Commit f973d88b authored by Mathieu Poirier's avatar Mathieu Poirier Committed by Greg Kroah-Hartman
Browse files

coresight: Move reference counting inside sink drivers 



When operating in CPU-wide mode with an N:1 source/sink HW topology,
multiple CPUs can access a sink concurrently.  As such reference counting
needs to happen when the device's spinlock is held to avoid racing with
other operations (start(), update(), stop()), such as:

session A				Session B
-----					-------

enable_sink
atomic_inc(refcount)  = 1

...

atomic_dec(refcount) = 0		enable_sink
if (refcount == 0) disable_sink
					atomic_inc()

Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: default avatarLeo Yan <leo.yan@linaro.org>
Tested-by: default avatarRobert Walker <robert.walker@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6c817a95

drivers/hwtracing/coresight/coresight-etb10.c

+15 −6
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
 * Description: CoreSight Embedded Trace Buffer driver

 */



#include <linux/atomic.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/types.h>
@@ -151,14 +152,15 @@ static int etb_enable_sysfs(struct coresight_device *csdev) 
		goto out;

	}



	/* Nothing to do, the tracer is already enabled. */

	if (drvdata->mode == CS_MODE_SYSFS)

	if (drvdata->mode == CS_MODE_DISABLED) {

		ret = etb_enable_hw(drvdata);

		if (ret)

			goto out;



	ret = etb_enable_hw(drvdata);

	if (!ret)

		drvdata->mode = CS_MODE_SYSFS;

	}



	atomic_inc(csdev->refcnt);

out:

	spin_unlock_irqrestore(&drvdata->spinlock, flags);

	return ret;
@@ -188,8 +190,10 @@ static int etb_enable_perf(struct coresight_device *csdev, void *data) 
		goto out;



	ret = etb_enable_hw(drvdata);

	if (!ret)

	if (!ret) {

		drvdata->mode = CS_MODE_PERF;

		atomic_inc(csdev->refcnt);

	}



out:

	spin_unlock_irqrestore(&drvdata->spinlock, flags);
@@ -324,6 +328,11 @@ static int etb_disable(struct coresight_device *csdev) 


	spin_lock_irqsave(&drvdata->spinlock, flags);



	if (atomic_dec_return(csdev->refcnt)) {

		spin_unlock_irqrestore(&drvdata->spinlock, flags);

		return -EBUSY;

	}



	/* Disable the ETB only if it needs to */

	if (drvdata->mode != CS_MODE_DISABLED) {

		etb_disable_hw(drvdata);

drivers/hwtracing/coresight/coresight-tmc-etf.c

+17 −4
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
 * Author: Mathieu Poirier <mathieu.poirier@linaro.org>

 */



#include <linux/atomic.h>

#include <linux/circ_buf.h>

#include <linux/coresight.h>

#include <linux/perf_event.h>
@@ -180,8 +181,10 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev) 
	 * sink is already enabled no memory is needed and the HW need not be

	 * touched.

	 */

	if (drvdata->mode == CS_MODE_SYSFS)

	if (drvdata->mode == CS_MODE_SYSFS) {

		atomic_inc(csdev->refcnt);

		goto out;

	}



	/*

	 * If drvdata::buf isn't NULL, memory was allocated for a previous
@@ -200,11 +203,13 @@ static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev) 
	}



	ret = tmc_etb_enable_hw(drvdata);

	if (!ret)

	if (!ret) {

		drvdata->mode = CS_MODE_SYSFS;

	else

		atomic_inc(csdev->refcnt);

	} else {

		/* Free up the buffer if we failed to enable */

		used = false;

	}

out:

	spin_unlock_irqrestore(&drvdata->spinlock, flags);
@@ -239,8 +244,10 @@ static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, void *data) 
		if (ret)

			break;

		ret  = tmc_etb_enable_hw(drvdata);

		if (!ret)

		if (!ret) {

			drvdata->mode = CS_MODE_PERF;

			atomic_inc(csdev->refcnt);

		}

	} while (0);

	spin_unlock_irqrestore(&drvdata->spinlock, flags);
@@ -279,11 +286,17 @@ static int tmc_disable_etf_sink(struct coresight_device *csdev) 
	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);



	spin_lock_irqsave(&drvdata->spinlock, flags);



	if (drvdata->reading) {

		spin_unlock_irqrestore(&drvdata->spinlock, flags);

		return -EBUSY;

	}



	if (atomic_dec_return(csdev->refcnt)) {

		spin_unlock_irqrestore(&drvdata->spinlock, flags);

		return -EBUSY;

