s390/ism: Properly fix receive message buffer allocation

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>

diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c
index 2c8e964425dc38ca80fa5009b17b4e9dc29bbf10..43778b088ffac54c4a8911f3e41e187f0ae3f364 100644 (file)
--- a/drivers/s390/net/ism_drv.c
+++ b/drivers/s390/net/ism_drv.c
@@ -292,13 +292,16 @@ 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)
 {
+       struct folio *folio;
        unsigned long bit;
+       int rc;
 
        if (PAGE_ALIGN(dmb->dmb_len) > dma_get_max_seg_size(&ism->pdev->dev))
                return -EINVAL;
@@ -315,14 +318,30 @@ 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);
+       folio = folio_alloc(GFP_KERNEL | __GFP_NOWARN | __GFP_NOMEMALLOC |
+                           __GFP_NORETRY, get_order(dmb->dmb_len));
 
-       return dmb->cpu_addr ? 0 : -ENOMEM;
+       if (!folio) {
+               rc = -ENOMEM;
+               goto out_bit;
+       }
+
+       dmb->cpu_addr = folio_address(folio);
+       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,