[PATCH 0/5] xen: cleanup detection of non-essential pv devices

[PATCH 0/5] xen: cleanup detection of non-essential pv devices

[Juergen Gross]

Today the non-essential pv devices are hard coded in the xenbus driver
and this list is lacking multiple entries.

This series reworks the detection logic of non-essential devices by
adding a flag for that purpose to struct xenbus_driver.

Juergen Gross (5):
  xen: add "not_essential" flag to struct xenbus_driver
  xen: flag xen_drm_front to be not essential for system boot
  xen: flag hvc_xen to be not essential for system boot
  xen: flag pvcalls-front to be not essential for system boot
  xen: flag xen_snd_front to be not essential for system boot

 drivers/gpu/drm/xen/xen_drm_front.c        |  1 +
 drivers/input/misc/xen-kbdfront.c          |  1 +
 drivers/tty/hvc/hvc_xen.c                  |  1 +
 drivers/video/fbdev/xen-fbfront.c          |  1 +
 drivers/xen/pvcalls-front.c                |  1 +
 drivers/xen/xenbus/xenbus_probe_frontend.c | 14 +++-----------
 include/xen/xenbus.h                       |  1 +
 sound/xen/xen_snd_front.c                  |  1 +
 8 files changed, 10 insertions(+), 11 deletions(-)

-- 
2.26.2

[PATCH 5/5] xen: flag xen_snd_front to be not essential for system boot

[Juergen Gross]

The Xen pv sound driver is not essential for booting. Set the respective
flag.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 sound/xen/xen_snd_front.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/xen/xen_snd_front.c b/sound/xen/xen_snd_front.c
index 2cb0a19be2b8..7be9fbcf788f 100644
--- a/sound/xen/xen_snd_front.c
+++ b/sound/xen/xen_snd_front.c
@@ -358,6 +358,7 @@ static struct xenbus_driver xen_driver = {
 	.probe = xen_drv_probe,
 	.remove = xen_drv_remove,
 	.otherend_changed = sndback_changed,
+	.not_essential = true;
 };
 
 static int __init xen_drv_init(void)
-- 
2.26.2

Re: [PATCH 0/5] xen: cleanup detection of non-essential pv devices

[Jan Beulich]

On 22.10.2021 08:47, Juergen Gross wrote:
> Today the non-essential pv devices are hard coded in the xenbus driver
> and this list is lacking multiple entries.
> 
> This series reworks the detection logic of non-essential devices by
> adding a flag for that purpose to struct xenbus_driver.

I'm wondering whether it wouldn't better be the other way around: The
(hopefully few) essential ones get flagged, thus also making it more
prominent during patch review that a flag gets added (and justification
provided), instead of having to spot the lack of a flag getting set.

Jan

Re: [PATCH 5/5] xen: flag xen_snd_front to be not essential for system boot

[Oleksandr Andrushchenko]

Hi, Juergen!

On 22.10.21 09:48, Juergen Gross wrote:
> The Xen pv sound driver is not essential for booting. Set the respective
> flag.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> ---
>   sound/xen/xen_snd_front.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/sound/xen/xen_snd_front.c b/sound/xen/xen_snd_front.c
> index 2cb0a19be2b8..7be9fbcf788f 100644
> --- a/sound/xen/xen_snd_front.c
> +++ b/sound/xen/xen_snd_front.c
> @@ -358,6 +358,7 @@ static struct xenbus_driver xen_driver = {
>   	.probe = xen_drv_probe,
>   	.remove = xen_drv_remove,
>   	.otherend_changed = sndback_changed,
> +	.not_essential = true;
>   };
>   
>   static int __init xen_drv_init(void)

Re: [PATCH 0/5] xen: cleanup detection of non-essential pv devices

[Juergen Gross]

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On 22.10.21 09:24, Jan Beulich wrote:
> On 22.10.2021 08:47, Juergen Gross wrote:
>> Today the non-essential pv devices are hard coded in the xenbus driver
>> and this list is lacking multiple entries.
>>
>> This series reworks the detection logic of non-essential devices by
>> adding a flag for that purpose to struct xenbus_driver.
> 
> I'm wondering whether it wouldn't better be the other way around: The
> (hopefully few) essential ones get flagged, thus also making it more
> prominent during patch review that a flag gets added (and justification
> provided), instead of having to spot the lack of a flag getting set.

Not flagging a non-essential one is less problematic than not flagging
an essential driver IMO.

For some drivers I'm on the edge, BTW. The pv 9pfs driver ought to be
non-essential in most cases, but there might be use cases where it is
needed, so I didn't set its non_essential flag.

Same applies to pv-usb and maybe pv-scsi, while pv-tpm probably really
is essential.

With the current series I'm ending up with 6 non-essential drivers and
6 essential ones, so either way needs the same number of drivers
modified.


