On Thu, Jul 23, 2020 at 12:27:48PM +0800, Tingwei Zhang wrote:
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.
Are you sure this works? Why is it needed at all? Why not just tear down the children properly when a module is removed so that you don't need this at all?
Signed-off-by: Tingwei Zhang tingwei@codeaurora.org
drivers/hwtracing/coresight/coresight.c | 27 +++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index b7151c5f81b1..17bc76ea86ae 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -640,7 +640,7 @@ struct coresight_device *coresight_get_sink_by_id(u32 id)
- 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; @@ -648,10 +648,25 @@ static void coresight_grab_device(struct coresight_device *csdev) struct coresight_device *child; child = csdev->pdata->conns[i].child_dev;
if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) {if (!try_module_get(child->dev.parent->driver->owner))
Why the child's parent? Why not the child itself?
goto err;
What about the error given to you here? Why throw that away?
pm_runtime_get_sync(child->dev.parent);
}- if (!try_module_get(csdev->dev.parent->driver->owner))
goto err;
You don't reduce the child's parent's driver owner module reference here?
Ugh, that's a horid sentence :(
pm_runtime_get_sync(csdev->dev.parent);
- 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)pm_runtime_put(child->dev.parent);- }
- return -ENODEV;
} /* @@ -663,12 +678,15 @@ static void coresight_drop_device(struct coresight_device *csdev) int i; pm_runtime_put(csdev->dev.parent);
- module_put(csdev->dev.parent->driver->owner); 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)
if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) { pm_runtime_put(child->dev.parent);module_put(child->dev.parent->driver->owner);}} @@ -721,7 +739,8 @@ static int _coresight_build_path(struct coresight_device *csdev, if (!node) return -ENOMEM;
- coresight_grab_device(csdev);
- if (coresight_grab_device(csdev))
return -ENODEV;
Why not return the error given to you?
thanks,
greg k-h