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    Subject[RFC] firmware load: defer request_firmware during early boot and resume
    From
    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.

    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..4fe742f 100644
    --- a/drivers/base/firmware_class.c
    +++ b/drivers/base/firmware_class.c
    @@ -593,6 +593,9 @@ request_firmware(const struct firmware
    **firmware_p, const char *name,
    if (IS_ERR_OR_NULL(fw_priv))
    return PTR_RET(fw_priv);

    + if (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..237eae1 100644
    --- a/init/main.c
    +++ b/init/main.c
    @@ -809,6 +809,8 @@ static noinline int init_post(void)
    current->signal->flags |= SIGNAL_UNKILLABLE;
    flush_delayed_fput();

    + 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..dbf6ffb 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 +304,10 @@ static int enter_state(suspend_state_t state)
    Finish:
    pr_debug("PM: Finishing wakeup.\n");
    suspend_finish();
    +
    + system_state = SYSTEM_RUNNING;
    + driver_deferred_probe_trigger();
    +
    Unlock:
    mutex_unlock(&pm_mutex);
    return error;

    Thanks,
    --
    Ming Lei


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