[PATCH v2] usb: gadget: f_fs: Use stream_open() for endpoint files

From: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
To: <linux-kernel@vger.kernel.org>, <linux-usb@vger.kernel.org>
Cc: Pavankumar Kondeti <quic_pkondeti@quicinc.com>,
	Felipe Balbi <balbi@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Jens Axboe" <axboe@kernel.dk>, Jack Pham <jackp@codeaurora.org>,
	Peter Chen <peter.chen@nxp.com>,
	Wesley Cheng <wcheng@codeaurora.org>,
	Andrew Gabbasov <andrew_gabbasov@mentor.com>,
	kernel test robot <lkp@intel.com>
Subject: [PATCH v2] usb: gadget: f_fs: Use stream_open() for endpoint files
Date: Thu, 11 Nov 2021 17:45:56 +0530	[thread overview]
Message-ID: <1636632958-22802-1-git-send-email-quic_pkondeti@quicinc.com> (raw)
In-Reply-To: <20211111120636.GA11612@hu-pkondeti-hyd.qualcomm.com>

Function fs endpoint files does not have the notion of file position.
So switch to stream like functionality. This allows concurrent threads
to be blocked in the ffs read/write operations which use ffs_mutex_lock().
The ffs mutex lock deploys interruptible wait. Otherwise, threads are
blocking for the mutex lock in __fdget_pos(). For whatever reason, ff the
host does not send/receive data for longer time, hung task warnings
are observed.

Signed-off-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
---
V2:
- Removed Change-Id tag

 drivers/usb/gadget/function/f_fs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index e20c19a..3c584da 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -614,7 +614,7 @@ static int ffs_ep0_open(struct inode *inode, struct file *file)
 	file->private_data = ffs;
 	ffs_data_opened(ffs);
 
-	return 0;
+	return stream_open(inode, file);
 }
 
 static int ffs_ep0_release(struct inode *inode, struct file *file)
@@ -1154,7 +1154,7 @@ ffs_epfile_open(struct inode *inode, struct file *file)
 	file->private_data = epfile;
 	ffs_data_opened(epfile->ffs);
 
-	return 0;
+	return stream_open(inode, file);
 }
 
 static int ffs_aio_cancel(struct kiocb *kiocb)
-- 
2.7.4

