Re: [PATCH v3 8/9] coresight-tmc: change tmc_drvdata spinlock's type to raw_spinlock_t

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

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

Signed-off-by: Yeoreum Yun <redacted>
---
 .../hwtracing/coresight/coresight-tmc-core.c  |  6 +--
 .../hwtracing/coresight/coresight-tmc-etf.c   | 48 +++++++++----------
 .../hwtracing/coresight/coresight-tmc-etr.c   | 40 ++++++++--------
 drivers/hwtracing/coresight/coresight-tmc.h   |  2 +-
 4 files changed, 48 insertions(+), 48 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index e9876252a789..4e9925300931 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c

@@ -492,7 +492,7 @@ static int __tmc_probe(struct device *dev, struct resource *res)
        drvdata->base = base;
        desc.access = CSDEV_ACCESS_IOMEM(base);

-       spin_lock_init(&drvdata->spinlock);
+       raw_spin_lock_init(&drvdata->spinlock);

        devid = readl_relaxed(drvdata->base + CORESIGHT_DEVID);
        drvdata->config_type = BMVAL(devid, 6, 7);

@@ -596,7 +596,7 @@ static void tmc_shutdown(struct amba_device *adev)
        unsigned long flags;
        struct tmc_drvdata *drvdata = amba_get_drvdata(adev);

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);

        if (coresight_get_mode(drvdata->csdev) == CS_MODE_DISABLED)
                goto out;

@@ -610,7 +610,7 @@ static void tmc_shutdown(struct amba_device *adev)
         * the system is going down after this.
         */
 out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 }

 static void __tmc_remove(struct device *dev)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index d4f641cd9de6..fca8e9ffb3cf 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c

@@ -182,9 +182,9 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
         * If we don't have a buffer release the lock and allocate memory.
         * Otherwise keep the lock and move along.
         */
-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);
        if (!drvdata->buf) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

                /* Allocating the memory here while outside of the spinlock */
                buf = kzalloc(drvdata->size, GFP_KERNEL);

@@ -192,7 +192,7 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
                        return -ENOMEM;

                /* Let's try again */
-               spin_lock_irqsave(&drvdata->spinlock, flags);
+               raw_spin_lock_irqsave(&drvdata->spinlock, flags);
        }

        if (drvdata->reading) {

@@ -235,7 +235,7 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev)
                used = false;
        }
 out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        /* Free memory outside the spinlock if need be */
        if (!used)

@@ -253,7 +253,7 @@ static int tmc_enable_etf_sink_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);
        do {
                ret = -EINVAL;
                if (drvdata->reading)

@@ -296,7 +296,7 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data)
                        csdev->refcnt++;
                }
        } while (0);
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        return ret;
 }

@@ -331,16 +331,16 @@ static int tmc_disable_etf_sink(struct coresight_device *csdev)
        unsigned long flags;
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);

        if (drvdata->reading) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

        csdev->refcnt--;
        if (csdev->refcnt) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

@@ -351,7 +351,7 @@ static int tmc_disable_etf_sink(struct coresight_device *csdev)
        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, "TMC-ETB/ETF disabled\n");
        return 0;

@@ -366,9 +366,9 @@ static int tmc_enable_etf_link(struct coresight_device *csdev,
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        bool first_enable = false;

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);
        if (drvdata->reading) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

@@ -381,7 +381,7 @@ static int tmc_enable_etf_link(struct coresight_device *csdev,
        }
        if (!ret)
                csdev->refcnt++;
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        if (first_enable)
                dev_dbg(&csdev->dev, "TMC-ETF enabled\n");

@@ -396,9 +396,9 @@ static void tmc_disable_etf_link(struct coresight_device *csdev,
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        bool last_disable = false;

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);
        if (drvdata->reading) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return;
        }

@@ -408,7 +408,7 @@ static void tmc_disable_etf_link(struct coresight_device *csdev,
                coresight_set_mode(csdev, CS_MODE_DISABLED);
                last_disable = true;
        }
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        if (last_disable)
                dev_dbg(&csdev->dev, "TMC-ETF disabled\n");

@@ -488,7 +488,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
        if (WARN_ON_ONCE(coresight_get_mode(csdev) != CS_MODE_PERF))
                return 0;

-       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)

@@ -585,7 +585,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
         */
        CS_LOCK(drvdata->base);
 out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        return to_read;
 }

@@ -623,7 +623,7 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
                         drvdata->config_type != TMC_CONFIG_TYPE_ETF))
                return -EINVAL;

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);

        if (drvdata->reading) {
                ret = -EBUSY;

@@ -655,7 +655,7 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)

        drvdata->reading = true;
 out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        return ret;
 }

@@ -672,14 +672,14 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
                         drvdata->config_type != TMC_CONFIG_TYPE_ETF))
                return -EINVAL;

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);

        /* Re-enable the TMC if need be */
        if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
                /* There is no point in reading a TMC in HW FIFO mode */
                mode = readl_relaxed(drvdata->base + TMC_MODE);
                if (mode != TMC_MODE_CIRCULAR_BUFFER) {
-                       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+                       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                        return -EINVAL;
                }
                /*

