linux-kernel - Re: [PATCH v3 06/13] epoll: introduce helpers for adding/removing events to uring

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Message-ID: <20190531095549.GB17637@hirez.programming.kicks-ass.net>
Date:   Fri, 31 May 2019 11:55:49 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Roman Penyaev <rpenyaev@...e.de>
Cc:     azat@...event.org, akpm@...ux-foundation.org,
        viro@...iv.linux.org.uk, torvalds@...ux-foundation.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 06/13] epoll: introduce helpers for adding/removing
 events to uring

On Thu, May 16, 2019 at 10:58:03AM +0200, Roman Penyaev wrote:
> +#define atomic_set_unless_zero(ptr, flags)			\
> +({								\
> +	typeof(ptr) _ptr = (ptr);				\
> +	typeof(flags) _flags = (flags);				\
> +	typeof(*_ptr) _old, _val = READ_ONCE(*_ptr);		\
> +								\
> +	for (;;) {						\
> +		if (!_val)					\
> +			break;					\
> +		_old = cmpxchg(_ptr, _val, _flags);		\
> +		if (_old == _val)				\
> +			break;					\
> +		_val = _old;					\
> +	}							\
> +	_val;							\
> +})

> +#define atomic_or_with_mask(ptr, flags, mask)			\
> +({								\
> +	typeof(ptr) _ptr = (ptr);				\
> +	typeof(flags) _flags = (flags);				\
> +	typeof(flags) _mask = (mask);				\
> +	typeof(*_ptr) _old, _new, _val = READ_ONCE(*_ptr);	\
> +								\
> +	for (;;) {						\
> +		_new = (_val & ~_mask) | _flags;		\
> +		_old = cmpxchg(_ptr, _val, _new);		\
> +		if (_old == _val)				\
> +			break;					\
> +		_val = _old;					\
> +	}							\
> +	_val;							\
> +})

Don't call them atomic_*() if they're not part of the atomic_t
interface.