[PATCH] v4l2: change kmalloc to vmalloc for sglist allocation in videobuf_dma_map/unmap

[David . Cohen . david . cohen]

From: Cohen David.A (Nokia-D/Helsinki) <david.co...@nokia.com>

Change kmalloc()/kfree() to vmalloc()/vfree() for sglist allocation
during videobuf_dma_map() and videobuf_dma_unmap()

High resolution sensors might require too many contiguous pages
to be allocated for sglist by kmalloc() during videobuf_dma_map()
(i.e. 256Kib for 8MP sensor).
In such situations, kmalloc() could face some problem to find the
required free memory. vmalloc() is a safer solution instead, as the
allocated memory does not need to be contiguous.

Signed-off-by: David Cohen <david.co...@nokia.com>
---
 drivers/media/video/videobuf-dma-sg.c |   17 +++++++++--------
 1 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/media/video/videobuf-dma-sg.c 
b/drivers/media/video/videobuf-dma-sg.c
index da1790e..c9a5d7e 100644
--- a/drivers/media/video/videobuf-dma-sg.c
+++ b/drivers/media/video/videobuf-dma-sg.c
@@ -58,9 +58,10 @@ videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
        struct page *pg;
        int i;
 
-       sglist = kcalloc(nr_pages, sizeof(struct scatterlist), GFP_KERNEL);
+       sglist = vmalloc(nr_pages * sizeof(*sglist));
        if (NULL == sglist)
                return NULL;
+       memset(sglist, 0, nr_pages * sizeof(*sglist));
        sg_init_table(sglist, nr_pages);
        for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
                pg = vmalloc_to_page(virt);
@@ -72,7 +73,7 @@ videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
        return sglist;
 
  err:
-       kfree(sglist);
+       vfree(sglist);
        return NULL;
 }
 
@@ -84,7 +85,7 @@ videobuf_pages_to_sg(struct page **pages, int nr_pages, int 
offset)
 
        if (NULL == pages[0])
                return NULL;
-       sglist = kmalloc(nr_pages * sizeof(*sglist), GFP_KERNEL);
+       sglist = vmalloc(nr_pages * sizeof(*sglist));
        if (NULL == sglist)
                return NULL;
        sg_init_table(sglist, nr_pages);
@@ -104,12 +105,12 @@ videobuf_pages_to_sg(struct page **pages, int nr_pages, 
int offset)
 
  nopage:
        dprintk(2,"sgl: oops - no page\n");
-       kfree(sglist);
+       vfree(sglist);
        return NULL;
 
  highmem:
        dprintk(2,"sgl: oops - highmem page\n");
-       kfree(sglist);
+       vfree(sglist);
        return NULL;
 }
 
@@ -230,7 +231,7 @@ int videobuf_dma_map(struct videobuf_queue* q, struct 
videobuf_dmabuf *dma)
                                                (dma->vmalloc,dma->nr_pages);
        }
        if (dma->bus_addr) {
-               dma->sglist = kmalloc(sizeof(struct scatterlist), GFP_KERNEL);
+               dma->sglist = vmalloc(sizeof(*dma->sglist));
                if (NULL != dma->sglist) {
                        dma->sglen  = 1;
                        sg_dma_address(&dma->sglist[0]) = dma->bus_addr & 
PAGE_MASK;
@@ -248,7 +249,7 @@ int videobuf_dma_map(struct videobuf_queue* q, struct 
videobuf_dmabuf *dma)
                if (0 == dma->sglen) {
                        printk(KERN_WARNING
                               "%s: videobuf_map_sg failed\n",__func__);
-                       kfree(dma->sglist);
+                       vfree(dma->sglist);
                        dma->sglist = NULL;
                        dma->sglen = 0;
                        return -EIO;
@@ -274,7 +275,7 @@ int videobuf_dma_unmap(struct videobuf_queue* q,struct 
videobuf_dmabuf *dma)
 
        dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 
-       kfree(dma->sglist);
+       vfree(dma->sglist);
        dma->sglist = NULL;
        dma->sglen = 0;
        return 0;
-- 
1.6.1

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