Messages in this thread | | | From | Mark Rutland <> | Subject | [PATCHv7 00/11] thread_info: use helpers to snapshot thread flags | Date | Wed, 17 Nov 2021 16:30:38 +0000 |
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TIP folk (Peter?), I've been assuming this would go via the TIP tree. Are you happy to pick this up nowish, or as a fixup after the next -rc1? There have been no significant changes since v3 (aisde from the addition of the PPC fix for v7), and this has continued to apply cleanly since then (with no conflicts when rebasing up to v5.16-rc1).
If nothing else, it would be really nice to get the first patch (adding the accessors) merged, so that we can convert each architecture in turn.
Usual blurb below...
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
[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
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(-)
-- 2.11.0
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