On Tue, Aug 27, 2019 at 05:31:58PM +0100, Will Deacon wrote: > Hi all, > > This is version two of the patches I previously posted here: > > https://lkml.kernel.org/r/[email protected] > > Changes since v1 include: > > * Avoid duplicate WARNs when incrementing from zero > * Some crude lktdm perf results to motivate the change: > > # perf stat -r 3 -B -- echo {ATOMIC,REFCOUNT}_TIMING > >/sys/kernel/debug/provoke-crash/DIRECT > > # arm64 > ATOMIC_TIMING: 46.50451 +- 0.00134 > seconds time elapsed ( +- 0.00% ) > REFCOUNT_TIMING (REFCOUNT_FULL, mainline): 77.57522 +- > 0.00982 seconds time elapsed ( +- 0.01% ) > REFCOUNT_TIMING (REFCOUNT_FULL, this series): 48.7181 +- 0.0256 > seconds time elapsed ( +- 0.05% ) > > # x86 > ATOMIC_TIMING: 31.6225 +- 0.0776 > seconds time elapsed ( +- 0.25% ) > REFCOUNT_TIMING (!REFCOUNT_FULL, mainline/x86 asm): 31.6689 +- 0.0901 > seconds time elapsed ( +- 0.28% ) > REFCOUNT_TIMING (REFCOUNT_FULL, mainline): 53.203 +- 0.138 > seconds time elapsed ( +- 0.26% ) > REFCOUNT_TIMING (REFCOUNT_FULL, this series): 31.7408 +- 0.0486 > seconds time elapsed ( +- 0.15% )
Nice improvements! :) Please consider the series: Reviewed-by: Kees Cook <[email protected]> -Kees > > Cheers, > > Will > > Cc: Kees Cook <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Elena Reshetova <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Ard Biesheuvel <[email protected]> > Cc: Hanjun Guo <[email protected]> > Cc: Jan Glauber <[email protected]> > > --->8 > > Will Deacon (6): > lib/refcount: Define constants for saturation and max refcount values > lib/refcount: Ensure integer operands are treated as signed > lib/refcount: Remove unused refcount_*_checked() variants > lib/refcount: Move bulk of REFCOUNT_FULL implementation into header > lib/refcount: Improve performance of generic REFCOUNT_FULL code > lib/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions > > drivers/misc/lkdtm/refcount.c | 8 -- > include/linux/refcount.h | 236 +++++++++++++++++++++++++++++++++++++---- > lib/refcount.c | 237 > +----------------------------------------- > 3 files changed, 218 insertions(+), 263 deletions(-) > > -- > 2.11.0 > -- Kees Cook
