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
sendfile[1].
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]: https://github.com/torvalds/linux/commit/36e2c7421f02a22f71c9283e55fdb672a9eb58e7#diff-70c49af2ed5805fc1406ed6e6532d6a029ada1abd90cca6442711b9cecd4d523
[2]: https://github.com/torvalds/linux/blob/master/drivers/base/firmware_loader/main.c#L831
[3]: https://github.com/torvalds/linux/blob/master/fs/read_write.c#L1257
[4]: https://github.com/torvalds/linux/blob/master/fs/splice.c#L753
kernel development is on git.kernel.org, not github :)
I use it because it is easier on the eyes when looking at diffs :D
But I'll be sure to use git.kernel.org from now on if that is what is
preferred!
thanks,
greg k-h
Thanks,
Sid
[1]:
https://android.googlesource.com/platform/system/core/+/refs/heads/master/init/firmware_handler.cpp#55