Juergen

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Re: [PATCH 5/5] xen: flag xen_snd_front to be not essential for system boot

[kernel test robot]

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Hi Juergen,

I love your patch! Yet something to improve:

[auto build test ERROR on xen-tip/linux-next]
[also build test ERROR on tty/tty-testing tiwai-sound/for-next hid/for-next linus/master v5.15 next-20211106]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Juergen-Gross/xen-cleanup-detection-of-non-essential-pv-devices/20211022-145043
base:   https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git linux-next
config: arm64-randconfig-r005-20211025 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project a461fa64bb37cffd73f683c74f6b0780379fc2ca)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://github.com/0day-ci/linux/commit/ed8f15a6cafc5414c3821aad66273c580034c3c0
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Juergen-Gross/xen-cleanup-detection-of-non-essential-pv-devices/20211022-145043
        git checkout ed8f15a6cafc5414c3821aad66273c580034c3c0
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash sound/xen/

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

All errors (new ones prefixed by >>):

>> sound/xen/xen_snd_front.c:361:23: error: unexpected ';' before '}'
           .not_essential = true;
                                ^
   1 error generated.


vim +361 sound/xen/xen_snd_front.c

   355	
   356	static struct xenbus_driver xen_driver = {
   357		.ids = xen_drv_ids,
   358		.probe = xen_drv_probe,
   359		.remove = xen_drv_remove,
   360		.otherend_changed = sndback_changed,
 > 361		.not_essential = true;
   362	};
   363	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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Re: [PATCH 0/5] xen: cleanup detection of non-essential pv devices

[Juergen Gross]

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On 22.10.21 08:47, Juergen Gross wrote:
> Today the non-essential pv devices are hard coded in the xenbus driver
> and this list is lacking multiple entries.
> 
> This series reworks the detection logic of non-essential devices by
> adding a flag for that purpose to struct xenbus_driver.
> 
> Juergen Gross (5):
>    xen: add "not_essential" flag to struct xenbus_driver
>    xen: flag xen_drm_front to be not essential for system boot
>    xen: flag hvc_xen to be not essential for system boot
>    xen: flag pvcalls-front to be not essential for system boot
>    xen: flag xen_snd_front to be not essential for system boot
> 
>   drivers/gpu/drm/xen/xen_drm_front.c        |  1 +
>   drivers/input/misc/xen-kbdfront.c          |  1 +
>   drivers/tty/hvc/hvc_xen.c                  |  1 +
>   drivers/video/fbdev/xen-fbfront.c          |  1 +
>   drivers/xen/pvcalls-front.c                |  1 +
>   drivers/xen/xenbus/xenbus_probe_frontend.c | 14 +++-----------
>   include/xen/xenbus.h                       |  1 +
>   sound/xen/xen_snd_front.c                  |  1 +
>   8 files changed, 10 insertions(+), 11 deletions(-)
> 

Any further comments?


Juergen

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Re: [PATCH 0/5] xen: cleanup detection of non-essential pv devices

[Boris Ostrovsky]

On 11/22/21 3:20 AM, Juergen Gross wrote:
> On 22.10.21 08:47, Juergen Gross wrote:
>> Today the non-essential pv devices are hard coded in the xenbus driver
>> and this list is lacking multiple entries.
>>
>> This series reworks the detection logic of non-essential devices by
>> adding a flag for that purpose to struct xenbus_driver.
>>
>> Juergen Gross (5):
>>    xen: add "not_essential" flag to struct xenbus_driver
>>    xen: flag xen_drm_front to be not essential for system boot
>>    xen: flag hvc_xen to be not essential for system boot
>>    xen: flag pvcalls-front to be not essential for system boot
>>    xen: flag xen_snd_front to be not essential for system boot
>>
>>   drivers/gpu/drm/xen/xen_drm_front.c        |  1 +
>>   drivers/input/misc/xen-kbdfront.c          |  1 +
>>   drivers/tty/hvc/hvc_xen.c                  |  1 +
>>   drivers/video/fbdev/xen-fbfront.c          |  1 +
>>   drivers/xen/pvcalls-front.c                |  1 +
>>   drivers/xen/xenbus/xenbus_probe_frontend.c | 14 +++-----------
>>   include/xen/xenbus.h                       |  1 +
>>   sound/xen/xen_snd_front.c                  |  1 +
>>   8 files changed, 10 insertions(+), 11 deletions(-)
>>
>
> Any further comments?
>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>


(I'll fix the semicolon typo in the last patch, no need to resend)

Re: [PATCH 0/5] xen: cleanup detection of non-essential pv devices

[Boris Ostrovsky]

On 11/22/21 3:20 AM, Juergen Gross wrote:
> On 22.10.21 08:47, Juergen Gross wrote:
>> Today the non-essential pv devices are hard coded in the xenbus driver
>> and this list is lacking multiple entries.
>>
>> This series reworks the detection logic of non-essential devices by
>> adding a flag for that purpose to struct xenbus_driver.
>>
>> Juergen Gross (5):
>>    xen: add "not_essential" flag to struct xenbus_driver
>>    xen: flag xen_drm_front to be not essential for system boot
>>    xen: flag hvc_xen to be not essential for system boot
>>    xen: flag pvcalls-front to be not essential for system boot
>>    xen: flag xen_snd_front to be not essential for system boot
>>
>>   drivers/gpu/drm/xen/xen_drm_front.c        |  1 +
>>   drivers/input/misc/xen-kbdfront.c          |  1 +
>>   drivers/tty/hvc/hvc_xen.c                  |  1 +
>>   drivers/video/fbdev/xen-fbfront.c          |  1 +
>>   drivers/xen/pvcalls-front.c                |  1 +
>>   drivers/xen/xenbus/xenbus_probe_frontend.c | 14 +++-----------
>>   include/xen/xenbus.h                       |  1 +
>>   sound/xen/xen_snd_front.c                  |  1 +
>>   8 files changed, 10 insertions(+), 11 deletions(-)
>>
>



Applied to for-linus-5.16c


-boris