Subject: Re: [PATCH v3 2/7] include: add setbits_leXX/clrbits_leXX/clrsetbits_leXX in linux/setbits.h

From: Jakub Kicinski <[email-masked]>
Date: Wed, 24 Oct 2018 15:46:13 -0700

On Wed, 24 Oct 2018 07:35:48 +0000, Corentin Labbe wrote:
> This patch adds setbits_le32/clrbits_le32/clrsetbits_le32 and
> setbits_le64/clrbits_le64/clrsetbits_le64 in linux/setbits.h header.
> 
> Signed-off-by: Corentin Labbe <[email-masked]>

Did you have a look at all the functions defined in bitfield.h?
(including the magic macro-generated ones?)  Perhaps those could be
used here?

I also share the concerns about the non-atomic RMW.  Obviously correct
beats short IMHO.

> diff --git a/include/linux/setbits.h b/include/linux/setbits.h
> new file mode 100644
> index 000000000000..c82faf8d7fe4
> --- /dev/null
> +++ b/include/linux/setbits.h
> @@ -0,0 +1,84 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __LINUX_SETBITS_H
> +#define __LINUX_SETBITS_H
> +
> +#include <linux/io.h>
> +
> +#define __setbits(rfn, wfn, addr, set) wfn((rfn(addr) | (set)), addr)
> +#define __clrbits(rfn, wfn, addr, mask) wfn((rfn(addr) & ~(mask)), addr)
> +#define __clrsetbits(rfn, wfn, addr, mask, set) wfn(((rfn(addr) & ~(mask)) | (set)), addr)
> +#define __setclrbits(rfn, wfn, addr, mask, set) wfn(((rfn(addr) | (set)) & ~(mask)), addr)
> +
> +#ifndef setbits_le32
> +#define setbits_le32(addr, set) __setbits(readl, writel, addr, set)
> +#endif
> +#ifndef setbits_le32_relaxed
> +#define setbits_le32_relaxed(addr, set) __setbits(readl_relaxed, writel_relaxed, \
> +					       addr, set)
> +#endif
> +
> +#ifndef clrbits_le32
> +#define clrbits_le32(addr, mask) __clrbits(readl, writel, addr, mask)
> +#endif
> +#ifndef clrbits_le32_relaxed
> +#define clrbits_le32_relaxed(addr, mask) __clrbits(readl_relaxed, writel_relaxed, \
> +						addr, mask)
> +#endif
> +
> +#ifndef clrsetbits_le32
> +#define clrsetbits_le32(addr, mask, set) __clrsetbits(readl, writel, addr, mask, set)
> +#endif
> +#ifndef clrsetbits_le32_relaxed
> +#define clrsetbits_le32_relaxed(addr, mask, set) __clrsetbits(readl_relaxed, \
> +							   writel_relaxed, \
> +							   addr, mask, set)
> +#endif
> +
> +#ifndef setclrbits_le32
> +#define setclrbits_le32(addr, mask, set) __setclrbits(readl, writel, addr, mask, set)
> +#endif
> +#ifndef setclrbits_le32_relaxed
> +#define setclrbits_le32_relaxed(addr, mask, set) __setclrbits(readl_relaxed, \
> +							   writel_relaxed, \
> +							   addr, mask, set)
> +#endif
> +
> +/* We cannot use CONFIG_64BIT as some x86 drivers use non-atomicwriteq() */
> +#if defined(writeq) && defined(readq)
> +#ifndef setbits_le64
> +#define setbits_le64(addr, set) __setbits(readq, writeq, addr, set)
> +#endif
> +#ifndef setbits_le64_relaxed
> +#define setbits_le64_relaxed(addr, set) __setbits(readq_relaxed, writeq_relaxed, \
> +					       addr, set)
> +#endif
> +
> +#ifndef clrbits_le64
> +#define clrbits_le64(addr, mask) __clrbits(readq, writeq, addr, mask)
> +#endif
> +#ifndef clrbits_le64_relaxed
> +#define clrbits_le64_relaxed(addr, mask) __clrbits(readq_relaxed, writeq_relaxed, \
> +						addr, mask)
> +#endif
> +
> +#ifndef clrsetbits_le64
> +#define clrsetbits_le64(addr, mask, set) __clrsetbits(readq, writeq, addr, mask, set)
> +#endif
> +#ifndef clrsetbits_le64_relaxed
> +#define clrsetbits_le64_relaxed(addr, mask, set) __clrsetbits(readq_relaxed, \
> +							   writeq_relaxed, \
> +							   addr, mask, set)
> +#endif
> +
> +#ifndef setclrbits_le64
> +#define setclrbits_le64(addr, mask, set) __setclrbits(readq, writeq, addr, mask, set)
> +#endif
> +#ifndef setclrbits_le64_relaxed
> +#define setclrbits_le64_relaxed(addr, mask, set) __setclrbits(readq_relaxed, \
> +							   writeq_relaxed, \
> +							   addr, mask, set)
> +#endif
> +
> +#endif /* writeq/readq */
> +
> +#endif /* __LINUX_SETBITS_H */