On Tue, Oct 09, 2012 at 01:36:28PM -0700, Josh Triplett wrote:
> On Tue, Oct 09, 2012 at 01:06:37PM -0700, Andrew Morton wrote:
> > On Sun, 7 Oct 2012 19:06:10 -0700
> > Josh Triplett <j...@joshtriplett.org> wrote:
> >
> > > linux/compiler.h has macros to denote functions that acquire or release
> > > locks, but not to denote functions called with a lock held that return
> > > with the lock still held. Add a __must_hold macro to cover that case.
> >
> > hum. How does this work? Any code examples and sample sparse output?
> > Does it apply to all lock types, etc?
>
> It applies to all the same lock types that __acquires and __releases
> apply to: currently everything since Sparse doesn't actually do anything
> with the parameter, just the context value.
>
> Various code examples already exist in the kernel tree for __acquires
> and __releases, and the mailing list contains many reports of the Sparse
> context warnings.
>
> Just as __acquires and __release annotate functions that return with a
> lock acquired and get called with a lock that they drop (respectively),
> __must_hold annotates a function called with a lock acquired that return
> with that lock still acquired.
>
> > IOW, where is all this stuff documented?
>
> The Sparse manpage documents the context bits reasonably well. Other
> than that, nowhere that I know of other than the Sparse testsuite and
> the source trees of projects like Linux that use Sparse.
The kernel specific macros should be documented in:
Documentation/sparse.txt
For now only __bitwise is documentd, but when we introduce new
sparse annotation macros in the kernel the documentation should
be mandatory.
Sam
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