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coresight: Move reference counting inside sink drivers

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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: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Robert Walker <robert.walker@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mathieu Poirier 2019-04-25 13:52:56 -06:00 committed by Greg Kroah-Hartman
parent 6c817a95d8
commit f973d88b75
5 changed files with 66 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/hwtracing/coresight/coresight-etb10.c
View File

@ -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)
goto out;
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);

21
drivers/hwtracing/coresight/coresight-tmc-etf.c
View File

@ -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);

19
drivers/hwtracing/coresight/coresight-tmc-etr.c
View File

@ -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);

6
drivers/hwtracing/coresight/coresight-tpiu.c
View File

@ -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");

28
drivers/hwtracing/coresight/coresight.c
View File

@ -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) {
ret = sink_ops(csdev)->enable(csdev, mode, data);
if (ret)
return ret;
csdev->enable = true;
}
if (!sink_ops(csdev)->enable)
return -EINVAL;
atomic_inc(csdev->refcnt);
ret = sink_ops(csdev)->enable(csdev, mode, data);
if (ret)
return ret;
csdev->enable = true;
return 0;
}
@ -241,14 +240,13 @@ static void coresight_disable_sink(struct coresight_device *csdev)
{
int ret;
if (atomic_dec_return(csdev->refcnt) == 0) {
if (sink_ops(csdev)->disable) {
ret = sink_ops(csdev)->disable(csdev);
if (ret)
return;
csdev->enable = false;
}
}
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,