Avoid recursing into ashmem_shrink from within ashmem itself.

Signed-off-by: Robert Love <rlove@rlove.org>

 ashmem.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- linux-base/drivers/staging/android/ashmem.c	2013-04-25 10:58:33.251469472 -0400
+++ linux/drivers/staging/android/ashmem.c	2013-04-25 11:02:29.420644278 -0400
@@ -361,7 +361,11 @@
 	if (!sc->nr_to_scan)
 		return lru_count;
 
-	mutex_lock(&ashmem_mutex);
+	/* avoid recursing into this code from within ashmem itself */
+	if (!mutex_trylock(&ashmem_mutex)) {
+		return -1;
+	}
+
 	list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
 		struct inode *inode = range->asma->file->f_dentry->d_inode;
 		loff_t start = range->pgstart * PAGE_SIZE;