Re: [dpdk-dev] [PATCH] vhost: eventfd_link's minor number shall be specified

["Chi, Xiaobo (Nokia - CN/Hangzhou)" <xiaobo.chi@nokia.com>]

Hi,

And following is a test by me, we can see that if I firstly insert my kmod_test.ko, then insert eventfd_link.ko, error will happen with hint " Device or resource busy". This is because the default minor device number, 0, has been occupied by my kmod_test.ko .

root@distro:~/test$ lsmod
Module                  Size  Used by
kmod_test                927  0 
vboxsf                 35930  4 
vboxguest             222130  1 vboxsf
microcode              10315  0 
autofs4                25051  0 
root@distro:~/test$ modinfo kmod_test
modinfo: ERROR: Module kmod_test not found.
root@distro:~/test$ modinfo kmod_test.ko
filename:       /root/test/kmod_test.ko
alias:          devname:test
description:    my test
author:         Xiaobo Chi
license:        GPL v2
version:        0.0.1
srcversion:     C2BDEBC81A17F8197C7C44A
depends:        
vermagic:       3.18.9-pc64-distro.git-v1.7 SMP mod_unload 
root@distro:~/test$ dmesg -c
root@distro:~/test$ ls
eventfd_link.ko  kmod_test.ko     kmod_test.mod.o  main    Makefile       Module.symvers
kmod_test.c      kmod_test.mod.c  kmod_test.o      main.c  modules.order
root@distro:~/test$ insmod ./eventfd_link.ko 
insmod: ERROR: could not insert module ./eventfd_link.ko: Device or resource busy
root@distro:~/test$ dmesg -c

brgs,
Xiaobo Chi


-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of EXT Chi, Xiaobo (Nokia - CN/Hangzhou)
Sent: Monday, November 09, 2015 6:03 PM
To: EXT Yuanhan Liu
Cc: dev@dpdk.org; changchun.ouyang@intel.com
Subject: Re: [dpdk-dev] [PATCH] vhost: eventfd_link's minor number shall be specified

Hi,
For miscdevices, the major device_no is same, so the minor device_no should be set to ditinguish different misc devices;  if not set the minor, it may fail while insmod due to the default minor value, 0, has been used by other miscdevice. MISC_DYNAMIC_MINOR means to let Linux kernel dynamically assign one minor devide number while loading.
You can refer to the kni_misc.c

Brgs,
Chi Xiaobo

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of EXT Yuanhan Liu
Sent: Monday, November 09, 2015 12:23 PM
To: Chi, Xiaobo (Nokia - CN/Hangzhou)
Cc: dev@dpdk.org; changchun.ouyang@intel.com
Subject: Re: [dpdk-dev] [PATCH] vhost: eventfd_link's minor number shall be specified

On Fri, Nov 06, 2015 at 02:04:37PM +0800, Xiaobo Chi wrote:
>  eventfd_link_misc's minor number shall be MISC_DYNAMIC_MINOR to let Linux kernel dynamically assign one while loading.

For such (fix) patch, I'd like to see what exact issue your patch fixes.

And if it fixes an issue, you'd better title your patch with something
like "vhost: fix ...", so that it's likely Thomas will put it into
high priority.

	--yliu

> 
> Signed-off-by: Xiaobo Chi <xiaobo.chi@nokia.com>
> ---
>  lib/librte_vhost/eventfd_link/eventfd_link.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/librte_vhost/eventfd_link/eventfd_link.c b/lib/librte_vhost/eventfd_link/eventfd_link.c
> index c54a938..4b05b5a 100644
> --- a/lib/librte_vhost/eventfd_link/eventfd_link.c
> +++ b/lib/librte_vhost/eventfd_link/eventfd_link.c
> @@ -249,6 +249,7 @@ static const struct file_operations eventfd_link_fops = {
>  
>  
>  static struct miscdevice eventfd_link_misc = {
> +	.minor = MISC_DYNAMIC_MINOR,
>  	.name = "eventfd-link",
>  	.fops = &eventfd_link_fops,
>  };
> -- 
> 1.9.4.msysgit.2