Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Thu, 14 Nov 2019 10:15:30 +0100 | Subject | Re: [PATCH v1] driver core: Allow device link operations inside sync_state() |
| |
On Wed, Nov 13, 2019 at 3:36 AM Saravana Kannan <saravanak@google.com> wrote: > > Some sync_state() implementations might need to call APIs that in turn > make calls to device link APIs. So, do the sync_state() callbacks > without holding the device link lock. > > Signed-off-by: Saravana Kannan <saravanak@google.com> > --- > drivers/base/core.c | 63 +++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 55 insertions(+), 8 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index e6d3e6d485da..d396b0597c10 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -48,6 +48,8 @@ early_param("sysfs.deprecated", sysfs_deprecated_setup); > static LIST_HEAD(wait_for_suppliers); > static DEFINE_MUTEX(wfs_lock); > static LIST_HEAD(deferred_sync); > +static LIST_HEAD(sync_list); > +static DEFINE_MUTEX(sync_lock); > static unsigned int defer_sync_state_count = 1; > > #ifdef CONFIG_SRCU > @@ -695,7 +697,23 @@ int device_links_check_suppliers(struct device *dev) > return ret; > } > > -static void __device_links_supplier_sync_state(struct device *dev) > +/** __device_links_queue_sync_state - Queue a device for sync_state() callback > + * @dev: Device to call sync_state() on > + * > + * Queues a device for a sync_state() callback when the device links write lock > + * isn't held. This allows the sync_state() execution flow to use device links > + * APIs. The caller must ensure this function is called with > + * device_links_write_lock() held. > + * > + * This function does a get_device() to make sure the device is not freed while > + * on this list. > + * > + * So the caller must also ensure that device_links_flush_sync_list() is called > + * as soon as the caller releases device_links_write_lock(). This is necessary > + * to make sure the sync_state() is called in a timely fashion and the > + * put_device() is called on this device. > + */ > +static void __device_links_queue_sync_state(struct device *dev) > { > struct device_link *link; > > @@ -709,12 +727,35 @@ static void __device_links_supplier_sync_state(struct device *dev) > return; > } > > - if (dev->bus->sync_state) > - dev->bus->sync_state(dev); > - else if (dev->driver && dev->driver->sync_state) > - dev->driver->sync_state(dev); > - > dev->state_synced = true;
BTW, this should go into device_links_flush_sync_list() too, shouldn't it?
| |