1 files changed, 56 insertions, 99 deletions

diff --git a/drivers/comedi/comedi_buf.c b/drivers/comedi/comedi_buf.c
index 393966c09740..002c0e76baff 100644
--- a/drivers/comedi/comedi_buf.c
+++ b/drivers/comedi/comedi_buf.c
@@ -27,14 +27,12 @@ static void comedi_buf_map_kref_release(struct kref *kref)
 
 	if (bm->page_list) {
 		if (bm->dma_dir != DMA_NONE) {
-			/*
-			 * DMA buffer was allocated as a single block.
-			 * Address is in page_list[0].
-			 */
-			buf = &bm->page_list[0];
-			dma_free_coherent(bm->dma_hw_dev,
-					  PAGE_SIZE * bm->n_pages,
-					  buf->virt_addr, buf->dma_addr);
+			for (i = 0; i < bm->n_pages; i++) {
+				buf = &bm->page_list[i];
+				dma_free_coherent(bm->dma_hw_dev, PAGE_SIZE,
+						  buf->virt_addr,
+						  buf->dma_addr);
+			}
 		} else {
 			for (i = 0; i < bm->n_pages; i++) {
 				buf = &bm->page_list[i];
@@ -56,13 +54,7 @@ static void __comedi_buf_free(struct comedi_device *dev,
 	struct comedi_buf_map *bm;
 	unsigned long flags;
 
-	if (async->prealloc_buf) {
-		if (s->async_dma_dir == DMA_NONE)
-			vunmap(async->prealloc_buf);
-		async->prealloc_buf = NULL;
-		async->prealloc_bufsz = 0;
-	}
-
+	async->prealloc_bufsz = 0;
 	spin_lock_irqsave(&s->spin_lock, flags);
 	bm = async->buf_map;
 	async->buf_map = NULL;
@@ -94,26 +86,14 @@ comedi_buf_map_alloc(struct comedi_device *dev, enum dma_data_direction dma_dir,
 		goto err;
 
 	if (bm->dma_dir != DMA_NONE) {
-		void *virt_addr;
-		dma_addr_t dma_addr;
-
-		/*
-		 * Currently, the DMA buffer needs to be allocated as a
-		 * single block so that it can be mmap()'ed.
-		 */
-		virt_addr = dma_alloc_coherent(bm->dma_hw_dev,
-					       PAGE_SIZE * n_pages, &dma_addr,
-					       GFP_KERNEL);
-		if (!virt_addr)
-			goto err;
-
 		for (i = 0; i < n_pages; i++) {
 			buf = &bm->page_list[i];
-			buf->virt_addr = virt_addr + (i << PAGE_SHIFT);
-			buf->dma_addr = dma_addr + (i << PAGE_SHIFT);
+			buf->virt_addr =
+			    dma_alloc_coherent(bm->dma_hw_dev, PAGE_SIZE,
+					       &buf->dma_addr, GFP_KERNEL);
+			if (!buf->virt_addr)
+				break;
 		}
-
-		bm->n_pages = i;
 	} else {
 		for (i = 0; i < n_pages; i++) {
 			buf = &bm->page_list[i];
@@ -123,11 +103,10 @@ comedi_buf_map_alloc(struct comedi_device *dev, enum dma_data_direction dma_dir,
 
 			SetPageReserved(virt_to_page(buf->virt_addr));
 		}
-
-		bm->n_pages = i;
-		if (i < n_pages)
-			goto err;
 	}
+	bm->n_pages = i;
+	if (i < n_pages)
+		goto err;
 
 	return bm;
 
@@ -141,11 +120,8 @@ static void __comedi_buf_alloc(struct comedi_device *dev,
 			       unsigned int n_pages)
 {
 	struct comedi_async *async = s->async;
-	struct page **pages = NULL;
 	struct comedi_buf_map *bm;
-	struct comedi_buf_page *buf;
 	unsigned long flags;
-	unsigned int i;
 
 	if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) {
 		dev_err(dev->class_dev,
@@ -160,30 +136,7 @@ static void __comedi_buf_alloc(struct comedi_device *dev,
 	spin_lock_irqsave(&s->spin_lock, flags);
 	async->buf_map = bm;
 	spin_unlock_irqrestore(&s->spin_lock, flags);
-
-	if (bm->dma_dir != DMA_NONE) {
-		/*
-		 * DMA buffer was allocated as a single block.
-		 * Address is in page_list[0].
-		 */
-		buf = &bm->page_list[0];
-		async->prealloc_buf = buf->virt_addr;
-	} else {
-		pages = vmalloc(sizeof(struct page *) * n_pages);
-		if (!pages)
-			return;
-
-		for (i = 0; i < n_pages; i++) {
-			buf = &bm->page_list[i];
-			pages[i] = virt_to_page(buf->virt_addr);
-		}
-
-		/* vmap the pages to prealloc_buf */
-		async->prealloc_buf = vmap(pages, n_pages, VM_MAP,
-					   COMEDI_PAGE_PROTECTION);
-
-		vfree(pages);
-	}
+	async->prealloc_bufsz = n_pages << PAGE_SHIFT;
 }
 
 void comedi_buf_map_get(struct comedi_buf_map *bm)
@@ -264,7 +217,7 @@ int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
 	new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK;
 
