From: Stefan Richter <stefanr@s5r6.in-berlin.de>
Date: Fri, 15 Aug 2008 22:15:16 +0000 (+0200)
Subject: ieee1394: raw1394: make write() thread-safe
X-Git-Tag: v3.12-rc1~17313^2~19
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f22e52b89e036fd12b9374212da8b5d4a447bd1e;p=kernel%2Fkernel-generic.git

ieee1394: raw1394: make write() thread-safe

Application programs should use a libraw1394 handle only in a single
thread.  The raw1394 driver was apparently relying on this, because it
did nothing to protect its fi->state variable from corruption due to
concurrent accesses.

We now serialize the fi->state accesses.  This affects the write() path.
We re-use the state_mutex which was introduced to protect fi->iso_state
accesses in the ioctl() path.  These paths and accesses are independent
of each other, hence separate mutexes could be used.  But I don't see
much benefit in that.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---

diff --git a/drivers/ieee1394/raw1394.c b/drivers/ieee1394/raw1394.c
index d159442..2cf4ae7 100644
--- a/drivers/ieee1394/raw1394.c
+++ b/drivers/ieee1394/raw1394.c
@@ -2268,6 +2268,8 @@ static ssize_t raw1394_write(struct file *file, const char __user * buffer,
 		return -EFAULT;
 	}
 
+	mutex_lock(&fi->state_mutex);
+
 	switch (fi->state) {
 	case opened:
 		retval = state_opened(fi, req);
@@ -2282,6 +2284,8 @@ static ssize_t raw1394_write(struct file *file, const char __user * buffer,
 		break;
 	}
 
+	mutex_unlock(&fi->state_mutex);
+
 	if (retval < 0) {
 		free_pending_request(req);
 	} else {