From: Bjorn Bringert <bringert@android.com>
Date: Thu, 15 Apr 2010 09:04:01 +0000 (+0100)
Subject: Implement read(2) in ashmem driver
X-Git-Tag: firefly_0821_release~9833^2~5^2~186
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7dc0be13b07ded70ece4f602c530dec93d7a9c9c;p=firefly-linux-kernel-4.4.55.git

Implement read(2) in ashmem driver

Bug: 2595601
Change-Id: I47c0016f594f9354fb8658ccb26e3d395bcb137b
Signed-off-by: Bjorn Bringert <bringert@android.com>
---

diff --git a/mm/ashmem.c b/mm/ashmem.c
index 230810f9387c..04e886e2c909 100644
--- a/mm/ashmem.c
+++ b/mm/ashmem.c
@@ -211,6 +211,31 @@ static int ashmem_release(struct inode *ignored, struct file *file)
 	return 0;
 }
 
+static ssize_t ashmem_read(struct file *file, char __user *buf,
+			   size_t len, loff_t *pos)
+{
+	struct ashmem_area *asma = file->private_data;
+	int ret = 0;
+
+	mutex_lock(&ashmem_mutex);
+
+	/* If size is not set, or set to 0, always return EOF. */
+	if (asma->size == 0) {
+		goto out;
+        }
+
+	if (!asma->file) {
+		ret = -EBADF;
+		goto out;
+	}
+
+	ret = asma->file->f_op->read(asma->file, buf, len, pos);
+
+out:
+	mutex_unlock(&ashmem_mutex);
+	return ret;
+}
+
 static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct ashmem_area *asma = file->private_data;
@@ -604,6 +629,7 @@ static struct file_operations ashmem_fops = {
 	.owner = THIS_MODULE,
 	.open = ashmem_open,
 	.release = ashmem_release,
+        .read = ashmem_read,
 	.mmap = ashmem_mmap,
 	.unlocked_ioctl = ashmem_ioctl,
 	.compat_ioctl = ashmem_ioctl,