On Saturday, July 21, 2012, Ming Lei wrote: > CC guys who discussed the problem in the below link in Jan. : > > http://marc.info/?t=132528956000002&r=10&w=2 > > On Fri, Jul 20, 2012 at 8:33 PM, Ming Lei <tom.leiming@xxxxxxxxx> wrote: > > The RFC patch is just for discussing if the idea of deferring > > request_firmware is doable for addressing the issue of > > request_firmware in resume path, which is caused by driver > > unbind/rebind during resume. > > > > At least usb bus is involved in such things, one driver may be > > unbound and rebound in resume path at several situations, and > > request_firmware is often called inside probe(). > > > > Also the idea should be helpful for other hotplug buses too, > > at least there was the similar problem report on pcmcia bus. > > Looks it works well in my two test cases: one is to call request_firmware > in early boot(initcall), another one is to call request_firmware in probe() > of resume path(caused by unbind & rebind). And without the patch, both > two request_firmware return failure and can't complete the loading. And that's precisely why you're not supposed to use request_firmware() in those two situations. My opinion is that, at least for the suspend/hibernate case, the firmware data should be loaded into memory before suspend (e.g. using a PM notifier) and released only after the corresponding resume (or suspend failure), so that it's present in memory during the entire suspend-resume cycle. The early bood situation may be handled through deferred probing. Thanks, Rafael > V1: > only defer handling the requests called from probe() > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 6cd2c6c..fb02eff 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -123,7 +123,7 @@ static bool driver_deferred_probe_enable = false; > * list and schedules the deferred probe workqueue to process them. It > * should be called anytime a driver is successfully bound to a device. > */ > -static void driver_deferred_probe_trigger(void) > +void driver_deferred_probe_trigger(void) > { > if (!driver_deferred_probe_enable) > return; > @@ -144,6 +144,7 @@ static void driver_deferred_probe_trigger(void) > */ > queue_work(deferred_wq, &deferred_probe_work); > } > +EXPORT_SYMBOL_GPL(driver_deferred_probe_trigger); > > /** > * deferred_probe_initcall() - Enable probing of deferred devices > diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c > index 5401814..1b13536 100644 > --- a/drivers/base/firmware_class.c > +++ b/drivers/base/firmware_class.c > @@ -21,6 +21,7 @@ > #include <linux/firmware.h> > #include <linux/slab.h> > #include <linux/sched.h> > +#include "base.h" > > #define to_dev(obj) container_of(obj, struct device, kobj) > > @@ -593,6 +594,11 @@ request_firmware(const struct firmware > **firmware_p, const char *name, > if (IS_ERR_OR_NULL(fw_priv)) > return PTR_RET(fw_priv); > > + /* only defer handling the requests called from probe() */ > + if (!klist_node_attached(&device->p->knode_driver) && > + system_state != SYSTEM_RUNNING) > + return -EPROBE_DEFER; > + > ret = usermodehelper_read_trylock(); > if (WARN_ON(ret)) { > dev_err(device, "firmware: %s will not be loaded\n", name); > diff --git a/include/linux/device.h b/include/linux/device.h > index d0e4d99..a63d3171 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -244,7 +244,7 @@ extern struct device_driver *driver_find(const char *name, > struct bus_type *bus); > extern int driver_probe_done(void); > extern void wait_for_device_probe(void); > - > +extern void driver_deferred_probe_trigger(void); > > /* sysfs interface for exporting driver attributes */ > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index e07f5e0..c8d74c6 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -378,6 +378,7 @@ extern enum system_states { > SYSTEM_POWER_OFF, > SYSTEM_RESTART, > SYSTEM_SUSPEND_DISK, > + SYSTEM_SUSPEND, > } system_state; > > #define TAINT_PROPRIETARY_MODULE 0 > diff --git a/init/main.c b/init/main.c > index e60679d..02fc1c2 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -809,6 +809,9 @@ static noinline int init_post(void) > current->signal->flags |= SIGNAL_UNKILLABLE; > flush_delayed_fput(); > > + /* defer handling request_firmware in probe of initcall path */ > + driver_deferred_probe_trigger(); > + > if (ramdisk_execute_command) { > run_init_process(ramdisk_execute_command); > printk(KERN_WARNING "Failed to execute %s\n", > diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c > index 1da39ea..61c723f 100644 > --- a/kernel/power/suspend.c > +++ b/kernel/power/suspend.c > @@ -224,6 +224,9 @@ int suspend_devices_and_enter(suspend_state_t state) > goto Recover_platform; > } > suspend_test_finish("suspend devices"); > + > + system_state = SYSTEM_SUSPEND; > + > if (suspend_test(TEST_DEVICES)) > goto Recover_platform; > > @@ -301,6 +304,12 @@ static int enter_state(suspend_state_t state) > Finish: > pr_debug("PM: Finishing wakeup.\n"); > suspend_finish(); > + > + system_state = SYSTEM_RUNNING; > + > + /* defer handling request_firmware in probe of resume path */ > + driver_deferred_probe_trigger(); > + > Unlock: > mutex_unlock(&pm_mutex); > return error; > > > > Thanks, > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
