On Wed, Aug 05, 2020 at 11:43:36PM +0800, Suzuki K Poulose wrote:
On 08/05/2020 03:54 AM, Tingwei Zhang wrote:
From: Kim Phillips kim.phillips@arm.com
Allow to build coresight-etb10 as a module, for ease of development.
- Kconfig becomes a tristate, to allow =m
- add an etb_remove function, for module unload
- add a MODULE_DEVICE_TABLE for autoloading on boot
Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Leo Yan leo.yan@linaro.org Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Randy Dunlap rdunlap@infradead.org Cc: Suzuki K Poulose Suzuki.Poulose@arm.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Russell King linux@armlinux.org.uk Signed-off-by: Kim Phillips kim.phillips@arm.com Signed-off-by: Tingwei Zhang tingwei@codeaurora.org Tested-by: Mike Leach mike.leach@linaro.org
drivers/hwtracing/coresight/Kconfig | 5 ++++- drivers/hwtracing/coresight/coresight-etb10.c | 20 ++++++++++++++++++- 2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig index d6e107bbd30b..996d84a1edb8 100644 --- a/drivers/hwtracing/coresight/Kconfig +++ b/drivers/hwtracing/coresight/Kconfig @@ -57,13 +57,16 @@ config CORESIGHT_SINK_TPIU the on-board coresight memory can handle.
config CORESIGHT_SINK_ETBV10
- bool "Coresight ETBv1.0 driver"
- tristate "Coresight ETBv1.0 driver" depends on CORESIGHT_LINKS_AND_SINKS help This enables support for the Embedded Trace Buffer version 1.0 driver that complies with the generic implementation of the component
without special enhancement or added features.
To compile this driver as a module, choose M here: themodule will be called coresight-etb10.config CORESIGHT_SOURCE_ETM3X tristate "CoreSight Embedded Trace Macrocell 3.x driver" depends on !ARM64 diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c index 04ee9cda988d..b40756497c9a 100644 --- a/drivers/hwtracing/coresight/coresight-etb10.c +++ b/drivers/hwtracing/coresight/coresight-etb10.c @@ -801,6 +801,16 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id) return ret; }
+static int __exit etb_remove(struct amba_device *adev) +{
- struct etb_drvdata *drvdata = dev_get_drvdata(&adev->dev);
- misc_deregister(&drvdata->miscdev);
- coresight_unregister(drvdata->csdev);
- return 0;
+}
I am worried about the dangling reference via the misc device to the drvdata. Not sure, if we need to grab the reference the module for each open fd on the misc device. The misc device infrastructure doesn't seem to do any of this implicitly. This is something worth checking. I will see if I can trigger this.
Misc device is one char device. cdev_get() is called in chrdev_open() to grab reference of module. Look like we are safe here.
Thanks, Tingwei
i.e,
CPU 0: CPU1:
open("/dev/etb") etb_open() ... etb_remove() { .. coresight_unregister() }
read() etb_read() deal with free'd drvdata ?
Cheers Suzuki