Messages in this thread | | | From | Mark Rutland <> | Subject | [PATCH v8 00/11] thread_info: use helpers to snapshot thread flags | Date | Mon, 29 Nov 2021 13:06:42 +0000 |
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This is a trivial fixup and resend of v7 due to a typo breaking the build on powerpc, as spotted by the kernel test robot:
https://lore.kernel.org/r/202111271105.v7pE3REd-lkp@intel.com
I've fixed that, and I've double-checked the series, build testing a few configs for all architectures for chieck the kernel.org crosstool page provides a GCC 10.3.0 binary. That hit some (unrelated) latent issues, but there are no new failrues introduced by this series.
Thomas, I'm hoping you'd be happy to pick this again.
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 snapshot 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
Since v3 [4]: * Rebase to v5.14-rc4
Since v4 [5]: * Rebase to v5.15-rc1 * Apply Acked-by / Tested-by tags
Since v5 [6]: * Fix trivial whitespace bug in x86 patch
Since v6 [7]: * Rebase to v5.16-rc1 * Fix new issue on PPC where thread flags could be discarded
Since v7 [8]: * Add missing `&` to use of set_bits()
[1] https://lore.kernel.org/r/20210609122001.18277-1-mark.rutland@arm.com [2] https://lore.kernel.org/r/87k0mvtgeb.fsf@mpe.ellerman.id.au [3] https://lore.kernel.org/r/20210621090602.16883-1-mark.rutland@arm.com [4] https://lore.kernel.org/r/20210713113842.2106-1-mark.rutland@arm.com [5] https://lore.kernel.org/r/20210803095428.17009-1-mark.rutland@arm.com [6] https://lore.kernel.org/r/20210914103027.53565-1-mark.rutland@arm.com [7] https://lore.kernel.org/lkml/20211022135643.7442-1-mark.rutland@arm.com [8] https://lore.kernel.org/lkml/20211117163050.53986-1-mark.rutland@arm.com/
Thanks, Mark.
Mark Rutland (11): 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: avoid discarding flags in system_call_exception() 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/entry-common.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 | 15 +++++++-------- arch/powerpc/kernel/ptrace/ptrace.c | 3 +-- arch/x86/kernel/process.c | 8 ++++---- arch/x86/kernel/process.h | 4 ++-- 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 +- 19 files changed, 46 insertions(+), 34 deletions(-)
-- 2.30.2
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