4 messages, 2 authors, 2011-02-20 · open the first message on its own page
From: Steve Muckle <hidden>
Date: 2011-02-03 02:05:46
Hello, Looking at kernel/mutex.c and arch/arm/include/asm/mutex.h, it appears there aren't any memory barriers in the fast path of mutexes. I see this was discussed here a long time back: http://patchwork.kernel.org/patch/25856/ How was this resolved? thanks, Steve -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
From: Russell King - ARM Linux <hidden>
Date: 2011-02-03 11:08:37
On Wed, Feb 02, 2011 at 06:05:46PM -0800, Steve Muckle wrote:
Hello, Looking at kernel/mutex.c and arch/arm/include/asm/mutex.h, it appears there aren't any memory barriers in the fast path of mutexes. I see this was discussed here a long time back: http://patchwork.kernel.org/patch/25856/ How was this resolved?
bac4e96 ([ARM] barriers: improve xchg, bitops and atomic SMP barriers)
From: Steve Muckle <hidden>
Date: 2011-02-03 16:56:15
On 02/03/11 03:08, Russell King - ARM Linux wrote:
On Wed, Feb 02, 2011 at 06:05:46PM -0800, Steve Muckle wrote:quoted
Looking at kernel/mutex.c and arch/arm/include/asm/mutex.h, it appears there aren't any memory barriers in the fast path of mutexes. I see this was discussed here a long time back: http://patchwork.kernel.org/patch/25856/ How was this resolved?bac4e96 ([ARM] barriers: improve xchg, bitops and atomic SMP barriers)
The fast path of mutexes on ARM >= v6 doesn't seem to use these operations - it's just ldrex/strex. Looking at the v7 ARM ARM it seems barriers are still required with ldrex/strex. thanks, Steve -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
From: Russell King - ARM Linux <hidden>
Date: 2011-02-20 13:14:02
On Thu, Feb 03, 2011 at 08:56:15AM -0800, Steve Muckle wrote:
On 02/03/11 03:08, Russell King - ARM Linux wrote:quoted
On Wed, Feb 02, 2011 at 06:05:46PM -0800, Steve Muckle wrote:quoted
Looking at kernel/mutex.c and arch/arm/include/asm/mutex.h, it appears there aren't any memory barriers in the fast path of mutexes. I see this was discussed here a long time back: http://patchwork.kernel.org/patch/25856/ How was this resolved?bac4e96 ([ARM] barriers: improve xchg, bitops and atomic SMP barriers)The fast path of mutexes on ARM >= v6 doesn't seem to use these operations - it's just ldrex/strex. Looking at the v7 ARM ARM it seems barriers are still required with ldrex/strex.
Patch welcome.