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 --- drivers/hwtracing/coresight/coresight-etb10.c | 21 ++++++++++---- .../hwtracing/coresight/coresight-tmc-etf.c | 21 +++++++++++--- .../hwtracing/coresight/coresight-tmc-etr.c | 19 +++++++++++-- drivers/hwtracing/coresight/coresight-tpiu.c | 6 +++- drivers/hwtracing/coresight/coresight.c | 28 +++++++++---------- 5 files changed, 66 insertions(+), 29 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c index 71c2a3cdb866..5af50a852e87 100644 --- a/drivers/hwtracing/coresight/coresight-etb10.c +++ b/drivers/hwtracing/coresight/coresight-etb10.c @@ -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> @@ -159,14 +160,15 @@ 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; @@ -196,8 +198,10 @@ 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); @@ -332,6 +336,11 @@ 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); diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index d4213e7c2c45..d50a608a60f1 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -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); diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index 33501777038a..f90bca971367 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -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> @@ -1124,8 +1125,10 @@ 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, @@ -1138,8 +1141,10 @@ 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);
@@ -1370,8 +1375,10 @@ 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); @@ -1398,11 +1405,17 @@ 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); diff --git a/drivers/hwtracing/coresight/coresight-tpiu.c b/drivers/hwtracing/coresight/coresight-tpiu.c index 0d13da1b9df1..7acbeffcc137 100644 --- a/drivers/hwtracing/coresight/coresight-tpiu.c +++ b/drivers/hwtracing/coresight/coresight-tpiu.c @@ -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"); diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index 13eda4693f81..19ba121d7451 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -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,