	}



	/* Disable the TMC only if it needs to */

	if (drvdata->mode != CS_MODE_DISABLED) {

		tmc_etb_disable_hw(drvdata);

drivers/hwtracing/coresight/coresight-tmc-etr.c

+16 −3
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
 * Author: Mathieu Poirier <mathieu.poirier@linaro.org>

 */



#include <linux/atomic.h>

#include <linux/coresight.h>

#include <linux/dma-mapping.h>

#include <linux/iommu.h>
@@ -1125,8 +1126,10 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev) 
	 * sink is already enabled no memory is needed and the HW need not be

	 * touched, even if the buffer size has changed.

	 */

	if (drvdata->mode == CS_MODE_SYSFS)

	if (drvdata->mode == CS_MODE_SYSFS) {

		atomic_inc(csdev->refcnt);

		goto out;

	}



	/*

	 * If we don't have a buffer or it doesn't match the requested size,
@@ -1139,8 +1142,10 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev) 
	}



	ret = tmc_etr_enable_hw(drvdata, drvdata->sysfs_buf);

	if (!ret)

	if (!ret) {

		drvdata->mode = CS_MODE_SYSFS;

		atomic_inc(csdev->refcnt);

	}

out:

	spin_unlock_irqrestore(&drvdata->spinlock, flags);
@@ -1371,8 +1376,10 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data) 
	etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf);

	drvdata->perf_data = etr_perf;

	rc = tmc_etr_enable_hw(drvdata, etr_perf->etr_buf);

	if (!rc)

	if (!rc) {

		drvdata->mode = CS_MODE_PERF;

		atomic_inc(csdev->refcnt);

	}



unlock_out:

	spin_unlock_irqrestore(&drvdata->spinlock, flags);
@@ -1399,11 +1406,17 @@ static int tmc_disable_etr_sink(struct coresight_device *csdev) 
	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);



	spin_lock_irqsave(&drvdata->spinlock, flags);



	if (drvdata->reading) {

		spin_unlock_irqrestore(&drvdata->spinlock, flags);

		return -EBUSY;

	}



	if (atomic_dec_return(csdev->refcnt)) {

		spin_unlock_irqrestore(&drvdata->spinlock, flags);

		return -EBUSY;

	}



	/* Disable the TMC only if it needs to */

	if (drvdata->mode != CS_MODE_DISABLED) {

		tmc_etr_disable_hw(drvdata);

drivers/hwtracing/coresight/coresight-tpiu.c

+5 −1
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
 * Description: CoreSight Trace Port Interface Unit driver

 */



#include <linux/atomic.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/device.h>
@@ -73,7 +74,7 @@ static int tpiu_enable(struct coresight_device *csdev, u32 mode, void *__unused) 
	struct tpiu_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);



	tpiu_enable_hw(drvdata);



	atomic_inc(csdev->refcnt);

	dev_dbg(drvdata->dev, "TPIU enabled\n");

	return 0;

}
@@ -98,6 +99,9 @@ static int tpiu_disable(struct coresight_device *csdev) 
{

	struct tpiu_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);



	if (atomic_dec_return(csdev->refcnt))

		return -EBUSY;



	tpiu_disable_hw(drvdata);



	dev_dbg(drvdata->dev, "TPIU disabled\n");

drivers/hwtracing/coresight/coresight.c

+13 −15
Original line number Diff line number Diff line
@@ -225,14 +225,13 @@ static int coresight_enable_sink(struct coresight_device *csdev, 
	 * We need to make sure the "new" session is compatible with the

	 * existing "mode" of operation.

	 */

	if (sink_ops(csdev)->enable) {

	if (!sink_ops(csdev)->enable)

		return -EINVAL;



	ret = sink_ops(csdev)->enable(csdev, mode, data);

	if (ret)

		return ret;

	csdev->enable = true;

	}



	atomic_inc(csdev->refcnt);



	return 0;

}
@@ -241,15 +240,14 @@ static void coresight_disable_sink(struct coresight_device *csdev) 
{

	int ret;



	if (atomic_dec_return(csdev->refcnt) == 0) {

		if (sink_ops(csdev)->disable) {

	if (!sink_ops(csdev)->disable)

		return;



	ret = sink_ops(csdev)->disable(csdev);

	if (ret)

		return;

	csdev->enable = false;

}

	}

}



static int coresight_enable_link(struct coresight_device *csdev,

				 struct coresight_device *parent,

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