From: Stephen Warren <swarren@xxxxxxxxxx>
This patch solves a crash at the time of mlx4 driver unload or system
shutdown. The crash occurs because dma_alloc_coherent() returns one
value in mlx4_alloc_icm_coherent(), but a different value is passed to
dma_free_coherent() in mlx4_free_icm_coherent(). In turn this is because
when allocated, that pointer is passed to sg_set_buf() to record it,
then when freed it is re-calculated by calling
lowmem_page_address(sg_page()) which returns a different value. Solve
this by recording the value that dma_alloc_coherent() returns, and
passing this to dma_free_coherent().
This change is equivalent to commit 378efe798ecf ("RDMA/hns: Get rid of
page operation after dma_alloc_coherent"). That change was described as:
> In general, dma_alloc_coherent() returns a CPU virtual address and
> a DMA address, and we have no guarantee that the underlying memory
> even has an associated struct page at all.
>
> This patch gets rid of the page operation after dma_alloc_coherent,
> and records the VA returned form dma_alloc_coherent in the struct
> of hem in hns RoCE driver.
Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx>
---
v2:
- Rework mlx4_table_find() to explicitly calculate the returned address
differently depending on wheter the table was allocated using
dma_alloc_coherent() or alloc_pages(), which in turn allows the
changes to mlx4_alloc_icm_pages() to be dropped.
- Drop changes to mlx4_alloc/free_icm_pages. This path uses
pci_map_sg() which can re-write the sg list which in turn would cause
chunk->mem[] (the sg list) and chunk->buf[] to become inconsistent.
- Enhance commit description.
Note: I've tested this patch in a downstream 4.14 based kernel (using
ibping, ib_read_bw, and ib_write_bw), but can't test it in mainline
since my system isn't supported there yet. I have compile-tested it in
mainline at least, for ARM64.
---
drivers/net/ethernet/mellanox/mlx4/icm.c | 30 +++++++++++++++---------
drivers/net/ethernet/mellanox/mlx4/icm.h | 1 +
2 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/icm.c b/drivers/net/ethernet/mellanox/mlx4/icm.c
index 4b4351141b94..901110c7530a 100644
--- a/drivers/net/ethernet/mellanox/mlx4/icm.c
+++ b/drivers/net/ethernet/mellanox/mlx4/icm.c
@@ -72,7 +72,7 @@ static void mlx4_free_icm_coherent(struct mlx4_dev *dev, struct mlx4_icm_chunk *
for (i = 0; i < chunk->npages; ++i)
dma_free_coherent(&dev->persist->pdev->dev,
chunk->mem[i].length,
- lowmem_page_address(sg_page(&chunk->mem[i])),
+ chunk->buf[i],
sg_dma_address(&chunk->mem[i]));
}
@@ -112,20 +112,20 @@ static int mlx4_alloc_icm_pages(struct scatterlist *mem, int order,
}
static int mlx4_alloc_icm_coherent(struct device *dev, struct scatterlist *mem,
- int order, gfp_t gfp_mask)
+ void **buf, int order, gfp_t gfp_mask)
{
- void *buf = dma_alloc_coherent(dev, PAGE_SIZE << order,
- &sg_dma_address(mem), gfp_mask);
- if (!buf)
+ *buf = dma_alloc_coherent(dev, PAGE_SIZE << order,
+ &sg_dma_address(mem), gfp_mask);
+ if (!*buf)
return -ENOMEM;
- if (offset_in_page(buf)) {
+ if (offset_in_page(*buf)) {
dma_free_coherent(dev, PAGE_SIZE << order,
- buf, sg_dma_address(mem));
+ *buf, sg_dma_address(mem));
return -ENOMEM;
}
- sg_set_buf(mem, buf, PAGE_SIZE << order);
+ mem->length = PAGE_SIZE << order;
sg_dma_len(mem) = PAGE_SIZE << order;
return 0;
}
@@ -174,6 +174,7 @@ struct mlx4_icm *mlx4_alloc_icm(struct mlx4_dev *dev, int npages,
sg_init_table(chunk->mem, MLX4_ICM_CHUNK_LEN);
chunk->npages = 0;
chunk->nsg = 0;
+ memset(chunk->buf, 0, sizeof(chunk->buf));
list_add_tail(&chunk->list, &icm->chunk_list);
}
@@ -187,6 +188,7 @@ struct mlx4_icm *mlx4_alloc_icm(struct mlx4_dev *dev, int npages,
if (coherent)
ret = mlx4_alloc_icm_coherent(&dev->persist->pdev->dev,
&chunk->mem[chunk->npages],
+ &chunk->buf[chunk->npages],
cur_order, mask);
else
ret = mlx4_alloc_icm_pages(&chunk->mem[chunk->npages],
@@ -320,7 +322,8 @@ void *mlx4_table_find(struct mlx4_icm_table *table, u32 obj,
u64 idx;
struct mlx4_icm_chunk *chunk;
struct mlx4_icm *icm;
- struct page *page = NULL;
+ struct page *page;
+ void *addr = NULL;
if (!table->lowmem)
return NULL;
@@ -348,7 +351,12 @@ void *mlx4_table_find(struct mlx4_icm_table *table, u32 obj,
* been assigned to.
*/
if (chunk->mem[i].length > offset) {
- page = sg_page(&chunk->mem[i]);
+ if (table->coherent) {
+ addr = chunk->buf[i];
+ } else {
+ page = sg_page(&chunk->mem[i]);
+ addr = lowmem_page_address(page);
+ }
goto out;
}
offset -= chunk->mem[i].length;
@@ -357,7 +365,7 @@ void *mlx4_table_find(struct mlx4_icm_table *table, u32 obj,
out:
mutex_unlock(&table->mutex);
- return page ? lowmem_page_address(page) + offset : NULL;
+ return addr ? addr + offset : NULL;
}
int mlx4_table_get_range(struct mlx4_dev *dev, struct mlx4_icm_table *table,
diff --git a/drivers/net/ethernet/mellanox/mlx4/icm.h b/drivers/net/ethernet/mellanox/mlx4/icm.h
index c9169a490557..a565188dc391 100644
--- a/drivers/net/ethernet/mellanox/mlx4/icm.h
+++ b/drivers/net/ethernet/mellanox/mlx4/icm.h
@@ -52,6 +52,7 @@ struct mlx4_icm_chunk {
int npages;
int nsg;
struct scatterlist mem[MLX4_ICM_CHUNK_LEN];
+ void *buf[MLX4_ICM_CHUNK_LEN];
};
struct mlx4_icm {
--
2.19.2
