linux-kernel - Re: [PATCH] VSOCK: Fix misc device registration

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Message-ID: <20130424153818.GA6916@dtor-ws.eng.vmware.com>
Date:	Wed, 24 Apr 2013 08:38:18 -0700
From:	Dmitry Torokhov <dtor@...are.com>
To:	Asias He <asias@...hat.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Andy King <acking@...are.com>,
	Reilly Grant <grantr@...are.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] VSOCK: Fix misc device registration

On Wed, Apr 24, 2013 at 02:33:52PM +0800, Asias He wrote:
> When we call vsock_core_init to init VSOCK the second time,
> vsock_device.minor still points to the old dynamically allocated minor
> number. misc_register will allocate it for us successfully as if we were
> asking for a static one. However, when other user call misc_register to
> allocate a dynamic minor number, it will give the one used by
> vsock_core_init(), causing this:
> 
>   [  405.470687] WARNING: at fs/sysfs/dir.c:536 sysfs_add_one+0xcc/0xf0()
>   [  405.470689] Hardware name: OptiPlex 790
>   [  405.470690] sysfs: cannot create duplicate filename '/dev/char/10:54'
> 
> Always set vsock_device.minor to MISC_DYNAMIC_MINOR before we
> register.
> 
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Andy King <acking@...are.com>
> Cc: Dmitry Torokhov <dtor@...are.com>
> Cc: Reilly Grant <grantr@...are.com>
> Cc: netdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Asias He <asias@...hat.com>

Well spotted.

Acked-by: Dmitry Torokhov <dtor@...are.com>

> ---
>  net/vmw_vsock/af_vsock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 7f93e2a..4b4db18 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1932,7 +1932,6 @@ static const struct file_operations vsock_device_ops = {
>  
>  static struct miscdevice vsock_device = {
>  	.name		= "vsock",
> -	.minor		= MISC_DYNAMIC_MINOR,
>  	.fops		= &vsock_device_ops,
>  };
>  
> @@ -1942,6 +1941,7 @@ static int __vsock_core_init(void)
>  
>  	vsock_init_tables();
>  
> +	vsock_device.minor = MISC_DYNAMIC_MINOR;
>  	err = misc_register(&vsock_device);
>  	if (err) {
>  		pr_err("Failed to register misc device\n");
> -- 
> 1.8.1.4
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