From: Dongwoo <dwoo08.lee@samsung.com>
Date: Fri, 26 Oct 2018 01:41:41 +0000 (+0900)
Subject: LOCAL / usb: gadget: f_fs: Limit data buffer size to a single page
X-Git-Tag: submit/tizen/20190129.052023~20
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=badec43b11fb3adb4ea25745c568f2e828ff8669;p=profile%2Fcommon%2Fplatform%2Fkernel%2Flinux-artik7.git

LOCAL / usb: gadget: f_fs: Limit data buffer size to a single page

 Large size request from sdbd usually causes memory allocation failure
in case of memory shortage. The failure is not handled by sdbd
properly and thus it makes sdbd a hung state. To prevent this
situation, this patch limits data buffer size to a single page so as
to guarantee memory allocation success.

* This is WORKAROUND solution for just use case of sdbd, it should be
  reverted when the advanced dma solution is applied to f_fs *

Change-Id: Ib917c3aef2b00a3e00a3d87ca6d6940307038aa1
Signed-off-by: Dongwoo <dwoo08.lee@samsung.com>
---

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 4800bb22cdd6..009a776c372a 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -736,6 +736,14 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
 			return -ESHUTDOWN;
 		}
 		data_len = iov_iter_count(&io_data->data);
+
+		/*
+		 * WORKAROUND:
+		 * To prevent memory allocation failure of big size request,
+		 * limits data buffer size to a single page.
+		 */
+		data_len = (data_len > PAGE_SIZE) ? PAGE_SIZE : data_len;
+
 		/*
 		 * Controller may require buffer size to be aligned to
 		 * maxpacketsize of an out endpoint.