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

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

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 yeoreum.yun@arm.com

.../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}

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