Messages in this thread | | | Subject | Re: [PATCH v6 5/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file | From | Joe Perches <> | Date | Fri, 27 Sep 2013 07:05:00 -0700 |
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On Fri, 2013-09-27 at 15:48 +0200, Peter Zijlstra wrote: > On Fri, Sep 27, 2013 at 06:44:55AM -0700, Joe Perches wrote: > > It's a CHK test, so it's only tested with --strict > > > > $ scripts/checkpatch.pl -f --strict kernel/mutex.c 2>&1 | grep memory > > CHECK: memory barrier without comment > > CHECK: memory barrier without comment > > > > It could be changed to WARN so it's always on. > > Yes please, we can't be too careful with memory barriers.
I'll send the patch separately.
It seems a pretty noisy test. There are 13 hits just in arch/x86/kernel/
$ ./scripts/checkpatch.pl -f arch/x86/kernel/*.c | grep -A3 "memory barrier" WARNING: memory barrier without comment #685: FILE: x86/kernel/alternative.c:685: + smp_wmb();
-- WARNING: memory barrier without comment #401: FILE: x86/kernel/kvm.c:401: + rmb();
WARNING: memory barrier without comment #403: FILE: x86/kernel/kvm.c:403: + rmb();
-- WARNING: memory barrier without comment #702: FILE: x86/kernel/kvm.c:702: + smp_wmb();
WARNING: memory barrier without comment #704: FILE: x86/kernel/kvm.c:704: + smp_wmb();
-- WARNING: memory barrier without comment #62: FILE: x86/kernel/ldt.c:62: + wmb();
WARNING: memory barrier without comment #64: FILE: x86/kernel/ldt.c:64: + wmb();
-- WARNING: memory barrier without comment #204: FILE: x86/kernel/smpboot.c:204: + wmb();
WARNING: memory barrier without comment #265: FILE: x86/kernel/smpboot.c:265: + wmb();
-- WARNING: memory barrier without comment #557: FILE: x86/kernel/smpboot.c:557: + mb();
-- WARNING: memory barrier without comment #1065: FILE: x86/kernel/smpboot.c:1065: + mb();
-- WARNING: memory barrier without comment #1321: FILE: x86/kernel/smpboot.c:1321: + mb();
WARNING: memory barrier without comment #1399: FILE: x86/kernel/smpboot.c:1399: + mb();
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