diff mbox series

[v4,14/16] rpmsg: char: introduce a RPMsg driver for the RPMsg char device

Message ID 20210217132905.1485-15-arnaud.pouliquen@foss.st.com (mailing list archive)
State Superseded
Headers show
Series introduce a generic IOCTL interface for RPMsg channels management | expand

Commit Message

Arnaud POULIQUEN Feb. 17, 2021, 1:29 p.m. UTC 
A RPMsg char device allows to probe the endpoint device on a remote name
service announcement. With this patch the /dev/rpmsgX interface is created
either by a user application or by the remote firmware.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
---
 drivers/rpmsg/rpmsg_char.c | 63 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

Comments

Dan Carpenter Feb. 18, 2021, 12:33 p.m. UTC | #1 
Hi Arnaud,

url:    https://github.com/0day-ci/linux/commits/Arnaud-Pouliquen/introduce-a-generic-IOCTL-interface-for-RPMsg-channels-management/20210217-214044
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f40ddce88593482919761f74910f42f4b84c004b
config: riscv-randconfig-m031-20210215 (attached as .config)
compiler: riscv32-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/rpmsg/rpmsg_char.c:429 rpmsg_chrdev_probe() error: we previously assumed 'rpdev->ept' could be null (see line 423)

vim +429 drivers/rpmsg/rpmsg_char.c

7337f30f7a4426 Arnaud Pouliquen 2021-02-17  413  static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  414  {
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  415  	struct rpmsg_channel_info chinfo;
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  416  	struct rpmsg_eptdev *eptdev;
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  417  
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  418  	memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME));
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  419  	chinfo.src = rpdev->src;
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  420  	chinfo.dst = rpdev->dst;
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  421  
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  422  	eptdev = __rpmsg_chrdev_create_eptdev(rpdev, &rpdev->dev, chinfo);
7337f30f7a4426 Arnaud Pouliquen 2021-02-17 @423  	if (IS_ERR(eptdev) && rpdev->ept) {
                                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This condition is strange.

7337f30f7a4426 Arnaud Pouliquen 2021-02-17  424  		rpmsg_destroy_ept(rpdev->ept);
                                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
What?  Why are we undoing this when it's not something that we created?
This seems like a layering violation...

7337f30f7a4426 Arnaud Pouliquen 2021-02-17  425  		return PTR_ERR(eptdev);
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  426  	}
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  427  
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  428  	/* Set the private field of the default endpoint to retrieve context on callback. */
7337f30f7a4426 Arnaud Pouliquen 2021-02-17 @429  	rpdev->ept->priv = eptdev;
                                                        ^^^^^^^^^^^^^^^^^^^^^^^^^
If "rpdev->ept" is NULL this will Oops.  If "eptdev" is an error pointer
that seems wrong as well.

7337f30f7a4426 Arnaud Pouliquen 2021-02-17  430  
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  431  	return 0;
7337f30f7a4426 Arnaud Pouliquen 2021-02-17  432  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Arnaud POULIQUEN Feb. 18, 2021, 5:52 p.m. UTC | #2 
Hi Dan,

On 2/18/21 1:33 PM, Dan Carpenter wrote:
> Hi Arnaud,
> 
> url:    https://github.com/0day-ci/linux/commits/Arnaud-Pouliquen/introduce-a-generic-IOCTL-interface-for-RPMsg-channels-management/20210217-214044
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f40ddce88593482919761f74910f42f4b84c004b
> config: riscv-randconfig-m031-20210215 (attached as .config)
> compiler: riscv32-linux-gcc (GCC) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> smatch warnings:
> drivers/rpmsg/rpmsg_char.c:429 rpmsg_chrdev_probe() error: we previously assumed 'rpdev->ept' could be null (see line 423)
> 
> vim +429 drivers/rpmsg/rpmsg_char.c
> 
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  413  static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  414  {
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  415  	struct rpmsg_channel_info chinfo;
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  416  	struct rpmsg_eptdev *eptdev;
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  417  
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  418  	memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME));
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  419  	chinfo.src = rpdev->src;
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  420  	chinfo.dst = rpdev->dst;
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  421  
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  422  	eptdev = __rpmsg_chrdev_create_eptdev(rpdev, &rpdev->dev, chinfo);
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17 @423  	if (IS_ERR(eptdev) && rpdev->ept) {
>                                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This condition is strange.