@@ -693,7 +693,7 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
                memset(drvdata->buf, 0, drvdata->size);
                rc = __tmc_etb_enable_hw(drvdata);
                if (rc) {
-                       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+                       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                        return rc;
                }
        } else {

@@ -706,7 +706,7 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
        }

        drvdata->reading = false;
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        /*
         * Free allocated memory outside of the spinlock.  There is no need

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index a48bb85d0e7f..a0a90ce7333e 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c

@@ -1176,10 +1176,10 @@ static struct etr_buf *tmc_etr_get_sysfs_buffer(struct coresight_device *csdev)
         * buffer, provided the size matches. Any allocation has to be done
         * with the lock released.
         */
-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);
        sysfs_buf = READ_ONCE(drvdata->sysfs_buf);
        if (!sysfs_buf || (sysfs_buf->size != drvdata->size)) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

                /* Allocate memory with the locks released */
                free_buf = new_buf = tmc_etr_setup_sysfs_buf(drvdata);

@@ -1187,7 +1187,7 @@ static struct etr_buf *tmc_etr_get_sysfs_buffer(struct coresight_device *csdev)
                        return new_buf;

                /* Let's try again */
-               spin_lock_irqsave(&drvdata->spinlock, flags);
+               raw_spin_lock_irqsave(&drvdata->spinlock, flags);
        }

        if (drvdata->reading || coresight_get_mode(csdev) == CS_MODE_PERF) {

@@ -1206,7 +1206,7 @@ static struct etr_buf *tmc_etr_get_sysfs_buffer(struct coresight_device *csdev)
        }

 out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        /* Free memory outside the spinlock if need be */
        if (free_buf)

@@ -1224,7 +1224,7 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
        if (IS_ERR(sysfs_buf))
                return PTR_ERR(sysfs_buf);

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);

        /*
         * In sysFS mode we can have multiple writers per sink.  Since this

@@ -1243,7 +1243,7 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
        }

 out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        if (!ret)
                dev_dbg(&csdev->dev, "TMC-ETR enabled\n");

@@ -1562,17 +1562,17 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
        struct etr_perf_buffer *etr_perf = config;
        struct etr_buf *etr_buf = etr_perf->etr_buf;

-       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) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                goto out;
        }

        if (WARN_ON(drvdata->perf_buf != etr_buf)) {
                lost = true;
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                goto out;
        }

@@ -1582,7 +1582,7 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
        tmc_sync_etr_buf(drvdata);

        CS_LOCK(drvdata->base);
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        lost = etr_buf->full;
        offset = etr_buf->offset;

@@ -1651,7 +1651,7 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
        struct perf_output_handle *handle = data;
        struct etr_perf_buffer *etr_perf = etm_perf_sink_config(handle);

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);
         /* Don't use this sink if it is already claimed by sysFS */
        if (coresight_get_mode(csdev) == CS_MODE_SYSFS) {
                rc = -EBUSY;

@@ -1691,7 +1691,7 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
        }

 unlock_out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
        return rc;
 }

@@ -1713,16 +1713,16 @@ static int tmc_disable_etr_sink(struct coresight_device *csdev)
        unsigned long flags;
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);

        if (drvdata->reading) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

        csdev->refcnt--;
        if (csdev->refcnt) {
-               spin_unlock_irqrestore(&drvdata->spinlock, flags);
+               raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

@@ -1735,7 +1735,7 @@ static int tmc_disable_etr_sink(struct coresight_device *csdev)
        /* Reset perf specific data */
        drvdata->perf_buf = NULL;

-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        dev_dbg(&csdev->dev, "TMC-ETR disabled\n");
        return 0;

@@ -1762,7 +1762,7 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
        if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETR))
                return -EINVAL;

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);
        if (drvdata->reading) {
                ret = -EBUSY;
                goto out;

@@ -1784,7 +1784,7 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)

        drvdata->reading = true;
 out:
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        return ret;
 }

@@ -1798,7 +1798,7 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
        if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETR))
                return -EINVAL;

-       spin_lock_irqsave(&drvdata->spinlock, flags);
+       raw_spin_lock_irqsave(&drvdata->spinlock, flags);

        /* RE-enable the TMC if need be */
        if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {

@@ -1818,7 +1818,7 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
        }

        drvdata->reading = false;
-       spin_unlock_irqrestore(&drvdata->spinlock, flags);
+       raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);

        /* Free allocated memory out side of the spinlock */
        if (sysfs_buf)

diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index 2671926be62a..60b395025bc4 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h

@@ -195,7 +195,7 @@ struct tmc_drvdata {
        void __iomem            *base;
        struct coresight_device *csdev;
        struct miscdevice       miscdev;
-       spinlock_t              spinlock;
+       raw_spinlock_t          spinlock;
        pid_t                   pid;
        bool                    reading;
        union {
--

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