FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

[gregkh]

The patch below does not apply to the 4.16-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 1c1a2ee1b53b006754073eefc65d2b2cedb5264b Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Thu, 17 May 2018 23:33:26 +0800
Subject: [PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n

Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
returns the return value of debugfs_create_dir() to bcache_init(). When
CONFIG_DEBUG_FS=n, bch_debug_init() always returns 1 and makes
bcache_init() failedi.

This patch makes bch_debug_init() always returns 0 if CONFIG_DEBUG_FS=n,
so bcache can continue to work for the kernels which don't have debugfs
enanbled.

Changelog:
v4: Add Acked-by from Kent Overstreet.
v3: Use IS_ENABLED(CONFIG_DEBUG_FS) to replace #ifdef DEBUG_FS.
v2: Remove a warning information
v1: Initial version.

Fixes: Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Reported-by: Massimo B. <massimo.b@gmx.net>
Reported-by: Kai Krakow <kai@kaishome.de>
Tested-by: Kai Krakow <kai@kaishome.de>
Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index 4e63c6f6c04d..d030ce3025a6 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c
@@ -250,7 +250,9 @@ void bch_debug_exit(void)
 
 int __init bch_debug_init(struct kobject *kobj)
 {
-	bcache_debug = debugfs_create_dir("bcache", NULL);
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
 
+	bcache_debug = debugfs_create_dir("bcache", NULL);
 	return IS_ERR_OR_NULL(bcache_debug);
 }

Re: FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

[Kai Krakow]

Hey Greg!

2018-05-20 9:49 GMT+02:00  <gregkh@linuxfoundation.org>:
>
> The patch below does not apply to the 4.16-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

The v1 version applied for me but it shows a compiler warning. I
didn't try the newer version yet.

I could prepare a back-ported version.

Regards,
Kai

> ------------------ original commit in Linus's tree ------------------
>
> From 1c1a2ee1b53b006754073eefc65d2b2cedb5264b Mon Sep 17 00:00:00 2001
> From: Coly Li <colyli@suse.de>
> Date: Thu, 17 May 2018 23:33:26 +0800
> Subject: [PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n
>
> Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
> returns the return value of debugfs_create_dir() to bcache_init(). When
> CONFIG_DEBUG_FS=n, bch_debug_init() always returns 1 and makes
> bcache_init() failedi.
>
> This patch makes bch_debug_init() always returns 0 if CONFIG_DEBUG_FS=n,
> so bcache can continue to work for the kernels which don't have debugfs
> enanbled.
>
> Changelog:
> v4: Add Acked-by from Kent Overstreet.
> v3: Use IS_ENABLED(CONFIG_DEBUG_FS) to replace #ifdef DEBUG_FS.
> v2: Remove a warning information
> v1: Initial version.
>
> Fixes: Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
> Cc: stable@vger.kernel.org
> Signed-off-by: Coly Li <colyli@suse.de>
> Reported-by: Massimo B. <massimo.b@gmx.net>
> Reported-by: Kai Krakow <kai@kaishome.de>
> Tested-by: Kai Krakow <kai@kaishome.de>
> Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>
> diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
> index 4e63c6f6c04d..d030ce3025a6 100644
> --- a/drivers/md/bcache/debug.c
> +++ b/drivers/md/bcache/debug.c
> @@ -250,7 +250,9 @@ void bch_debug_exit(void)
>
>  int __init bch_debug_init(struct kobject *kobj)
>  {
> -       bcache_debug = debugfs_create_dir("bcache", NULL);
> +       if (!IS_ENABLED(CONFIG_DEBUG_FS))
> +               return 0;
>
> +       bcache_debug = debugfs_create_dir("bcache", NULL);
>         return IS_ERR_OR_NULL(bcache_debug);
>  }
>

Re: FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

[Greg KH]

On Sun, May 20, 2018 at 10:59:32AM +0200, Kai Krakow wrote:
> Hey Greg!
> 
> The v1 version applied for me but it shows a compiler warning. I didn't try
> the newer version yet.
> 
> I could prepare a back-ported version.

Backported would be good.

