[PATCH v3 00/10] thread_info: use helpers to snapshot thread flags
From: Mark Rutland
Date: Tue Jul 13 2021 - 07:39:04 EST
[apologies for the dupliate cover letter; I messed up the LKML address when I
first tried to send this out]
As thread_info::flags scan be manipulated by remote threads, it is
necessary to use atomics or READ_ONCE() to ensure that code manipulates
a consistent snapshot, but we open-code plain accesses to
thread_info::flags across the kernel tree.
Generally we get away with this, but tools like KCSAN legitimately warn
that there is a data-race, and this is potentially fragile with compiler
optimizations, LTO, etc.
These patches introduce new helpers to snahpshot the thread flags, with
the intent being that these should replace all plain accesses.
Since v1 [1]:
* Drop RFC
* Make read_ti_thread_flags() __always_inline
* Clarify commit messages
* Fix typo in arm64 patch
* Accumulate Reviewed-by / Acked-by tags
* Drop powerpc patch to avoid potential conflicts (per [2])
Since v2 [3]:
* Rebase to v5.14-rc1
* Reinstate powerpc patch
[1] https://lore.kernel.org/r/20210609122001.18277-1-mark.rutland@xxxxxxx
[2] https://lore.kernel.org/r/87k0mvtgeb.fsf@xxxxxxxxxxxxxxxxxx
[3] https://lore.kernel.org/r/20210621090602.16883-1-mark.rutland@xxxxxxx
Thanks,
Mark.
Mark Rutland (10):
thread_info: add helpers to snapshot thread flags
entry: snapshot thread flags
sched: snapshot thread flags
alpha: snapshot thread flags
arm: snapshot thread flags
arm64: snapshot thread flags
microblaze: snapshot thread flags
openrisc: snapshot thread flags
powerpc: snapshot thread flags
x86: snapshot thread flags
arch/alpha/kernel/signal.c | 2 +-
arch/arm/kernel/signal.c | 2 +-
arch/arm/mm/alignment.c | 2 +-
arch/arm64/kernel/ptrace.c | 4 ++--
arch/arm64/kernel/signal.c | 2 +-
arch/arm64/kernel/syscall.c | 4 ++--
arch/microblaze/kernel/signal.c | 2 +-
arch/openrisc/kernel/signal.c | 2 +-
arch/powerpc/kernel/interrupt.c | 13 ++++++-------
arch/powerpc/kernel/ptrace/ptrace.c | 3 +--
arch/x86/kernel/process.c | 8 ++++----
arch/x86/kernel/process.h | 6 +++---
arch/x86/mm/tlb.c | 2 +-
include/linux/entry-kvm.h | 2 +-
include/linux/thread_info.h | 14 ++++++++++++++
kernel/entry/common.c | 4 ++--
kernel/entry/kvm.c | 4 ++--
kernel/sched/core.c | 2 +-
18 files changed, 45 insertions(+), 33 deletions(-)
--
2.11.0