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

Yuanhan Liu yuanhan.liu at linux.intel.com
Mon Nov 9 13:58:25 CET 2015


On Mon, Nov 09, 2015 at 10:19:54AM +0000, Chi, Xiaobo (Nokia - CN/Hangzhou) wrote:
> 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 .

Good to know and thanks for the explanation. It's well explained, and
you should put them (including below example) to commit log. With the
detailed issue explanation, and steps to reproduce, it just gives
your patch more chance to get reviewed (and merged).

And, don't forget to title your patch with "vhost: fix ..." preifx.

FYI, there is another custom for a fix patch in DPDK community: adding
an extra line like following to indicate the latest commit introduces
such bug:

    Fixes: 62dbd2ffea9a ("ethdev: add more flow director modes")


Which is generated with following git alias (check http://dpdk.org/dev
for more information):

    [alias]
         fixline = log -1 --abbrev=12 --format='Fixes: %h (\"%s\")'


So, would you please send v2?

	--yliu

> 
> root at 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 at distro:~/test$ modinfo kmod_test
> modinfo: ERROR: Module kmod_test not found.
> root at 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 at distro:~/test$ dmesg -c
> root at 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 at distro:~/test$ insmod ./eventfd_link.ko 
> insmod: ERROR: could not insert module ./eventfd_link.ko: Device or resource busy
> root at distro:~/test$ dmesg -c
> 
> brgs,
> Xiaobo Chi
> 
> 
> -----Original Message-----
> From: dev [mailto:dev-bounces at 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 at dpdk.org; changchun.ouyang at 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 at dpdk.org] On Behalf Of EXT Yuanhan Liu
> Sent: Monday, November 09, 2015 12:23 PM
> To: Chi, Xiaobo (Nokia - CN/Hangzhou)
> Cc: dev at dpdk.org; changchun.ouyang at 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 at 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


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