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Message-ID: <CAJ9a7VgA9YsEyQHMPVXG_8H-Kp_wpnd9ro1dGNV9CFzX+EqvWA@mail.gmail.com>
Date: Thu, 19 Dec 2024 12:23:37 +0000
From: Mike Leach <mike.leach@...aro.org>
To: Yeoreum Yun <yeoreum.yun@....com>
Cc: suzuki.poulose@....com, james.clark@...aro.org,
alexander.shishkin@...ux.intel.com, bigeasy@...utronix.de,
clrkwllms@...nel.org, rostedt@...dmis.org, coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-rt-devel@...ts.linux.dev
Subject: 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@....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@....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@...aro.org>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
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