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>

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);

drivers/media/dvb/ttpci/av7110.c

@@ -1246,6 +1246,9 @@ static void vpeirq(unsigned long data)
 	if (!budget->feeding1 || (newdma == olddma))
 		return;
 
+	/* Ensure streamed PCI data is synced to CPU */
+	pci_dma_sync_sg_for_cpu(budget->dev->pci, budget->pt.slist, budget->pt.nents, PCI_DMA_FROMDEVICE);
+
 #if 0
 	/* track rps1 activity */
 	printk("vpeirq: %02x Event Counter 1 0x%04x\n",
@@ -2679,8 +2682,8 @@ err_iobuf_vfree_6:
 err_pci_free_5:
 	pci_free_consistent(pdev, 8192, av7110->debi_virt, av7110->debi_bus);
 err_saa71466_vfree_4:
-	if (!av7110->grabbing)
-		saa7146_pgtable_free(pdev, &av7110->pt);
+	if (av7110->grabbing)
+		saa7146_vfree_destroy_pgtable(pdev, av7110->grabbing, &av7110->pt);
 err_i2c_del_3:
 	i2c_del_adapter(&av7110->i2c_adap);
 err_dvb_unregister_adapter_2:
@@ -2710,7 +2713,7 @@ static int __devexit av7110_detach(struct saa7146_dev* saa)
 		SAA7146_ISR_CLEAR(saa, MASK_10);
 		msleep(50);
 		tasklet_kill(&av7110->vpe_tasklet);
-		saa7146_pgtable_free(saa->pci, &av7110->pt);
+		saa7146_vfree_destroy_pgtable(saa->pci, av7110->grabbing, &av7110->pt);
 	}
 	av7110_exit_v4l(av7110);
 

drivers/media/dvb/ttpci/budget-core.c

@@ -195,6 +195,9 @@ static void vpeirq(unsigned long data)
 	u32 newdma = saa7146_read(budget->dev, PCI_VDP3);
 	u32 count;
 
+	/* Ensure streamed PCI data is synced to CPU */
+	pci_dma_sync_sg_for_cpu(budget->dev->pci, budget->pt.slist, budget->pt.nents, PCI_DMA_FROMDEVICE);
+
 	/* nearest lower position divisible by 188 */
 	newdma -= newdma % 188;
 
@@ -504,16 +507,16 @@ int ttpci_budget_init(struct budget *budget, struct saa7146_dev *dev,
 	strcpy(budget->i2c_adap.name, budget->card->name);
 
 	if (i2c_add_adapter(&budget->i2c_adap) < 0) {
-		dvb_unregister_adapter(&budget->dvb_adapter);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto err_dvb_unregister;
 	}
 
 	ttpci_eeprom_parse_mac(&budget->i2c_adap, budget->dvb_adapter.proposed_mac);
 
-	if (NULL ==
-	    (budget->grabbing = saa7146_vmalloc_build_pgtable(dev->pci, budget->buffer_size, &budget->pt))) {
+	budget->grabbing = saa7146_vmalloc_build_pgtable(dev->pci, budget->buffer_size, &budget->pt);
+	if (NULL == budget->grabbing) {
 		ret = -ENOMEM;
-		goto err;
+		goto err_del_i2c;
 	}
 
 	saa7146_write(dev, PCI_BT_V1, 0x001c0000);
@@ -526,14 +529,16 @@ int ttpci_budget_init(struct budget *budget, struct saa7146_dev *dev,
 	if (bi->type != BUDGET_FS_ACTIVY)
 		saa7146_setgpio(dev, 2, SAA7146_GPIO_OUTHI);
 
-	if (budget_register(budget) == 0) {
-		return 0;
-	}
-err:
-	i2c_del_adapter(&budget->i2c_adap);
+	if (budget_register(budget) == 0)
+		return 0; /* Everything OK */
+
+	/* An error occurred, cleanup resources */
+	saa7146_vfree_destroy_pgtable(dev->pci, budget->grabbing, &budget->pt);
 
-	vfree(budget->grabbing);
+err_del_i2c:
+	i2c_del_adapter(&budget->i2c_adap);
 
+err_dvb_unregister:
 	dvb_unregister_adapter(&budget->dvb_adapter);
 
 	return ret;
@@ -555,15 +560,13 @@ int ttpci_budget_deinit(struct budget *budget)
 
 	budget_unregister(budget);
 
-	i2c_del_adapter(&budget->i2c_adap);
-
-	dvb_unregister_adapter(&budget->dvb_adapter);
-
 	tasklet_kill(&budget->vpe_tasklet);
 
-	saa7146_pgtable_free(dev->pci, &budget->pt);
+	saa7146_vfree_destroy_pgtable(dev->pci, budget->grabbing, &budget->pt);
 
-	vfree(budget->grabbing);
+	i2c_del_adapter(&budget->i2c_adap);
+
+	dvb_unregister_adapter(&budget->dvb_adapter);
 
 	return 0;
 }

include/media/saa7146.h

@@ -58,6 +58,7 @@ struct saa7146_pgtable {
 	unsigned long	offset;
 	/* used for custom pagetables (used for example by budget dvb cards) */
 	struct scatterlist *slist;
+	int		nents;
 };
 
 struct saa7146_pci_extension_data {
@@ -157,6 +158,7 @@ int saa7146_pgtable_alloc(struct pci_dev *pci, struct saa7146_pgtable *pt);
 void saa7146_pgtable_free(struct pci_dev *pci, struct saa7146_pgtable *pt);
 int saa7146_pgtable_build_single(struct pci_dev *pci, struct saa7146_pgtable *pt, struct scatterlist *list, int length );
 char *saa7146_vmalloc_build_pgtable(struct pci_dev *pci, long length, struct saa7146_pgtable *pt);
+void saa7146_vfree_destroy_pgtable(struct pci_dev *pci, char *mem, struct saa7146_pgtable *pt);
 void saa7146_setgpio(struct saa7146_dev *dev, int port, u32 data);
 int saa7146_wait_for_debi_done(struct saa7146_dev *dev, int nobusyloop);