 	/* if no change is required, do nothing */
-	if (async->prealloc_buf && async->prealloc_bufsz == new_size)
+	if (async->prealloc_bufsz == new_size)
 		return 0;
 
 	/* deallocate old buffer */
@@ -275,14 +228,9 @@ int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
 		unsigned int n_pages = new_size >> PAGE_SHIFT;
 
 		__comedi_buf_alloc(dev, s, n_pages);
-
-		if (!async->prealloc_buf) {
-			/* allocation failed */
-			__comedi_buf_free(dev, s);
+		if (!async->prealloc_bufsz)
 			return -ENOMEM;
-		}
 	}
-	async->prealloc_bufsz = new_size;
 
 	return 0;
 }
@@ -365,6 +313,7 @@ static unsigned int comedi_buf_munge(struct comedi_subdevice *s,
 				     unsigned int num_bytes)
 {
 	struct comedi_async *async = s->async;
+	struct comedi_buf_page *buf_page_list = async->buf_map->page_list;
 	unsigned int count = 0;
 	const unsigned int num_sample_bytes = comedi_bytes_per_sample(s);
 
@@ -376,15 +325,16 @@ static unsigned int comedi_buf_munge(struct comedi_subdevice *s,
 	/* don't munge partial samples */
 	num_bytes -= num_bytes % num_sample_bytes;
 	while (count < num_bytes) {
-		int block_size = num_bytes - count;
-		unsigned int buf_end;
-
-		buf_end = async->prealloc_bufsz - async->munge_ptr;
-		if (block_size > buf_end)
-			block_size = buf_end;
+		/*
+		 * Do not munge beyond page boundary.
+		 * Note: prealloc_bufsz is a multiple of PAGE_SIZE.
+		 */
+		unsigned int page = async->munge_ptr >> PAGE_SHIFT;
+		unsigned int offset = offset_in_page(async->munge_ptr);
+		unsigned int block_size =
+			     min(num_bytes - count, PAGE_SIZE - offset);
 
-		s->munge(s->device, s,
-			 async->prealloc_buf + async->munge_ptr,
+		s->munge(s->device, s, buf_page_list[page].virt_addr + offset,
 			 block_size, async->munge_chan);
 
 		/*
@@ -397,7 +347,8 @@ static unsigned int comedi_buf_munge(struct comedi_subdevice *s,
 		async->munge_chan %= async->cmd.chanlist_len;
 		async->munge_count += block_size;
 		async->munge_ptr += block_size;
-		async->munge_ptr %= async->prealloc_bufsz;
+		if (async->munge_ptr == async->prealloc_bufsz)
+			async->munge_ptr = 0;
 		count += block_size;
 	}
 
@@ -558,46 +509,52 @@ static void comedi_buf_memcpy_to(struct comedi_subdevice *s,
 				 const void *data, unsigned int num_bytes)
 {
 	struct comedi_async *async = s->async;
+	struct comedi_buf_page *buf_page_list = async->buf_map->page_list;
 	unsigned int write_ptr = async->buf_write_ptr;
 
 	while (num_bytes) {
-		unsigned int block_size;
-
-		if (write_ptr + num_bytes > async->prealloc_bufsz)
-			block_size = async->prealloc_bufsz - write_ptr;
-		else
-			block_size = num_bytes;
+		/*
+		 * Do not copy beyond page boundary.
+		 * Note: prealloc_bufsz is a multiple of PAGE_SIZE.
+		 */
+		unsigned int page = write_ptr >> PAGE_SHIFT;
+		unsigned int offset = offset_in_page(write_ptr);
+		unsigned int block_size = min(num_bytes, PAGE_SIZE - offset);
 
-		memcpy(async->prealloc_buf + write_ptr, data, block_size);
+		memcpy(buf_page_list[page].virt_addr + offset,
+		       data, block_size);
 
 		data += block_size;
 		num_bytes -= block_size;
-
-		write_ptr = 0;
+		write_ptr += block_size;
+		if (write_ptr == async->prealloc_bufsz)
+			write_ptr = 0;
 	}
 }
 
 static void comedi_buf_memcpy_from(struct comedi_subdevice *s,
 				   void *dest, unsigned int nbytes)
 {
-	void *src;
 	struct comedi_async *async = s->async;
+	struct comedi_buf_page *buf_page_list = async->buf_map->page_list;
 	unsigned int read_ptr = async->buf_read_ptr;
 
 	while (nbytes) {
-		unsigned int block_size;
-
-		src = async->prealloc_buf + read_ptr;
-
-		if (nbytes >= async->prealloc_bufsz - read_ptr)
-			block_size = async->prealloc_bufsz - read_ptr;
-		else
-			block_size = nbytes;
+		/*
+		 * Do not copy beyond page boundary.
+		 * Note: prealloc_bufsz is a multiple of PAGE_SIZE.
+		 */
+		unsigned int page = read_ptr >> PAGE_SHIFT;
+		unsigned int offset = offset_in_page(read_ptr);
+		unsigned int block_size = min(nbytes, PAGE_SIZE - offset);
 
-		memcpy(dest, src, block_size);
+		memcpy(dest, buf_page_list[page].virt_addr + offset,
+		       block_size);
 		nbytes -= block_size;
 		dest += block_size;
-		read_ptr = 0;
+		read_ptr += block_size;
+		if (read_ptr == async->prealloc_bufsz)
+			read_ptr = 0;
 	}
 }