linux-kernel - [PATCH v3 08/20] coresight: Properly address concurrency in sink::update() functions

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Date:   Wed,  3 Apr 2019 21:35:29 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     alexander.shishkin@...ux.intel.com, peterz@...radead.org,
        suzuki.poulose@....com, mike.leach@....com, leo.yan@...aro.org,
        coresight@...ts.linaro.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 08/20] coresight: Properly address concurrency in sink::update() functions

When operating in CPU-wide trace scenarios and working with an N:1
source/sink HW topology, update() functions need to be made atomic
in order to avoid racing with start and stop operations.

Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 drivers/hwtracing/coresight/coresight-etb10.c   | 4 +++-
 drivers/hwtracing/coresight/coresight-tmc-etf.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 52b7d95ab498..6b50e781dc57 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -413,7 +413,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
 	const u32 *barrier;
 	u32 read_ptr, write_ptr, capacity;
 	u32 status, read_data;
-	unsigned long offset, to_read;
+	unsigned long offset, to_read, flags;
 	struct cs_buffers *buf = sink_config;
 	struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
@@ -422,6 +422,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
 
 	capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS;
 
+	spin_lock_irqsave(&drvdata->spinlock, flags);
 	__etb_disable_hw(drvdata);
 	CS_UNLOCK(drvdata->base);
 
@@ -532,6 +533,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
 	}
 	__etb_enable_hw(drvdata);
 	CS_LOCK(drvdata->base);
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	return to_read;
 }
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 30f868676540..a38ad2b0d95a 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -413,7 +413,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
 	u32 *buf_ptr;
 	u64 read_ptr, write_ptr;
 	u32 status;
-	unsigned long offset, to_read;
+	unsigned long offset, to_read, flags;
 	struct cs_buffers *buf = sink_config;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
@@ -424,6 +424,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
 	if (WARN_ON_ONCE(drvdata->mode != CS_MODE_PERF))
 		return 0;
 
+	spin_lock_irqsave(&drvdata->spinlock, flags);
 	CS_UNLOCK(drvdata->base);
 
 	tmc_flush_and_stop(drvdata);
@@ -517,6 +518,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
 		to_read = buf->nr_pages << PAGE_SHIFT;
 	}
 	CS_LOCK(drvdata->base);
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	return to_read;
 }
-- 
2.17.1