Messages in this thread | | | Date | Wed, 13 Feb 2019 15:56:46 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 02/32] locking/lockdep: Introduce struct lock_usage |
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On Tue, Feb 12, 2019 at 09:38:42AM -0800, Linus Torvalds wrote: > On Tue, Feb 12, 2019 at 9:14 AM Frederic Weisbecker <frederic@kernel.org> wrote: > > > > +static u64 lock_usage_mask(struct lock_usage *usage) > > +{ > > + return BIT(usage->bit); > > +} > > More insane "u64" - and it's *incorrect* too. > > #define BIT(nr) (1UL << (nr)) > > fundamentally means that "BIT()" can only work on up to "unsigned long". > > So this odd use of u64 seems to be a disease. It only uses more memory > (and more CPU) for no obvious reason. > > u64 is not some "default type". It's expensive and shouldn't be used > unless you have a *reason* for it.
Right, I'll simply move "[PATCH 03/32] locking/lockdep: Convert usage_mask to u64" at the first position and follow up on that to justify its use.
Thanks.
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