WARNING: unhandled amd64-linux syscall: 315

Hi,

Valgrind shipped with focal does not support the sched_getattr and sched_setattr syscalls, resulting in output like

--1234-- WARNING: unhandled amd64-linux syscall: 315
--1234-- You may be able to write your own handler.
--1234-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--1234-- Nevertheless we consider this a bug. Please report
--1234-- it at http://valgrind.org/support/bug_reports.html.

This has been fixed upstream in the meanwhile.

Could it be possible to cherry pick 6323fd5bfd94c3f80e2ff44f16488e0172bd9a96 into valgrind shipped with focal? Lots of applications make use of those syscalls.

Commit: https://sourceware.org/git/?p=valgrind.git;a=commit;h=6323fd5bfd94c3f80e2ff44f16488e0172bd9a96
Upstream bug report: https://bugs.kde.org/show_bug.cgi?id=369029

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: valgrind 1:3.15.0-1ubuntu9.1
ProcVersionSignature: Ubuntu 5.4.0-58.64-generic 5.4.73
Uname: Linux 5.4.0-58-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.14
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Wed Dec 30 17:54:26 2020
InstallationDate: Installed on 2016-04-22 (1713 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
SourcePackage: valgrind
UpgradeStatus: Upgraded to focal on 2020-12-27 (3 days ago)