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Subject[RFC PATCH 0/6] Simplify setting thread flags to a particular value
Date
There are a number of bits of code sprinkled around the kernel to
set a thread flag if a certain condition is true, and clear it
otherwise.

To help make those call sites terser and less cumbersome, this
patch adds a new family of thread flag manipulators

update*_thread_flag([...,] flag, cond)

See patch 1 for details.

Reviewers please pay close attention to accidental conversion of
set_tsk_thread_flag() to set_thread_flag() for example, and accidental
inversion of conditions. I'm pretty sure neither happens, but
build-testing can't pick these up.

Build-tested on x86 and the explicitly patched architectures (defconfig
and multi_v7_defconfig for arm, defconfig for arm64, mips, powerpc,
sparc).

Boot-tested on arm64, with some context-switch stress tests that depend
on correct maintenance of TIF_FOREIGN_FPSTATE.


Background rationale:

I've found myself coding this idiom a few times now and would like to
stop duplicating it. Using an ungainly lash-up of sed and grep I tried
to find other users of the same idiom without too many false positives,
and there while there aren't a huge number it seemed enough to be worth
having a go at a simple cleanup.

The core changes are in the first patch; other changes are split
per-arch.


Dave Martin (6):
thread_info: Add update_thread_flag() helpers
ARM: Use update_thread_flag()
arm64: Use update{,_tsk}_thread_flag()
MIPS: Use update{,_tsk}_thread_flag()
powerpc: Use update_thread_flag()
sparc: Use update_thread_flag()

arch/arm/kernel/elf.c | 9 +++------
arch/arm64/kernel/fpsimd.c | 19 +++++++------------
arch/mips/kernel/elf.c | 10 ++--------
arch/mips/kernel/process.c | 15 ++++++---------
arch/mips/kernel/ptrace.c | 5 +----
arch/mips/kernel/syscall.c | 10 ++--------
arch/powerpc/include/asm/elf.h | 10 ++--------
arch/sparc/include/asm/elf_64.h | 5 +----
include/linux/sched.h | 6 ++++++
include/linux/thread_info.h | 11 +++++++++++
include/trace/syscall.h | 6 ++----
kernel/ptrace.c | 13 +++++--------
12 files changed, 48 insertions(+), 71 deletions(-)

--
2.1.4

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