From 988aad2f111c768c66efc87d073c73ecb32b682c Mon Sep 17 00:00:00 2001
From: Dave Jiang <dave.jiang@intel.com>
Date: Thu, 12 Mar 2020 09:23:53 -0700
Subject: [PATCH] dmaengine: idxd: fix off by one on cdev dwq refcount
Git-commit: 988aad2f111c768c66efc87d073c73ecb32b682c
Patch-mainline: v5.6
References: jsc#SLE-12688
The refcount check for dedicated workqueue (dwq) is off by one and allows
more than 1 user to open the char device. Fix check so only a single user
can open the device.
Fixes: 42d279f9137a ("dmaengine: idxd: add char driver to expose submission portal to userland")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/158403020187.10208.14117394394540710774.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/dma/idxd/cdev.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index df47be612ebb..989b7a25ca61 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -81,9 +81,9 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
dev = &idxd->pdev->dev;
idxd_cdev = &wq->idxd_cdev;
- dev_dbg(dev, "%s called\n", __func__);
+ dev_dbg(dev, "%s called: %d\n", __func__, idxd_wq_refcount(wq));
- if (idxd_wq_refcount(wq) > 1 && wq_dedicated(wq))
+ if (idxd_wq_refcount(wq) > 0 && wq_dedicated(wq))
return -EBUSY;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
--
2.16.4