On Thu, Jul 23, 2020 at 07:07:07PM +0800, Greg Kroah-Hartman wrote:
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?
try_module_get() returns bool which doesn't have error code.
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?
I'll fix in next revision.
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. I will fix it in next revision.
Thanks, Tingwei
thanks,
greg k-h