Re: snd_pcm_lib_preallocate_pages_for_all

[Takashi Iwai <tiwai@suse.de>]

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At Mon, 5 Jul 2004 13:57:22 +0300,
Bo Henriksen wrote:
> 
> 
> From my understanding you are saying that I can get my driver working
> with the current ALSA by removing the _MMAP_ flags. 
> 
> runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP|SNDRV_PCM_INFO_MMAP_VALID);
> 
> However, I do not have a pointer to the runtime or the substream at this
> stage. How do I change the HW permissions before I call
> snd_pcm_lib_preallocate_pages_for_all, where everything crashes, which
> is called in snd_mychip_new_pcm? I believe they are set only in the open
> callback in the example from the documentation.

Ah, of course, the crash in snd_pcm_lib_preallocate_pages_for_all has
nothing to do with mmap.  I overlooked the point of crash.

The attached patch should fix it.


Takashi

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Index: alsa-kernel/core/memalloc.c
===================================================================
RCS file: /suse/tiwai/cvs/alsa/alsa-kernel/core/memalloc.c,v
retrieving revision 1.34
diff -u -r1.34 memalloc.c
--- alsa-kernel/core/memalloc.c	2 Jul 2004 13:17:39 -0000	1.34
+++ alsa-kernel/core/memalloc.c	5 Jul 2004 11:06:31 -0000
@@ -160,24 +160,6 @@
 
 static long snd_allocated_pages; /* holding the number of allocated pages */
 
-static void mark_pages(void *res, int order)
-{
-	struct page *page = virt_to_page(res);
-	struct page *last_page = page + (1 << order);
-	while (page < last_page)
-		SetPageReserved(page++);
-	snd_allocated_pages += 1 << order;
-}
-
-static void unmark_pages(void *res, int order)
-{
-	struct page *page = virt_to_page(res);
-	struct page *last_page = page + (1 << order);
-	while (page < last_page)
-		ClearPageReserved(page++);
-	snd_allocated_pages -= 1 << order;
-}
-
 /**
  * snd_malloc_pages - allocate pages with the given size
  * @size: the size to allocate in bytes
@@ -190,15 +172,11 @@
 void *snd_malloc_pages(size_t size, unsigned int gfp_flags)
 {
 	int pg;
-	void *res;
 
 	snd_assert(size > 0, return NULL);
 	snd_assert(gfp_flags != 0, return NULL);
-	for (pg = 0; PAGE_SIZE * (1 << pg) < size; pg++);
-	if ((res = (void *) __get_free_pages(gfp_flags, pg)) != NULL) {
-		mark_pages(res, pg);
-	}
-	return res;
+	pg = get_order(size);
+	return (void *) __get_free_pages(gfp_flags, pg);
 }
 
 /**
@@ -243,8 +221,7 @@
 
 	if (ptr == NULL)
 		return;
-	for (pg = 0; PAGE_SIZE * (1 << pg) < size; pg++);
-	unmark_pages(ptr, pg);
+	pg = get_order(size);
 	free_pages((unsigned long) ptr, pg);
 }
 
@@ -254,10 +231,10 @@
  *
  */
 
+/* allocate the coherent DMA pages */
 static void *snd_malloc_dev_pages(struct device *dev, size_t size, dma_addr_t *dma)
 {
 	int pg;
-	void *res;
 	unsigned int gfp_flags;
 
 	snd_assert(size > 0, return NULL);
@@ -266,11 +243,7 @@
 	gfp_flags = GFP_KERNEL;
 	if (pg > 0)
 		gfp_flags |= __GFP_NOWARN;
-	res = dma_alloc_coherent(dev, PAGE_SIZE << pg, dma, gfp_flags);
-	if (res != NULL)
-		mark_pages(res, pg);
-
-	return res;
+	return dma_alloc_coherent(dev, PAGE_SIZE << pg, dma, gfp_flags);
 }
 
 static void *snd_malloc_dev_pages_fallback(struct device *dev, size_t size,
@@ -289,6 +262,7 @@
 	return NULL;
 }
 
+/* free the coherent DMA pages */
 static void snd_free_dev_pages(struct device *dev, size_t size, void *ptr,
 			       dma_addr_t dma)
 {
@@ -297,7 +271,6 @@
 	if (ptr == NULL)
 		return;
 	pg = get_order(size);
-	unmark_pages(ptr, pg);
 	dma_free_coherent(dev, PAGE_SIZE << pg, ptr, dma);
 }
 
@@ -308,16 +281,11 @@
 {
 	struct sbus_dev *sdev = (struct sbus_dev *)dev;
 	int pg;
-	void *res;
 
 	snd_assert(size > 0, return NULL);
 	snd_assert(dma_addr != NULL, return NULL);
-	for (pg = 0; PAGE_SIZE * (1 << pg) < size; pg++);
-	res = sbus_alloc_consistent(sdev, PAGE_SIZE * (1 << pg), dma_addr);
-	if (res != NULL) {
-		mark_pages(res, pg);
-	}
-	return res;
+	pg = get_order(size);
+	return sbus_alloc_consistent(sdev, PAGE_SIZE * (1 << pg), dma_addr);
 }
 
 static void *snd_malloc_sbus_pages_fallback(struct device *dev, size_t size,
@@ -344,8 +312,7 @@
 
 	if (ptr == NULL)
 		return;
-	for (pg = 0; PAGE_SIZE * (1 << pg) < size; pg++);
-	unmark_pages(ptr, pg);
+	pg = get_order(size);
 	sbus_free_consistent(sdev, PAGE_SIZE * (1 << pg), ptr, dma_addr);
 }
 
@@ -474,7 +441,7 @@
 /**
  * snd_dma_free_pages - release the allocated buffer
  * @dev: the buffer device info
- * @dmbab: the buffer allocation record to release
+ * @dmab: the buffer allocation record to release
  *
  * Releases the allocated buffer via snd_dma_alloc_pages().
  */