[PATCH 6.8 050/172] s390/ism: fix receive message buffer allocation

Greg Kroah-Hartman
2024-04-15T14:26:15Z

From: Gerd Bayer <gbayer@linux.ibm.com>

[ Upstream commit 58effa3476536215530c9ec4910ffc981613b413 ]

Since [1], dma_alloc_coherent() does not accept requests for GFP_COMP
anymore, even on archs that may be able to fulfill this. Functionality that
relied on the receive buffer being a compound page broke at that point:
The SMC-D protocol, that utilizes the ism device driver, passes receive
buffers to the splice processor in a struct splice_pipe_desc with a
single entry list of struct pages. As the buffer is no longer a compound
page, the splice processor now rejects requests to handle more than a
page worth of data.

Replace dma_alloc_coherent() and allocate a buffer with folio_alloc and
create a DMA map for it with dma_map_page(). Since only receive buffers
on ISM devices use DMA, qualify the mapping as FROM_DEVICE.
Since ISM devices are available on arch s390, only and on that arch all
DMA is coherent, there is no need to introduce and export some kind of
dma_sync_to_cpu() method to be called by the SMC-D protocol layer.

Analogously, replace dma_free_coherent by a two step dma_unmap_page,
then folio_put to free the receive buffer.

[1] https://lore.kernel.org/all/20221113163535.884299-1-hch@lst.de/

Fixes: c08004eede4b ("s390/ism: don't pass bogus GFP_ flags to dma_alloc_coherent")
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/s390/net/ism_drv.c | 38 +++++++++++++++++++++++++++++---------
1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c
index 2c8e964425dc3..affb05521e146 100644
--- a/drivers/s390/net/ism_drv.c
+++ b/drivers/s390/net/ism_drv.c
@@ -14,6 +14,8 @@
#include <linux/err.h>
#include <linux/ctype.h>
#include <linux/processor.h>
+#include <linux/dma-mapping.h>
+#include <linux/mm.h>

#include "ism.h"

@@ -292,13 +294,15 @@ static int ism_read_local_gid(struct ism_dev *ism)
static void ism_free_dmb(struct ism_dev *ism, struct ism_dmb *dmb)
{
clear_bit(dmb->sba_idx, ism->sba_bitmap);
- dma_free_coherent(&ism->pdev->dev, dmb->dmb_len,
- dmb->cpu_addr, dmb->dma_addr);
+ dma_unmap_page(&ism->pdev->dev, dmb->dma_addr, dmb->dmb_len,
+ DMA_FROM_DEVICE);
+ folio_put(virt_to_folio(dmb->cpu_addr));
}

static int ism_alloc_dmb(struct ism_dev *ism, struct ism_dmb *dmb)
{
unsigned long bit;
+ int rc;

if (PAGE_ALIGN(dmb->dmb_len) > dma_get_max_seg_size(&ism->pdev->dev))
return -EINVAL;
@@ -315,14 +319,30 @@ static int ism_alloc_dmb(struct ism_dev *ism, struct ism_dmb *dmb)
test_and_set_bit(dmb->sba_idx, ism->sba_bitmap))
return -EINVAL;

- dmb->cpu_addr = dma_alloc_coherent(&ism->pdev->dev, dmb->dmb_len,
- &dmb->dma_addr,
- GFP_KERNEL | __GFP_NOWARN |
- __GFP_NOMEMALLOC | __GFP_NORETRY);
- if (!dmb->cpu_addr)
- clear_bit(dmb->sba_idx, ism->sba_bitmap);
+ dmb->cpu_addr =
+ folio_address(folio_alloc(GFP_KERNEL | __GFP_NOWARN |
+ __GFP_NOMEMALLOC | __GFP_NORETRY,
+ get_order(dmb->dmb_len)));

- return dmb->cpu_addr ? 0 : -ENOMEM;
+ if (!dmb->cpu_addr) {
+ rc = -ENOMEM;
+ goto out_bit;
+ }
+ dmb->dma_addr = dma_map_page(&ism->pdev->dev,
+ virt_to_page(dmb->cpu_addr), 0,
+ dmb->dmb_len, DMA_FROM_DEVICE);
+ if (dma_mapping_error(&ism->pdev->dev, dmb->dma_addr)) {
+ rc = -ENOMEM;
+ goto out_free;
+ }
+
+ return 0;
+
+out_free:
+ kfree(dmb->cpu_addr);
+out_bit:
+ clear_bit(dmb->sba_idx, ism->sba_bitmap);
+ return rc;
}

int ism_register_dmb(struct ism_dev *ism, struct ism_dmb *dmb,
--
2.43.0