On Wed, Dec 5, 2018 at 9:25 AM Alexander Duyck <[email protected]> wrote: > > Add an additional bit flag to the device struct named "dead". > > This additional flag provides a guarantee that when a device_del is > executed on a given interface an async worker will not attempt to attach > the driver following the earlier device_del call. Previously this > guarantee was not present and could result in the device_del call > attempting to remove a driver from an interface only to have the async > worker attempt to probe the driver later when it finally completes the > asynchronous probe call. > > Signed-off-by: Alexander Duyck <[email protected]> > --- > drivers/base/core.c | 11 +++++++++++ > drivers/base/dd.c | 8 ++++++-- > include/linux/device.h | 5 +++++ > 3 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index f3e6ca4170b4..70358327303b 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -2075,6 +2075,17 @@ void device_del(struct device *dev) > struct kobject *glue_dir = NULL; > struct class_interface *class_intf; > > + /* > + * Hold the device lock and set the "dead" flag to guarantee that > + * the update behavior is consistent with the other bitfields near > + * it and that we cannot have an asynchronous probe routine trying > + * to run while we are tearing out the bus/class/sysfs from > + * underneath the device. > + */ > + device_lock(dev); > + dev->dead = true; > + device_unlock(dev); > + > /* Notify clients of device removal. This call must come > * before dpm_sysfs_remove(). > */ > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 88713f182086..3bb8c3e0f3da 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -774,6 +774,10 @@ static void __device_attach_async_helper(void *_dev, > async_cookie_t cookie) > > device_lock(dev); > > + /* device is or has been removed from the bus, just bail out */ > + if (dev->dead) > + goto out_unlock; > +
What do you think about moving this check into __device_attach_driver() alongside all the other checks? That way we also get ->dead checking through the __device_attach() path. ...and after that maybe it could be made a common helper (dev_driver_checks()?) shared between __device_attach_driver() and __driver_attach() to reduce some duplication.
