From: Russell King <rmk+lkml@arm.linux.org.uk>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@osdl.org, akpm@osdl.org, davem@davemloft.com,
matthew@wil.cx, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org
Subject: Re: [PATCH 1/2] WorkStruct: Add assign_bits() to give an atomic-bitops safe assignment
Date: Tue, 12 Dec 2006 22:54:44 +0000 [thread overview]
Message-ID: <20061212225443.GA25902@flint.arm.linux.org.uk> (raw)
In-Reply-To: <20061212201112.29817.22041.stgit@warthog.cambridge.redhat.com>
On Tue, Dec 12, 2006 at 08:11:12PM +0000, David Howells wrote:
> diff --git a/include/asm-arm/bitops.h b/include/asm-arm/bitops.h
> index b41831b..5932134 100644
> --- a/include/asm-arm/bitops.h
> +++ b/include/asm-arm/bitops.h
> @@ -117,6 +117,32 @@ ____atomic_test_and_change_bit(unsigned
> return res & mask;
> }
>
> +#if __LINUX_ARM_ARCH__ >= 6 && defined(CONFIG_CPU_32v6K)
> +static inline void assign_bits(unsigned long v, unsigned long *addr)
> +{
> + unsigned long tmp;
> +
> + __asm__ __volatile__("@ atomic_set\n"
> +"1: ldrex %0, [%1]\n"
> +" strex %0, %2, [%1]\n"
> +" teq %0, #0\n"
> +" bne 1b"
> + : "=&r" (tmp)
> + : "r" (addr), "r" (v)
> + : "cc");
> +}
This seems to be a very silly question (and I'm bound to be utterly
wrong as proven in my last round) but why are we implementing a new
set of atomic primitives which effectively do the same thing as our
existing set?
Why can't we just use atomic_t for this?
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
next prev parent reply other threads:[~2006-12-12 22:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-12 20:11 [PATCH 1/2] WorkStruct: Add assign_bits() to give an atomic-bitops safe assignment David Howells
2006-12-12 20:11 ` [PATCH 2/2] WorkStruct: Use bitops-safe direct assignment David Howells
2006-12-12 22:54 ` Russell King [this message]
2006-12-12 23:03 ` [PATCH 1/2] WorkStruct: Add assign_bits() to give an atomic-bitops safe assignment Paul Mackerras
2006-12-12 23:17 ` David Howells
2006-12-13 1:36 ` Linus Torvalds
2006-12-13 2:07 ` Nick Piggin
2006-12-13 2:30 ` Linus Torvalds
2006-12-15 22:45 ` Linus Torvalds
2006-12-18 8:56 ` David Woodhouse
2006-12-18 9:05 ` Evgeniy Polyakov
2006-12-18 9:10 ` David Miller
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