From cbf83cc5a29dba480cf1ba1c5e3417a0d4a31410 Mon Sep 17 00:00:00 2001
From: Rodolfo Giometti <giometti@linux.it>
Date: Wed, 11 Nov 2009 14:26:52 -0800
Subject: [PATCH] pps: locking scheme fix up for PPS_GETPARAMS
Userland programs may read/write PPS parameters at same time and these
operations may corrupt PPS data.
Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Tested-by: Reg Clemens <clemens@dwf.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/pps/pps.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index fea17e7805e9d..ca5183bdad85f 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -71,9 +71,14 @@ static long pps_cdev_ioctl(struct file *file,
case PPS_GETPARAMS:
pr_debug("PPS_GETPARAMS: source %d\n", pps->id);
- /* Return current parameters */
- err = copy_to_user(uarg, &pps->params,
- sizeof(struct pps_kparams));
+ spin_lock_irq(&pps->lock);
+
+ /* Get the current parameters */
+ params = pps->params;
+
+ spin_unlock_irq(&pps->lock);
+
+ err = copy_to_user(uarg, ¶ms, sizeof(struct pps_kparams));
if (err)
return -EFAULT;
--
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