Hi Mathieu,
On 1/14/21 8:05 PM, Mathieu Poirier wrote:
> On Wed, Jan 06, 2021 at 02:37:14PM +0100, Arnaud Pouliquen wrote:
>> The rpmsg_create_ept function is invoked when the device is opened.
>> As only one endpoint must be created per device. It is not
>> possible to open the same device twice.
>> The fix consists in returning -EBUSY when device is already
>> opened.
>>
>> Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
>> Signed-off-by: Arnaud Pouliquen <[email protected]>
>> ---
>> drivers/rpmsg/rpmsg_char.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
>> index 4bbbacdbf3bb..360a1ab0a9c4 100644
>> --- a/drivers/rpmsg/rpmsg_char.c
>> +++ b/drivers/rpmsg/rpmsg_char.c
>> @@ -127,6 +127,9 @@ static int rpmsg_eptdev_open(struct inode *inode, struct
>> file *filp)
>> struct rpmsg_device *rpdev = eptdev->rpdev;
>> struct device *dev = &eptdev->dev;
>>
>> + if (eptdev->ept)
>> + return -EBUSY;
>> +
>
> I rarely had to work so hard to review a 2 line patch...
That means that my commit description was not enough explicit...
>
> As far as I can tell the actual code is doing the right thing. If user space
> is
> trying to open the same eptdev more than once function rpmsg_create_ept()
> should
> complain and the operation denied, wich is what the current code is doing.
>
> There is currently two customers for this API - SMD and GLINK. The SMD code
> is
> quite clear that if the channel is already open, the operation will be
> denied [1]. The GLINK code isn't as clear but the fact that it returns NULL
> on
> error conditions [2] is a good indication that things are working the same
> way.
>
> What kind of use case are you looking to address? Is there any way you can
> use
> rpdev->ops->create_ept() as it is currently done?
This patch was part of the IOCTL rpmsg series. I sent it separately at Bjorn's
request [1].
I detect the issue using the RPMSG_ADDR_ANY for the source address when tested
it with the rpmsf_virtio bus. In this case at each sys open of the device, a new
endpoint is created because a new source address is allocated.
[1]https://patchwork.kernel.org/project/linux-remoteproc/patch/[email protected]/
Thanks,
Arnaud
>
> Thanks,
> Mathieu
>
> [1].
> https://elixir.bootlin.com/linux/v5.11-rc3/source/drivers/rpmsg/qcom_smd.c#L920
> [2].
> https://elixir.bootlin.com/linux/v5.11-rc3/source/drivers/rpmsg/qcom_glink_native.c#L1149
>
>> get_device(dev);
>>
>> ept = rpmsg_create_ept(rpdev, rpmsg_ept_cb, eptdev, eptdev->chinfo);
>> --
>> 2.17.1
>>
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