Merge tag 'asoc-v3.13' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-next

ASoC: Updates for v3.13

 - Further work on the dmaengine helpers, including support for
   configuring the parameters for DMA by reading the capabilities of the
   DMA controller which removes some guesswork and magic numbers fromm
   drivers.
 - A refresh of the documentation.
 - Conversions of many drivers to direct regmap API usage in order to
   allow the ASoC level register I/O code to be removed, this will
   hopefully be completed by v3.14.
 - Support for using async register I/O in DAPM, reducing the time taken
   to implement power transitions on systems that support it.

1 files changed, 37 insertions, 15 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 6b868f0..067e3d3 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -167,10 +167,25 @@ static int __init aio_setup(void)
 }
 __initcall(aio_setup);
 
+static void put_aio_ring_file(struct kioctx *ctx)
+{
+	struct file *aio_ring_file = ctx->aio_ring_file;
+	if (aio_ring_file) {
+		truncate_setsize(aio_ring_file->f_inode, 0);
+
+		/* Prevent further access to the kioctx from migratepages */
+		spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
+		aio_ring_file->f_inode->i_mapping->private_data = NULL;
+		ctx->aio_ring_file = NULL;
+		spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock);
+
+		fput(aio_ring_file);
+	}
+}
+
 static void aio_free_ring(struct kioctx *ctx)
 {
 	int i;
-	struct file *aio_ring_file = ctx->aio_ring_file;
 
 	for (i = 0; i < ctx->nr_pages; i++) {
 		pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
@@ -178,14 +193,10 @@ static void aio_free_ring(struct kioctx *ctx)
 		put_page(ctx->ring_pages[i]);
 	}
 
+	put_aio_ring_file(ctx);
+
 	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
 		kfree(ctx->ring_pages);
-
-	if (aio_ring_file) {
-		truncate_setsize(aio_ring_file->f_inode, 0);
-		fput(aio_ring_file);
-		ctx->aio_ring_file = NULL;
-	}
 }
 
 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
@@ -207,9 +218,8 @@ static int aio_set_page_dirty(struct page *page)
 static int aio_migratepage(struct address_space *mapping, struct page *new,
 			struct page *old, enum migrate_mode mode)
 {
-	struct kioctx *ctx = mapping->private_data;
+	struct kioctx *ctx;
 	unsigned long flags;
-	unsigned idx = old->index;
 	int rc;
 
 	/* Writeback must be complete */
@@ -224,10 +234,23 @@ static int aio_migratepage(struct address_space *mapping, struct page *new,
 
 	get_page(new);
 
-	spin_lock_irqsave(&ctx->completion_lock, flags);
-	migrate_page_copy(new, old);
-	ctx->ring_pages[idx] = new;
-	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+	/* We can potentially race against kioctx teardown here.  Use the
+	 * address_space's private data lock to protect the mapping's
+	 * private_data.
+	 */
+	spin_lock(&mapping->private_lock);
+	ctx = mapping->private_data;
+	if (ctx) {
+		pgoff_t idx;
+		spin_lock_irqsave(&ctx->completion_lock, flags);
+		migrate_page_copy(new, old);
+		idx = old->index;
+		if (idx < (pgoff_t)ctx->nr_pages)
+			ctx->ring_pages[idx] = new;
+		spin_unlock_irqrestore(&ctx->completion_lock, flags);
+	} else
+		rc = -EBUSY;
+	spin_unlock(&mapping->private_lock);
 
 	return rc;
 }
@@ -617,8 +640,7 @@ out_freepcpu:
 out_freeref:
 	free_percpu(ctx->users.pcpu_count);
 out_freectx:
-	if (ctx->aio_ring_file)
-		fput(ctx->aio_ring_file);
+	put_aio_ring_file(ctx);
 	kmem_cache_free(kioctx_cachep, ctx);
 	pr_debug("error allocating ioctx %d\n", err);
 	return ERR_PTR(err);