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Date:   Tue, 5 Jan 2021 17:00:58 -0800
From:   Siddharth Gupta <>
To:     Greg KH <>
        Linux Kernel Mailing List <>,
        "" <>
Subject: Re: PROBLEM: Firmware loader fallback mechanism no longer works with

On 1/4/2021 10:36 PM, Greg KH wrote:
> On Mon, Jan 04, 2021 at 02:43:45PM -0800, Siddharth Gupta wrote:
>> Hi all,
>> With the introduction of the filesystem change "fs: don't allow splice
>> read/write without explicit ops"[1] the fallback mechanism of the firmware
>> loader[2] no longer works when using sendfile[3] from the userspace.
> What userspace program are you using to load firmware?
The userspace program is in the android userspace which listens to a 
uevent from the firmware loader and then loads the firmware using 
>   Are you not using the in-kernel firmware loader for some reason?
We have certain non-standard firmware paths that should not be added to 
the linux kernel, and the firmware_class.path only supports a single path.
>> Since the binary attributes don't support splice_{read,write} functions the
>> calls to splice_{read,write} used the default kernel_{read,write} functions.
>> With the above change this results in an -EINVAL return from
>> do_splice_from[4].
>> This essentially means that sendfile will not work for any binary attribute
>> in the sysfs.
> Have you tried fixing this with a patch much like what we did for the
> proc files that needed this?  If not, can you?
I am not aware of this fix, could you provide me a link for reference? I 
will try it out.
>> [1]:
>> [2]:
>> [3]:
>> [4]:
> kernel development is on, not github :)
I use it because it is easier on the eyes when looking at diffs :D
But I'll be sure to use from now on if that is what is 
> thanks,
> greg k-h


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