlock);
+       raw_spin_lock_init(&drvdata->spinlock);
        drvdata->pid = -1;
 
        ret = smb_register_sink(pdev, drvdata);

diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.h b/drivers/hwtracing/coresight/ultrasoc-smb.h
index a91d39cfccb8fcedabcd96c61fecaf9c193672ea..c4c111275627b1d662a9adc82058008e73527a28 100644 (file)
--- a/drivers/hwtracing/coresight/ultrasoc-smb.h
+++ b/drivers/hwtracing/coresight/ultrasoc-smb.h
@@ -115,7 +115,7 @@ struct smb_drv_data {
        struct coresight_device *csdev;
        struct smb_data_buffer sdb;
        struct miscdevice miscdev;
-       spinlock_t spinlock;
+       raw_spinlock_t spinlock;
        bool reading;
        pid_t pid;
 };