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

[Mathieu Poirier]

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.poir...@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poul...@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 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