* [PATCH v3] dmaengine: idxd: fix cdev locking for open and release
@ 2020-06-22 20:38 Dave Jiang
2020-06-24 5:48 ` Vinod Koul
0 siblings, 1 reply; 2+ messages in thread
From: Dave Jiang @ 2020-06-22 20:38 UTC (permalink / raw)
To: vkoul; +Cc: Nikhil Rao, dmaengine
From: Nikhil Rao <nikhil.rao@intel.com>
add the wq lock in cdev open and release call. This fixes
race conditions observed in the open and close routines.
Fixes: 42d279f9137a ("dmaengine: idxd: add char driver to expose submission portal to userland")
Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v3:
- Caught uninit rc variable.
v2:
- Added kbuild fix from Dan Carpenter re:
smatch warnings:
drivers/dma/idxd/cdev.c:106 idxd_cdev_open() error: uninitialized symbol 'ctx'.
drivers/dma/idxd/cdev.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index ff49847e37a8..cb376cf6a2d2 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -74,6 +74,7 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
struct idxd_device *idxd;
struct idxd_wq *wq;
struct device *dev;
+ int rc = 0;
wq = inode_wq(inode);
idxd = wq->idxd;
@@ -81,17 +82,27 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
dev_dbg(dev, "%s called: %d\n", __func__, idxd_wq_refcount(wq));
- if (idxd_wq_refcount(wq) > 0 && wq_dedicated(wq))
- return -EBUSY;
-
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
return -ENOMEM;
+ mutex_lock(&wq->wq_lock);
+
+ if (idxd_wq_refcount(wq) > 0 && wq_dedicated(wq)) {
+ rc = -EBUSY;
+ goto failed;
+ }
+
ctx->wq = wq;
filp->private_data = ctx;
idxd_wq_get(wq);
+ mutex_unlock(&wq->wq_lock);
return 0;
+
+ failed:
+ mutex_unlock(&wq->wq_lock);
+ kfree(ctx);
+ return rc;
}
static int idxd_cdev_release(struct inode *node, struct file *filep)
@@ -105,7 +116,9 @@ static int idxd_cdev_release(struct inode *node, struct file *filep)
filep->private_data = NULL;
kfree(ctx);
+ mutex_lock(&wq->wq_lock);
idxd_wq_put(wq);
+ mutex_unlock(&wq->wq_lock);
return 0;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v3] dmaengine: idxd: fix cdev locking for open and release
2020-06-22 20:38 [PATCH v3] dmaengine: idxd: fix cdev locking for open and release Dave Jiang
@ 2020-06-24 5:48 ` Vinod Koul
0 siblings, 0 replies; 2+ messages in thread
From: Vinod Koul @ 2020-06-24 5:48 UTC (permalink / raw)
To: Dave Jiang; +Cc: Nikhil Rao, dmaengine
On 22-06-20, 13:38, Dave Jiang wrote:
> From: Nikhil Rao <nikhil.rao@intel.com>
>
> add the wq lock in cdev open and release call. This fixes
> race conditions observed in the open and close routines.
>
> Fixes: 42d279f9137a ("dmaengine: idxd: add char driver to expose submission portal to userland")
>
Please don't keep blank lines b/w Fixes and S-o-b lines!
> Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Applied after fixing the blank line, thanks
--
~Vinod
^ permalink raw reply [flat|nested] 2+ messages in thread
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