From: Christoph Hellwig <hch@lst.de>
Date: Wed, 13 Nov 2019 08:32:13 +0100
Subject: dma-mapping: remove the DMA_ATTR_WRITE_BARRIER flag
Git-commit: 7283fff8b524b2f27438429aca458b232f5c5c8a
Patch-mainline: v5.5-rc1
References: bsc#1175713
This flag is not implemented by any backend and only set by the ib_umem
module in a single instance.
Link: https://lore.kernel.org/r/20191113073214.9514-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
Documentation/DMA-attributes.txt | 18 ------------------
drivers/infiniband/core/umem.c | 9 ++-------
include/linux/dma-mapping.h | 5 +----
3 files changed, 3 insertions(+), 29 deletions(-)
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt
index 8f8d97f65d73..29dcbe8826e8 100644
--- a/Documentation/DMA-attributes.txt
+++ b/Documentation/DMA-attributes.txt
@@ -5,24 +5,6 @@ DMA attributes
This document describes the semantics of the DMA attributes that are
defined in linux/dma-mapping.h.
-DMA_ATTR_WRITE_BARRIER
-----------------------
-
-DMA_ATTR_WRITE_BARRIER is a (write) barrier attribute for DMA. DMA
-to a memory region with the DMA_ATTR_WRITE_BARRIER attribute forces
-all pending DMA writes to complete, and thus provides a mechanism to
-strictly order DMA from a device across all intervening busses and
-bridges. This barrier is not specific to a particular type of
-interconnect, it applies to the system as a whole, and so its
-implementation must account for the idiosyncrasies of the system all
-the way from the DMA device to memory.
-
-As an example of a situation where DMA_ATTR_WRITE_BARRIER would be
-useful, suppose that a device does a DMA write to indicate that data is
-ready and available in memory. The DMA of the "completion indication"
-could race with data DMA. Mapping the memory used for completion
-indications with DMA_ATTR_WRITE_BARRIER would prevent the race.
-
DMA_ATTR_WEAK_ORDERING
----------------------
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 24244a2f68cc..66148739b00f 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -199,7 +199,6 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
struct mm_struct *mm;
unsigned long npages;
int ret;
- unsigned long dma_attrs = 0;
struct scatterlist *sg;
unsigned int gup_flags = FOLL_WRITE;
@@ -211,9 +210,6 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
if (!context)
return ERR_PTR(-EIO);
- if (dmasync)
- dma_attrs |= DMA_ATTR_WRITE_BARRIER;
-
/*
* If the combination of the addr and size requested for this memory
* region causes an integer overflow, return error.
@@ -294,11 +290,10 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
sg_mark_end(sg);
- umem->nmap = ib_dma_map_sg_attrs(context->device,
+ umem->nmap = ib_dma_map_sg(context->device,
umem->sg_head.sgl,
umem->sg_nents,
- DMA_BIDIRECTIONAL,
- dma_attrs);
+ DMA_BIDIRECTIONAL);
if (!umem->nmap) {
ret = -ENOMEM;
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 4a1c4fca475a..8023071d6903 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -15,11 +15,8 @@
/**
* List of possible attributes associated with a DMA mapping. The semantics
* of each attribute should be defined in Documentation/DMA-attributes.txt.
- *
- * DMA_ATTR_WRITE_BARRIER: DMA to a memory region with this attribute
- * forces all pending DMA writes to complete.
*/
-#define DMA_ATTR_WRITE_BARRIER (1UL << 0)
+
/*
* DMA_ATTR_WEAK_ORDERING: Specifies that reads and writes to the mapping
* may be weakly ordered, that is that reads and writes may pass each other.