diff mbox series

[v2,04/16] coresight: Adding return code to sink::disable() operation

Message ID 20190325215632.17013-5-mathieu.poirier@linaro.org (mailing list archive)
State New, archived
Headers show
Series coresight: Add support for CPU-wide trace scenarios | expand

Commit Message

Mathieu Poirier March 25, 2019, 9:56 p.m. UTC 
In preparation to handle device reference counting inside of the sink
drivers, add a return code to the sink::disable() operation so that
proper action can be taken if a sink has not been disabled.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-etb10.c   | 3 ++-
 drivers/hwtracing/coresight/coresight-tmc-etf.c | 5 +++--
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++--
 drivers/hwtracing/coresight/coresight-tpiu.c    | 3 ++-
 drivers/hwtracing/coresight/coresight.c         | 6 +++++-
 include/linux/coresight.h                       | 2 +-
 6 files changed, 16 insertions(+), 8 deletions(-)

Comments

Suzuki K Poulose March 26, 2019, 2:55 p.m. UTC | #1 
On 03/25/2019 09:56 PM, Mathieu Poirier wrote:
> In preparation to handle device reference counting inside of the sink
> drivers, add a return code to the sink::disable() operation so that
> proper action can be taken if a sink has not been disabled.
> 
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

This one and the next patch in the series, together fixes an issue
where we could leave the a sink still enabled, but with refcounts
dropped. (i.e, if we collide with someone reading the sink, while
trying to disable).

As such the issue has been lying around since the beginning, we don't
have to bother about fixing the issue in one single patch.

Thus,

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
diff mbox series

Patch

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 105782ea64c7..71c2a3cdb866 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -325,7 +325,7 @@  static void etb_disable_hw(struct etb_drvdata *drvdata)
 	coresight_disclaim_device(drvdata->base);
 }
 
-static void etb_disable(struct coresight_device *csdev)
+static int etb_disable(struct coresight_device *csdev)
 {
 	struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 	unsigned long flags;
@@ -340,6 +340,7 @@  static void etb_disable(struct coresight_device *csdev)
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	dev_dbg(drvdata->dev, "ETB disabled\n");
+	return 0;
 }
 
 static void *etb_alloc_buffer(struct coresight_device *csdev, int cpu,
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index a5f053f2db2c..d4213e7c2c45 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -273,7 +273,7 @@  static int tmc_enable_etf_sink(struct coresight_device *csdev,
 	return 0;
 }
 
-static void tmc_disable_etf_sink(struct coresight_device *csdev)
+static int tmc_disable_etf_sink(struct coresight_device *csdev)
 {
 	unsigned long flags;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
@@ -281,7 +281,7 @@  static void tmc_disable_etf_sink(struct coresight_device *csdev)
 	spin_lock_irqsave(&drvdata->spinlock, flags);
 	if (drvdata->reading) {
 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
-		return;
+		return -EBUSY;
 	}
 
 	/* Disable the TMC only if it needs to */
@@ -293,6 +293,7 @@  static void tmc_disable_etf_sink(struct coresight_device *csdev)
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	dev_dbg(drvdata->dev, "TMC-ETB/ETF disabled\n");
+	return 0;
 }
 
 static int tmc_enable_etf_link(struct coresight_device *csdev,
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index f684283890d3..33501777038a 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1392,7 +1392,7 @@  static int tmc_enable_etr_sink(struct coresight_device *csdev,
 	return -EINVAL;
 }
 
-static void tmc_disable_etr_sink(struct coresight_device *csdev)
+static int tmc_disable_etr_sink(struct coresight_device *csdev)
 {
 	unsigned long flags;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
@@ -1400,7 +1400,7 @@  static void tmc_disable_etr_sink(struct coresight_device *csdev)
 	spin_lock_irqsave(&drvdata->spinlock, flags);
 	if (drvdata->reading) {
 		spin_unlock_irqrestore(&drvdata->spinlock, flags);
-		return;
+		return -EBUSY;
 	}
 
 	/* Disable the TMC only if it needs to */
@@ -1412,6 +1412,7 @@  static void tmc_disable_etr_sink(struct coresight_device *csdev)
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	dev_dbg(drvdata->dev, "TMC-ETR disabled\n");
+	return 0;
 }
 
 static const struct coresight_ops_sink tmc_etr_sink_ops = {
diff --git a/drivers/hwtracing/coresight/coresight-tpiu.c b/drivers/hwtracing/coresight/coresight-tpiu.c
index b2f72a1fa402..0d13da1b9df1 100644
--- a/drivers/hwtracing/coresight/coresight-tpiu.c
+++ b/drivers/hwtracing/coresight/coresight-tpiu.c
@@ -94,13 +94,14 @@  static void tpiu_disable_hw(struct tpiu_drvdata *drvdata)
 	CS_LOCK(drvdata->base);
 }
 
-static void tpiu_disable(struct coresight_device *csdev)
+static int tpiu_disable(struct coresight_device *csdev)
 {
 	struct tpiu_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
 	tpiu_disable_hw(drvdata);
 
 	dev_dbg(drvdata->dev, "TPIU disabled\n");
+	return 0;
 }
 
 static const struct coresight_ops_sink tpiu_sink_ops = {
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 29cef898afba..13eda4693f81 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -239,9 +239,13 @@  static int coresight_enable_sink(struct coresight_device *csdev,
 
 static void coresight_disable_sink(struct coresight_device *csdev)
 {
+	int ret;
+
 	if (atomic_dec_return(csdev->refcnt) == 0) {
 		if (sink_ops(csdev)->disable) {
-			sink_ops(csdev)->disable(csdev);
+			ret = sink_ops(csdev)->disable(csdev);
+			if (ret)
+				return;
 			csdev->enable = false;
 		}
 	}
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 7b87965f7a65..189cc6ddc92b 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -192,7 +192,7 @@  struct coresight_device {
  */
 struct coresight_ops_sink {
 	int (*enable)(struct coresight_device *csdev, u32 mode, void *data);
-	void (*disable)(struct coresight_device *csdev);
+	int (*disable)(struct coresight_device *csdev);
 	void *(*alloc_buffer)(struct coresight_device *csdev, int cpu,
 			      void **pages, int nr_pages, bool overwrite);
 	void (*free_buffer)(void *config);