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Subject[PATCH 20/32] coresight: Properly address concurrency in sink::update() functions
Date
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@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>
---
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 6b73bc2e0dbd..00d664c6a401 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -405,7 +405,7 @@ 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);

@@ -414,6 +414,7 @@ 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);

@@ -524,6 +525,7 @@ 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
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