diff options
Diffstat (limited to 'drivers/base/dd.c')
| -rw-r--r-- | drivers/base/dd.c | 48 |
1 files changed, 47 insertions, 1 deletions
diff --git a/drivers/base/dd.c b/drivers/base/dd.c index a641cf3ccad6..b605f734b882 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -55,6 +55,13 @@ static struct workqueue_struct *deferred_wq; static atomic_t deferred_trigger_count = ATOMIC_INIT(0); /* + * In some cases, like suspend to RAM or hibernation, It might be reasonable + * to prohibit probing of devices as it could be unsafe. + * Once defer_all_probes is true all drivers probes will be forcibly deferred. + */ +static bool defer_all_probes; + +/* * deferred_probe_work_func() - Retry probing devices in the active list. */ static void deferred_probe_work_func(struct work_struct *work) @@ -172,6 +179,30 @@ static void driver_deferred_probe_trigger(void) } /** + * device_block_probing() - Block/defere device's probes + * + * It will disable probing of devices and defer their probes instead. + */ +void device_block_probing(void) +{ + defer_all_probes = true; + /* sync with probes to avoid races. */ + wait_for_device_probe(); +} + +/** + * device_unblock_probing() - Unblock/enable device's probes + * + * It will restore normal behavior and trigger re-probing of deferred + * devices. + */ +void device_unblock_probing(void) +{ + defer_all_probes = false; + driver_deferred_probe_trigger(); +} + +/** * deferred_probe_initcall() - Enable probing of deferred devices * * We don't want to get in the way when the bulk of drivers are getting probed. @@ -277,9 +308,20 @@ static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); static int really_probe(struct device *dev, struct device_driver *drv) { - int ret = 0; + int ret = -EPROBE_DEFER; int local_trigger_count = atomic_read(&deferred_trigger_count); + if (defer_all_probes) { + /* + * Value of defer_all_probes can be set only by + * device_defer_all_probes_enable() which, in turn, will call + * wait_for_device_probe() right after that to avoid any races. + */ + dev_dbg(dev, "Driver %s force probe deferral\n", drv->name); + driver_deferred_probe_add(dev); + return ret; + } + atomic_inc(&probe_count); pr_debug("bus: '%s': %s: probing driver %s with device %s\n", drv->bus->name, __func__, drv->name, dev_name(dev)); @@ -393,6 +435,10 @@ int driver_probe_done(void) */ void wait_for_device_probe(void) { + /* wait for the deferred probe workqueue to finish */ + if (driver_deferred_probe_enable) + flush_workqueue(deferred_wq); + /* wait for the known devices to complete their probing */ wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); async_synchronize_full(); |