On Tue, Jun 05, 2018 at 04:07:01PM -0500, Kim Phillips wrote: > Increment the refcnt for driver modules in current use by calling > module_get in coresight_build_path and module_put in release_path. > > This prevents driver modules from being unloaded when they are in use, > either in sysfs or perf mode.
Why does it matter? Shouldn't you be allowed to remove any module at any point in time, much like a networking driver? > > Cc: Mathieu Poirier <[email protected]> > Cc: Leo Yan <[email protected]> > Cc: Alexander Shishkin <[email protected]> > Cc: Randy Dunlap <[email protected]> > Cc: Suzuki K Poulose <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Cc: Russell King <[email protected]> > Signed-off-by: Kim Phillips <[email protected]> > --- > drivers/hwtracing/coresight/coresight.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/hwtracing/coresight/coresight.c > b/drivers/hwtracing/coresight/coresight.c > index 338f1719641c..1c941351f1d1 100644 > --- a/drivers/hwtracing/coresight/coresight.c > +++ b/drivers/hwtracing/coresight/coresight.c > @@ -465,6 +465,12 @@ static int _coresight_build_path(struct coresight_device > *csdev, > > node->csdev = csdev; > list_add(&node->link, path); > + > + if (!try_module_get(csdev->dev.parent->driver->owner)) { What is to keep parent->driver from going away right here? What keeps parent around? This feels very fragile to me, I don't see any locking anywhere around this code path to try to keep things in place. thanks, greg k-h
