On Tue, May 29, 2018 at 8:07 PM, Mark Rutland <mark.rutl...@arm.com> wrote: > This series scripts the generation of the various atomic headers, to > ensure that the various atomic APIs remain consistent, reducing the risk > of human error, and simplifying future rework. > > The series is based on my atomic API cleanup patches [1,2], and can be > found on my atomics/generated branch [3] on kernel.org. > > The first three patches are preparatory rework, with patch four > introducing the infrastructure. The final three patches migrate to > generated headers. The scripts themselves are mostly POSIX sh (modulo > local), without bashisms, and work in dash and bash. > > Per Linus request that it is possible to use git grep to inspect the > atomic headers [3], the headers are committed (and not generated by > kbuild). Since we now expand the fallback definitions inline, each > *should* be easier to find with grep. Each header also has a comment at > the top with a path to the script used to generate it. > > While the diff stat looks like a huge addition, the scripting comes in > at ~800 lines in total, including the fallback definitions, so we're > removing ~1000 lines of hand-written code. At the same time, we fill in > gaps in the atomic_long API, and the instrumented atomic wrappers. > > Longer-term, I think things could be simplified if we were to rework the > headers such that we have: > > * arch/*/include/asm/atomic.h providing arch_atomic_*(). > > * include/linux/atomic-raw.h building raw_atomic_*() atop of the > arch_atomic_*() definitions, filling in gaps in the API. Having > separate arch_ and raw_ namespaces would simplify the ifdeffery. > > * include/linux/atomic.h building atomic_*() atop of the raw_atomic_*() > definitions, complete with any instrumentation. Instrumenting at this > level would lower the instrumentation overhead, and would not require > any ifdeffery as the whole raw_atomic_*() API would be available. > > ... I've avoided this for the time being due to the necessary churn in > arch code. > > Thanks, > Mark.
Wow! Nice work! I can say that besides KASAN, we will need hooking into atomics for KMSAN and KTSAN in future. Without this it would be lots of manual work with possibility of copy-paste errors. > [1] https://lkml.kernel.org/r/20180529154346.3168-1-mark.rutl...@arm.com > [2] git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git > atomics/api-cleanup > [3] git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git > atomics/generated > [4] > https://lkml.kernel.org/r/ca+55afxju0op8qllu0n-rjhbs7gqslvd8jcyedgw6jezfn7...@mail.gmail.com > > Mark Rutland (7): > atomics/tty: add missing atomic_long_t * cast > atomics/treewide: rework ordering barriers > atomics: separate basic {cmp,}xchg() > atomics: add common header generation files > atomics: switch to generated fallbacks > atomics: switch to generated atomic-long > atomics: switch to generated instrumentation > > MAINTAINERS | 1 + > arch/alpha/include/asm/atomic.h | 8 +- > arch/powerpc/include/asm/atomic.h | 17 +- > arch/riscv/include/asm/atomic.h | 17 +- > drivers/tty/tty_ldsem.c | 2 +- > include/asm-generic/atomic-instrumented-atomic.h | 1629 ++++++++++++++++ > include/asm-generic/atomic-instrumented.h | 394 +--- > include/asm-generic/atomic-long.h | 1150 +++++++++-- > include/linux/atomic-fallback.h | 2223 > ++++++++++++++++++++++ > include/linux/atomic.h | 1244 +----------- > scripts/atomic/atomic-tbl.sh | 186 ++ > scripts/atomic/atomics.tbl | 41 + > scripts/atomic/fallbacks/acquire | 9 + > scripts/atomic/fallbacks/add_negative | 16 + > scripts/atomic/fallbacks/add_unless | 16 + > scripts/atomic/fallbacks/andnot | 7 + > scripts/atomic/fallbacks/dec | 7 + > scripts/atomic/fallbacks/dec_and_test | 15 + > scripts/atomic/fallbacks/dec_if_positive | 15 + > scripts/atomic/fallbacks/dec_unless_positive | 14 + > scripts/atomic/fallbacks/fence | 11 + > scripts/atomic/fallbacks/fetch_add_unless | 23 + > scripts/atomic/fallbacks/inc | 7 + > scripts/atomic/fallbacks/inc_and_test | 15 + > scripts/atomic/fallbacks/inc_not_zero | 14 + > scripts/atomic/fallbacks/inc_unless_negative | 14 + > scripts/atomic/fallbacks/read_acquire | 7 + > scripts/atomic/fallbacks/release | 8 + > scripts/atomic/fallbacks/set_release | 7 + > scripts/atomic/fallbacks/sub_and_test | 16 + > scripts/atomic/fallbacks/try_cmpxchg | 11 + > scripts/atomic/gen-atomic-fallback.sh | 144 ++ > scripts/atomic/gen-atomic-instrumented.sh | 122 ++ > scripts/atomic/gen-atomic-long.sh | 98 + > 34 files changed, 5671 insertions(+), 1837 deletions(-) > create mode 100644 include/asm-generic/atomic-instrumented-atomic.h > create mode 100644 include/linux/atomic-fallback.h > create mode 100755 scripts/atomic/atomic-tbl.sh > create mode 100644 scripts/atomic/atomics.tbl > create mode 100644 scripts/atomic/fallbacks/acquire > create mode 100644 scripts/atomic/fallbacks/add_negative > create mode 100644 scripts/atomic/fallbacks/add_unless > create mode 100644 scripts/atomic/fallbacks/andnot > create mode 100644 scripts/atomic/fallbacks/dec > create mode 100644 scripts/atomic/fallbacks/dec_and_test > create mode 100644 scripts/atomic/fallbacks/dec_if_positive > create mode 100644 scripts/atomic/fallbacks/dec_unless_positive > create mode 100644 scripts/atomic/fallbacks/fence > create mode 100644 scripts/atomic/fallbacks/fetch_add_unless > create mode 100644 scripts/atomic/fallbacks/inc > create mode 100644 scripts/atomic/fallbacks/inc_and_test > create mode 100644 scripts/atomic/fallbacks/inc_not_zero > create mode 100644 scripts/atomic/fallbacks/inc_unless_negative > create mode 100644 scripts/atomic/fallbacks/read_acquire > create mode 100644 scripts/atomic/fallbacks/release > create mode 100644 scripts/atomic/fallbacks/set_release > create mode 100644 scripts/atomic/fallbacks/sub_and_test > create mode 100644 scripts/atomic/fallbacks/try_cmpxchg > create mode 100755 scripts/atomic/gen-atomic-fallback.sh > create mode 100755 scripts/atomic/gen-atomic-instrumented.sh > create mode 100755 scripts/atomic/gen-atomic-long.sh > > -- > 2.11.0 >
