From 6de7e356faf54aa75de5b624bbce28a5b776dfa8 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 18 Jun 2009 10:19:12 +0200 Subject: [PATCH] lib/scatterlist: add a flags to signalize mapping direction sg_miter_start() is currently unaware of the direction of the copy process (to or from the scatter list). It is important to know the direction because the page has to be flushed in case the data written is seen on a different mapping in user land on cache incoherent architectures. Signed-off-by: Sebastian Andrzej Siewior Acked-by: FUJITA Tomonori Acked-by: Tejun Heo Signed-off-by: Pierre Ossman --- include/linux/scatterlist.h | 2 ++ lib/scatterlist.c | 16 ++++++++++++---- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index e599698..9aaf5bf 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -242,6 +242,8 @@ size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, */ #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ +#define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ +#define SG_MITER_FROM_SG (1 << 2) /* nop */ struct sg_mapping_iter { /* the following three fields can be accessed directly */ diff --git a/lib/scatterlist.c b/lib/scatterlist.c index a295e40..0d475d8 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -314,6 +314,7 @@ void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, miter->__sg = sgl; miter->__nents = nents; miter->__offset = 0; + WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); miter->__flags = flags; } EXPORT_SYMBOL(sg_miter_start); @@ -394,6 +395,9 @@ void sg_miter_stop(struct sg_mapping_iter *miter) if (miter->addr) { miter->__offset += miter->consumed; + if (miter->__flags & SG_MITER_TO_SG) + flush_kernel_dcache_page(miter->page); + if (miter->__flags & SG_MITER_ATOMIC) { WARN_ON(!irqs_disabled()); kunmap_atomic(miter->addr, KM_BIO_SRC_IRQ); @@ -426,8 +430,14 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, unsigned int offset = 0; struct sg_mapping_iter miter; unsigned long flags; + unsigned int sg_flags = SG_MITER_ATOMIC; + + if (to_buffer) + sg_flags |= SG_MITER_FROM_SG; + else + sg_flags |= SG_MITER_TO_SG; - sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC); + sg_miter_start(&miter, sgl, nents, sg_flags); local_irq_save(flags); @@ -438,10 +448,8 @@ static size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, if (to_buffer) memcpy(buf + offset, miter.addr, len); - else { + else memcpy(miter.addr, buf + offset, len); - flush_kernel_dcache_page(miter.page); - } offset += len; } -- 1.8.2.3