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SubjectRe: [RFC] firmware loader: retry _nowait requests when userhelper is not yet available

[ Adding more Cc's. ]

On 03/04/2012 01:52 AM, Christian Lamparter wrote:

> During resume, the userhelper might not be available. However for
> drivers which use the request_firmware_nowait interface, this will
> only lead to a pointless WARNING and a device which no longer works
> after the resume [since it couldn't get the firmware, because the
> userhelper was not available to take the request].
>
> In order to solve this "chicken or egg" dilemma, the code now
> retries _nowait requests at one second intervals until the
> "loading_timeout" time is up.
>
> ---
> I'm aware about the previous "request_firmware* in probe" discussions.
> Unfortunately, the hardware needs firmware so there is no other way
> around it. So please, I just wanted to know what the general opinion
> about the idea behind this patch is.
>
> Regards,
> Christian
>
> BTW: I'm not on the list, so please keep the 'CC'.
> ---
> drivers/base/firmware_class.c | 24 +++++++++++++++++++++++-
> 1 files changed, 23 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 6c9387d..9f70096 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -19,6 +19,7 @@
> #include <linux/kthread.h>
> #include <linux/highmem.h>
> #include <linux/firmware.h>
> +#include <linux/delay.h>
> #include <linux/slab.h>
>
> #define to_dev(obj) container_of(obj, struct device, kobj)
> @@ -535,6 +536,11 @@ static int _request_firmware(const struct firmware **firmware_p,
>
> read_lock_usermodehelper();
>
> + if (nowait && usermodehelper_is_disabled()) {
> + retval = -EBUSY;
> + goto out;
> + }
> +
> if (WARN_ON(usermodehelper_is_disabled())) {
> dev_err(device, "firmware: %s will not be loaded\n", name);
> retval = -EBUSY;
> @@ -633,7 +639,7 @@ static int request_firmware_work_func(void *arg)
> {
> struct firmware_work *fw_work = arg;
> const struct firmware *fw;
> - int ret;
> + int ret, timeout = loading_timeout;
>
> if (!arg) {
> WARN_ON(1);
> @@ -642,6 +648,22 @@ static int request_firmware_work_func(void *arg)
>
> ret = _request_firmware(&fw, fw_work->name, fw_work->device,
> fw_work->uevent, true);
> +
> + while (ret == -EBUSY) {
> + /*
> + * Try to retrieve the firmware within the loading timeout.
> + * To stick with the loading timeout convention from above:
> + * loading_timeout = 0 means 'try forever' as well.
> + */
> +
> + msleep(1000);
> + ret = _request_firmware(&fw, fw_work->name, fw_work->device,
> + fw_work->uevent, true);
> +
> + if (timeout != 0 && timeout-- == 1)

> + break;

> + };

> +

> fw_work->cont(fw, fw_work->context);
>
> module_put(fw_work->module);



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