V4L/DVB (5592): DMA: Correctly free resources on error, sync PCI streamed data

I added saa7146_vmalloc_destroy_pgtable() which frees the resources
allocated by saa7146_vmalloc_build_pgtable() and updated the callers in
budget-core.c and av7110.c. I have also been through the updated
functions and updated the error paths to ensure they free all allocated
resources on error.
I also realised that there are other callers to saa7146_pgtable_free()
which did not have any sg DMA mapped so it seems wrong to add the
pci_unmap_sg() into that function. Instead I created
saa7146_vmalloc_destroy_pgtable() to do this.
Also included in this patch are the previous fixes for pci_unmap_sg()
and syncing the PCI streamed data to work with a SWIOTLB and match the
requirements documented in DMA-API.txt.

Signed-off-by: Jon Burgess <jburgess777@googlemail.com>
Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 35 insertions, 19 deletions

diff --git a/drivers/media/common/saa7146_core.c b/drivers/media/common/saa7146_core.c
index 86cbdbcf9d..ef3e54cd94 100644
--- a/drivers/media/common/saa7146_core.c
+++ b/drivers/media/common/saa7146_core.c
@@ -136,28 +136,45 @@ char *saa7146_vmalloc_build_pgtable(struct pci_dev *pci, long length, struct saa
         char *mem = vmalloc_32(length);
         int slen = 0;
 
-        if (NULL == mem) {
-                return NULL;
-        }
+        if (NULL == mem)
+                goto err_null;
 
-        if (!(pt->slist = vmalloc_to_sg(mem, pages))) {
-                vfree(mem);
-                return NULL;
-        }
+        if (!(pt->slist = vmalloc_to_sg(mem, pages)))
+                goto err_free_mem;
 
-        if (saa7146_pgtable_alloc(pci, pt)) {
-                kfree(pt->slist);
-                pt->slist = NULL;
-                vfree(mem);
-                return NULL;
-        }
+        if (saa7146_pgtable_alloc(pci, pt))
+                goto err_free_slist;
 
-        slen = pci_map_sg(pci,pt->slist,pages,PCI_DMA_FROMDEVICE);
-        if (0 != saa7146_pgtable_build_single(pci, pt, pt->slist, slen)) {
-                return NULL;
-        }
+        pt->nents = pages;
+        slen = pci_map_sg(pci,pt->slist,pt->nents,PCI_DMA_FROMDEVICE);
+        if (0 == slen)
+                goto err_free_pgtable;
+
+        if (0 != saa7146_pgtable_build_single(pci, pt, pt->slist, slen))
+                goto err_unmap_sg;
 
         return mem;
+
+err_unmap_sg:
+        pci_unmap_sg(pci, pt->slist, pt->nents, PCI_DMA_FROMDEVICE);
+err_free_pgtable:
+        saa7146_pgtable_free(pci, pt);
+err_free_slist:
+        kfree(pt->slist);
+        pt->slist = NULL;
+err_free_mem:
+        vfree(mem);
+err_null:
+        return NULL;
+}
+
+void saa7146_vfree_destroy_pgtable(struct pci_dev *pci, char *mem, struct saa7146_pgtable *pt)
+{
+        pci_unmap_sg(pci, pt->slist, pt->nents, PCI_DMA_FROMDEVICE);
+        saa7146_pgtable_free(pci, pt);
+        kfree(pt->slist);
+        pt->slist = NULL;
+        vfree(mem);
 }
 
 void saa7146_pgtable_free(struct pci_dev *pci, struct saa7146_pgtable *pt)
@@ -166,8 +183,6 @@ void saa7146_pgtable_free(struct pci_dev *pci, struct saa7146_pgtable *pt)
                 return;
         pci_free_consistent(pci, pt->size, pt->cpu, pt->dma);
         pt->cpu = NULL;
-        kfree(pt->slist);
-        pt->slist = NULL;
 }
 
 int saa7146_pgtable_alloc(struct pci_dev *pci, struct saa7146_pgtable *pt)
@@ -528,6 +543,7 @@ EXPORT_SYMBOL_GPL(saa7146_pgtable_alloc);
 EXPORT_SYMBOL_GPL(saa7146_pgtable_free);
 EXPORT_SYMBOL_GPL(saa7146_pgtable_build_single);
 EXPORT_SYMBOL_GPL(saa7146_vmalloc_build_pgtable);
+EXPORT_SYMBOL_GPL(saa7146_vfree_destroy_pgtable);
 EXPORT_SYMBOL_GPL(saa7146_wait_for_debi_done);
 
 EXPORT_SYMBOL_GPL(saa7146_setgpio);