Also, the code really is wrong even with this change.  No code path
should ever do anything different if debugfs is enabled or not, or based
on the return value of a debugfs call.  No need to check anything here
at all, the function should be:

void __init bch_debug_init(void)
{
	bcache_debug = debugfs_create_dir("bcache", NULL);
}

That's it, no checking, and all is fine and good.  Any result of a
debugfs call can always be fed back into another debugfs call with no
harm or errors happening.

thanks,

greg k-h

Re: FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

[Kai Krakow]

Hi Greg!

2018-05-20 11:04 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
> On Sun, May 20, 2018 at 10:59:32AM +0200, Kai Krakow wrote:
>> Hey Greg!
>>
>> The v1 version applied for me but it shows a compiler warning. I didn't try
>> the newer version yet.
>>
>> I could prepare a back-ported version.
>
> Backported would be good.

Currently on the way. I'm not much into kernel development so I can
only apply on 4.16.9, reboot, and check if it works. Hope that's okay.

How should it be tagged then? Should I add my "Signed-off-by" or another line?

Should it be sent as a v5 version of the patch?


> Also, the code really is wrong even with this change.  No code path
> should ever do anything different if debugfs is enabled or not, or based
> on the return value of a debugfs call.  No need to check anything here
> at all, the function should be:
>
> void __init bch_debug_init(void)
> {
>         bcache_debug = debugfs_create_dir("bcache", NULL);
> }
>
> That's it, no checking, and all is fine and good.  Any result of a
> debugfs call can always be fed back into another debugfs call with no
> harm or errors happening.

I'll try to figure out if this works, and only then send the patch.

Regards,
Kai

Re: FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

[Coly Li]

On 2018/5/20 5:14 PM, Kai Krakow wrote:
> Hi Greg!
> 
> 2018-05-20 11:04 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
>> On Sun, May 20, 2018 at 10:59:32AM +0200, Kai Krakow wrote:
>>> Hey Greg!
>>>
>>> The v1 version applied for me but it shows a compiler warning. I didn't try
>>> the newer version yet.
>>>
>>> I could prepare a back-ported version.
>>
>> Backported would be good.
> 
> Currently on the way. I'm not much into kernel development so I can
> only apply on 4.16.9, reboot, and check if it works. Hope that's okay.
> 
> How should it be tagged then? Should I add my "Signed-off-by" or another line?
> 
> Should it be sent as a v5 version of the patch?
> 
> 

Hi Kai,

I planed to back port the patch for stable after v4 patch merged into
mainline, and good to know this patch is merged into upstream today.

So the simplest way should be back port commit 1c1a2ee1b53b ("bcache:
return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n") for v4.16 stable tree.

If you are working on the back port, then I will step back. Thank you
for the quick response, very helpful :-)

Coly Li

>> Also, the code really is wrong even with this change.  No code path
>> should ever do anything different if debugfs is enabled or not, or based
>> on the return value of a debugfs call.  No need to check anything here
>> at all, the function should be:
>>
>> void __init bch_debug_init(void)
>> {
>>         bcache_debug = debugfs_create_dir("bcache", NULL);
>> }
>>
>> That's it, no checking, and all is fine and good.  Any result of a
>> debugfs call can always be fed back into another debugfs call with no
>> harm or errors happening.
> 
> I'll try to figure out if this works, and only then send the patch.
> 
> Regards,
> Kai
> 

Re: FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

[Kai Krakow]

Hello Coly, Greg!

2018-05-20 11:38 GMT+02:00 Coly Li <colyli@suse.de>:
> On 2018/5/20 5:14 PM, Kai Krakow wrote:
>> Hi Greg!
>>
>> 2018-05-20 11:04 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
>>> On Sun, May 20, 2018 at 10:59:32AM +0200, Kai Krakow wrote:
>>>> Hey Greg!
>>>>
>>>> The v1 version applied for me but it shows a compiler warning. I didn't try
>>>> the newer version yet.
>>>>
>>>> I could prepare a back-ported version.
>>>
>>> Backported would be good.
>>
>> Currently on the way. I'm not much into kernel development so I can
>> only apply on 4.16.9, reboot, and check if it works. Hope that's okay.
>>
>> How should it be tagged then? Should I add my "Signed-off-by" or another line?
>>
>> Should it be sent as a v5 version of the patch?
>>
>>
>
> Hi Kai,
>
> I planed to back port the patch for stable after v4 patch merged into
> mainline, and good to know this patch is merged into upstream today.
>
> So the simplest way should be back port commit 1c1a2ee1b53b ("bcache:
> return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n") for v4.16 stable tree.

