From d724f65218b994da234081df5dfe417c23802a65 Mon Sep 17 00:00:00 2001 From: James Clark Date: Mon, 29 Jan 2024 15:40:41 +0000 Subject: [PATCH] coresight: Add helper for atomically taking the device Now that mode is in struct coresight_device, this pattern can be wrapped in a helper. Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240129154050.569566-11-james.clark@arm.com Signed-off-by: Suzuki K Poulose --- drivers/hwtracing/coresight/coresight-etm3x-core.c | 8 +++----- drivers/hwtracing/coresight/coresight-etm4x-core.c | 8 +++----- drivers/hwtracing/coresight/coresight-stm.c | 8 +++----- include/linux/coresight.h | 11 +++++++++++ 4 files changed, 20 insertions(+), 15 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c index de53c3e8db29..c301f6a5f065 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c @@ -556,14 +556,12 @@ static int etm_enable(struct coresight_device *csdev, struct perf_event *event, enum cs_mode mode) { int ret; - u32 val; struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); - val = local_cmpxchg(&drvdata->csdev->mode, CS_MODE_DISABLED, mode); - - /* Someone is already using the tracer */ - if (val) + if (!coresight_take_mode(csdev, mode)) { + /* Someone is already using the tracer */ return -EBUSY; + } switch (mode) { case CS_MODE_SYSFS: diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 1c64b54459d7..572ac4a5e4ff 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -840,13 +840,11 @@ static int etm4_enable(struct coresight_device *csdev, struct perf_event *event, enum cs_mode mode) { int ret; - u32 val; - val = local_cmpxchg(&csdev->mode, CS_MODE_DISABLED, mode); - - /* Someone is already using the tracer */ - if (val) + if (!coresight_take_mode(csdev, mode)) { + /* Someone is already using the tracer */ return -EBUSY; + } switch (mode) { case CS_MODE_SYSFS: diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c index b2ccbe989ff8..ff578762f6bf 100644 --- a/drivers/hwtracing/coresight/coresight-stm.c +++ b/drivers/hwtracing/coresight/coresight-stm.c @@ -193,17 +193,15 @@ static void stm_enable_hw(struct stm_drvdata *drvdata) static int stm_enable(struct coresight_device *csdev, struct perf_event *event, enum cs_mode mode) { - u32 val; struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); if (mode != CS_MODE_SYSFS) return -EINVAL; - val = local_cmpxchg(&csdev->mode, CS_MODE_DISABLED, mode); - - /* Someone is already using the tracer */ - if (val) + if (!coresight_take_mode(csdev, mode)) { + /* Someone is already using the tracer */ return -EBUSY; + } pm_runtime_get_sync(csdev->dev.parent); diff --git a/include/linux/coresight.h b/include/linux/coresight.h index ecf4b8aecca8..414bcbbdaf62 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -580,6 +580,17 @@ static inline bool coresight_is_percpu_sink(struct coresight_device *csdev) (csdev->subtype.sink_subtype == CORESIGHT_DEV_SUBTYPE_SINK_PERCPU_SYSMEM); } +/* + * Atomically try to take the device and set a new mode. Returns true on + * success, false if the device is already taken by someone else. + */ +static inline bool coresight_take_mode(struct coresight_device *csdev, + enum cs_mode new_mode) +{ + return local_cmpxchg(&csdev->mode, CS_MODE_DISABLED, new_mode) == + CS_MODE_DISABLED; +} + extern struct coresight_device * coresight_register(struct coresight_desc *desc); extern void coresight_unregister(struct coresight_device *csdev);