When coresight device is in an active session, driver module of that device should not be removed. Use try_get_module() in coresight_grab_device() to prevent module to be unloaded. Use get_device()/put_device() to protect device data in the middle of active session.
Signed-off-by: Tingwei Zhang tingwei@codeaurora.org Tested-by: Mike Leach mike.leach@linaro.org Suggested-by: Suzuki K Poulose suzuki.poulose@arm.com --- drivers/hwtracing/coresight/coresight.c | 60 ++++++++++++++++++++++--- 1 file changed, 53 insertions(+), 7 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index cd17aea6b50d..b040d4421f84 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -633,13 +633,45 @@ struct coresight_device *coresight_get_sink_by_id(u32 id) return dev ? to_coresight_device(dev) : NULL; }
+/** + * coresight_get_ref- Helper function to increase reference count to module + * and device. + * Return true in successful case and power up the device. + * Return false when failed to get reference of module. + */ +static inline bool coresight_get_ref(struct coresight_device *csdev) +{ + struct device *dev = csdev->dev.parent; + + /* Make sure the driver can't be removed */ + if (!try_module_get(dev->driver->owner)) + return false; + /* Make sure the device can't go away */ + get_device(dev); + pm_runtime_get_sync(dev); + return true; +} + +/** + * coresight_put_ref- Helper function to decrease reference count to module + * and device. Power off the device. + */ +static inline void coresight_put_ref(struct coresight_device *csdev) +{ + struct device *dev = csdev->dev.parent; + + pm_runtime_put(dev); + put_device(dev); + module_put(dev->driver->owner); +} + /* * coresight_grab_device - Power up this device and any of the helper * devices connected to it for trace operation. Since the helper devices * don't appear on the trace path, they should be handled along with the * the master device. */ -static void coresight_grab_device(struct coresight_device *csdev) +static int coresight_grab_device(struct coresight_device *csdev) { int i;
@@ -648,9 +680,20 @@ static void coresight_grab_device(struct coresight_device *csdev)
child = csdev->pdata->conns[i].child_dev; if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) - pm_runtime_get_sync(child->dev.parent); + if (!coresight_get_ref(child)) + goto err; + } + if (coresight_get_ref(csdev)) + return 0; +err: + for (i--; i >= 0; i--) { + struct coresight_device *child; + + child = csdev->pdata->conns[i].child_dev; + if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) + coresight_put_ref(child); } - pm_runtime_get_sync(csdev->dev.parent); + return -ENODEV; }
/* @@ -661,13 +704,13 @@ static void coresight_drop_device(struct coresight_device *csdev) { int i;
- pm_runtime_put(csdev->dev.parent); + coresight_put_ref(csdev); for (i = 0; i < csdev->pdata->nr_outport; i++) { struct coresight_device *child;
child = csdev->pdata->conns[i].child_dev; if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) - pm_runtime_put(child->dev.parent); + coresight_put_ref(child); } }
@@ -686,7 +729,7 @@ static int _coresight_build_path(struct coresight_device *csdev, struct coresight_device *sink, struct list_head *path) { - int i; + int i, ret; bool found = false; struct coresight_node *node;
@@ -716,11 +759,14 @@ static int _coresight_build_path(struct coresight_device *csdev, * is tell the PM runtime core we need this element and add a node * for it. */ + ret = coresight_grab_device(csdev); + if (ret) + return ret; + node = kzalloc(sizeof(struct coresight_node), GFP_KERNEL); if (!node) return -ENOMEM;
- coresight_grab_device(csdev); node->csdev = csdev; list_add(&node->link, path);