> 
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  424  		rpmsg_destroy_ept(rpdev->ept);
>                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> What?  Why are we undoing this when it's not something that we created?
> This seems like a layering violation...

Right,something is not clean here, I need to crosscheck, but should be
	if (IS_ERR(eptdev) && ) {
		return PTR_ERR(eptdev);
	}
The endpoint is already destroyed by rpmsg_dev_probe on error.

> 
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  425  		return PTR_ERR(eptdev);
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  426  	}
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  427  
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  428  	/* Set the private field of the default endpoint to retrieve context on callback. */
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17 @429  	rpdev->ept->priv = eptdev;
>                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^
> If "rpdev->ept" is NULL this will Oops.  If "eptdev" is an error pointer
> that seems wrong as well.

rpdev->ept is set in rpmsg_dev_probe as the callback is defined so can not be
null, so probably a false positive here.
eptdev can not be an error pointer here for the same reason.

Anyway adding a check on the pointer, is not a big work and can prevent from
future issue.

As consequence of you multi-reports I have installed your smatch tool on my PC
and added it in my compilation chain. :)

Thanks for the review and the tool,
Arnaud

> 
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  430  
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  431  	return 0;
> 7337f30f7a4426 Arnaud Pouliquen 2021-02-17  432  }
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>
diff mbox series

Patch

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 66dcb8845d6c..d5aa874865f7 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -28,6 +28,8 @@ 
 
 #define RPMSG_DEV_MAX	(MINORMASK + 1)
 
+#define RPMSG_CHAR_DEVNAME "rpmsg-raw"
+
 static dev_t rpmsg_major;
 static struct class *rpmsg_class;
 
@@ -408,6 +410,51 @@  int rpmsg_chrdev_create_eptdev(struct rpmsg_device *rpdev, struct device *parent
 }
 EXPORT_SYMBOL(rpmsg_chrdev_create_eptdev);
 
+static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
+{
+	struct rpmsg_channel_info chinfo;
+	struct rpmsg_eptdev *eptdev;
+
+	memcpy(chinfo.name, RPMSG_CHAR_DEVNAME, sizeof(RPMSG_CHAR_DEVNAME));
+	chinfo.src = rpdev->src;
+	chinfo.dst = rpdev->dst;
+
+	eptdev = __rpmsg_chrdev_create_eptdev(rpdev, &rpdev->dev, chinfo);
+	if (IS_ERR(eptdev) && rpdev->ept) {
+		rpmsg_destroy_ept(rpdev->ept);
+		return PTR_ERR(eptdev);
+	}
+
+	/* Set the private field of the default endpoint to retrieve context on callback. */
+	rpdev->ept->priv = eptdev;
+
+	return 0;
+}
+
+static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
+{
+	int ret;
+
+	ret = device_for_each_child(&rpdev->dev, NULL, rpmsg_chrdev_eptdev_destroy);
+	if (ret)
+		dev_warn(&rpdev->dev, "failed to destroy endpoints: %d\n", ret);
+}
+
+static struct rpmsg_device_id rpmsg_chrdev_id_table[] = {
+	{ .name	= RPMSG_CHAR_DEVNAME },
+	{ },
+};
+
+static struct rpmsg_driver rpmsg_chrdev_driver = {
+	.probe = rpmsg_chrdev_probe,
+	.remove = rpmsg_chrdev_remove,
+	.id_table = rpmsg_chrdev_id_table,
+	.callback = rpmsg_ept_cb,
+	.drv = {
+		.name = "rpmsg_chrdev",
+	},
+};
+
 static int rpmsg_chrdev_init(void)
 {
 	int ret;
@@ -422,9 +469,23 @@  static int rpmsg_chrdev_init(void)
 	if (IS_ERR(rpmsg_class)) {
 		pr_err("failed to create rpmsg class\n");
 		unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
-		return PTR_ERR(rpmsg_class);
+		ret = PTR_ERR(rpmsg_class);
+		goto free_region;
 	}
 
+	ret = register_rpmsg_driver(&rpmsg_chrdev_driver);
+	if (ret < 0) {
+		pr_err("rpmsg raw: failed to register rpmsg driver\n");
+		goto free_class;
+	}
+
+	return 0;
+
+free_class:
+	class_destroy(rpmsg_class);
+free_region:
+	unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
+
 	return ret;
 }
 postcore_initcall(rpmsg_chrdev_init);