From: Christoph Hellwig <hch@lst.de>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Huacai Chen <chenhc@lemote.com>, Christoph Hellwig <hch@lst.de>,
Robin Murphy <robin.murphy@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Fuxin Zhang <zhangfx@lemote.com>,
linux-kernel@vger.kernel.org, Ralf Baechle <ralf@linux-mips.org>,
James Hogan <james.hogan@imgtec.com>,
linux-mips@linux-mips.org,
"James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
linux-scsi@vger.kernel.org, Tejun Heo <tj@kernel.org>,
linux-ide@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH V8 4/5] libsas: Align SMP req/resp to dma_get_cache_alignment()
Date: Thu, 19 Oct 2017 17:12:14 +0200 [thread overview]
Message-ID: <20171019151214.GD24204@lst.de> (raw)
In-Reply-To: <286bf838-4d2f-a25f-baf9-ef3ac9b37d93@samsung.com>
On Tue, Oct 17, 2017 at 01:55:43PM +0200, Marek Szyprowski wrote:
> If I remember correctly, kernel guarantees that each kmalloced buffer is
> always at least aligned to the CPU cache line, so CPU cache can be
> invalidated on the allocated buffer without corrupting anything else.
Yes, from slab.h:
/*
* Some archs want to perform DMA into kmalloc caches and need a guaranteed
* alignment larger than the alignment of a 64-bit integer.
* Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
*/
#if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
#define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
#define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
#define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
#else
#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
#endif
Mips sets this for a few subarchitectures, but it seems like you need
to set it for yours as well.
next prev parent reply other threads:[~2017-10-19 15:12 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-17 8:05 [PATCH V8 1/5] dma-mapping: Rework dma_get_cache_alignment() Huacai Chen
2017-10-17 8:05 ` [PATCH V8 2/5] MIPS: Implement dma_map_ops::get_cache_alignment() Huacai Chen
2017-10-17 8:05 ` [PATCH V8 3/5] scsi: Align block queue to dma_get_cache_alignment() Huacai Chen
2017-10-19 15:10 ` Christoph Hellwig
2017-10-17 8:05 ` [PATCH V8 4/5] libsas: Align SMP req/resp " Huacai Chen
2017-10-17 11:55 ` Marek Szyprowski
2017-10-18 1:12 ` [PATCH V8 4/5] libsas: Align SMP req/resp todma_get_cache_alignment() 陈华才
2017-10-19 15:12 ` Christoph Hellwig [this message]
2017-10-20 0:04 ` [PATCH V8 4/5] libsas: Align SMP req/resp to dma_get_cache_alignment() kbuild test robot
2017-10-17 8:05 ` [PATCH V8 5/5] libata: Align DMA buffer " Huacai Chen
2017-10-17 9:43 ` Sergei Shtylyov
2017-10-18 1:06 ` [PATCH V8 5/5] libata: Align DMA buffer todma_get_cache_alignment() 陈华才
2017-10-18 19:54 ` [PATCH V8 5/5] libata: Align DMA buffer to dma_get_cache_alignment() Alan Cox
2017-10-18 13:03 ` Tejun Heo
2017-10-19 7:52 ` Matt Redfearn
2017-10-20 4:25 ` [PATCH V8 5/5] libata: Align DMA buffer todma_get_cache_alignment() 陈华才
2017-10-18 17:23 ` [PATCH V8 1/5] dma-mapping: Rework dma_get_cache_alignment() Mark Greer
2017-10-19 15:09 ` Christoph Hellwig
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