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SubjectRe: [PATCH 1/7] atomics/tty: add missing atomic_long_t * cast
On Tue, Jun 05, 2018 at 04:53:34PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 05, 2018 at 04:43:04PM +0200, Peter Zijlstra wrote:
>
> > I can make a proper patch, hold on.
>
> ---
> Subject: atomic/tty: Fix up atomic abuse in ldsem
>
> Mark found ldsem_cmpxchg() needed an (atomic_long_t *) cast to keep
> working after making the atomic_long interface type safe.
>
> Needing casts is bad form, which made me look at the code. There are no
> ld_semaphore::count users outside of these functions so there is no
> reason why it can not be an atomic_long_t in the first place, obviating
> the need for this cast.
>
> That also ensures the loads use atomic_long_read(), which implies (at
> least) READ_ONCE() in order to guarantee single-copy-atomic loads.
>
> When using atomic_long_try_cmpxchg() the ldsem_cmpxchg() wrapper gets
> very thin (the only difference is not changing *old on success, which
> most callers don't seem to care about).
>
> So rework the whole thing to use atomic_long_t and its accessors
> directly.
>
> While there, fixup all the horrible comment styles.
>
> Cc: Peter Hurley <peter@hurleysoftware.com>
> Reported-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Looks good, I'll queue this up after 4.18-rc1 is out, thanks.

greg k-h

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