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 86cbdbcf9d7..ef3e54cd940 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);