I already did "git cherry-pick" as Greg suggested (with the id of the
failed patch).


> If you are working on the back port, then I will step back. Thank you
> for the quick response, very helpful :-)

Coly, then I could need your review after sending the patch.


>>> Also, the code really is wrong even with this change.  No code path
>>> should ever do anything different if debugfs is enabled or not, or based
>>> on the return value of a debugfs call.  No need to check anything here
>>> at all, the function should be:
>>>
>>> void __init bch_debug_init(void)
>>> {
>>>         bcache_debug = debugfs_create_dir("bcache", NULL);
>>> }
>>>
>>> That's it, no checking, and all is fine and good.  Any result of a
>>> debugfs call can always be fed back into another debugfs call with no
>>> harm or errors happening.
>>
>> I'll try to figure out if this works, and only then send the patch.

Thanks,
Kai

Re: FAILED: patch "[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n" failed to apply to 4.16-stable tree

[Greg KH]

On Sun, May 20, 2018 at 11:14:12AM +0200, Kai Krakow wrote:
> Hi Greg!
> 
> 2018-05-20 11:04 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
> > On Sun, May 20, 2018 at 10:59:32AM +0200, Kai Krakow wrote:
> >> Hey Greg!
> >>
> >> The v1 version applied for me but it shows a compiler warning. I didn't try
> >> the newer version yet.
> >>
> >> I could prepare a back-ported version.
> >
> > Backported would be good.
> 
> Currently on the way. I'm not much into kernel development so I can
> only apply on 4.16.9, reboot, and check if it works. Hope that's okay.
> 
> How should it be tagged then? Should I add my "Signed-off-by" or another line?

Just like a "normal" patch, yes, signed-off-by is fine.  If you do 'git
cherry-pick -x -s' it will put the correct information in there.

thanks,

greg k-h

[PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n

[Kai Krakow]

From: Coly Li <colyli@suse.de>

Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
returns the return value of debugfs_create_dir() to bcache_init(). When
CONFIG_DEBUG_FS=n, bch_debug_init() always returns 1 and makes
bcache_init() failedi.

This patch makes bch_debug_init() always returns 0 if CONFIG_DEBUG_FS=n,
so bcache can continue to work for the kernels which don't have debugfs
enanbled.

Changelog:
v4: Add Acked-by from Kent Overstreet.
v3: Use IS_ENABLED(CONFIG_DEBUG_FS) to replace #ifdef DEBUG_FS.
v2: Remove a warning information
v1: Initial version.

Fixes: Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Reported-by: Massimo B. <massimo.b@gmx.net>
Reported-by: Kai Krakow <kai@kaishome.de>
Tested-by: Kai Krakow <kai@kaishome.de>
Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 1c1a2ee1b53b006754073eefc65d2b2cedb5264b)
Signed-off-by: Kai Krakow <kai@kaishome.de>
---
 drivers/md/bcache/debug.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index af89408befe8..b218426a6493 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c
@@ -251,6 +251,9 @@ void bch_debug_exit(void)
 
 int __init bch_debug_init(struct kobject *kobj)
 {
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
+
 	debug = debugfs_create_dir("bcache", NULL);
 
 	return IS_ERR_OR_NULL(debug);
-- 
2.16.1

Re: [PATCH] bcache: return 0 from bch_debug_init() if CONFIG_DEBUG_FS=n

[Coly Li]

On 2018/5/20 5:53 PM, Kai Krakow wrote:
> From: Coly Li <colyli@suse.de>
> 
> Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
> returns the return value of debugfs_create_dir() to bcache_init(). When
> CONFIG_DEBUG_FS=n, bch_debug_init() always returns 1 and makes
> bcache_init() failedi.
> 
> This patch makes bch_debug_init() always returns 0 if CONFIG_DEBUG_FS=n,
> so bcache can continue to work for the kernels which don't have debugfs
> enanbled.
> 
> Changelog:
> v4: Add Acked-by from Kent Overstreet.
> v3: Use IS_ENABLED(CONFIG_DEBUG_FS) to replace #ifdef DEBUG_FS.
> v2: Remove a warning information
> v1: Initial version.
> 
> Fixes: Commit 539d39eb2708 ("bcache: fix wrong return value in bch_debug_init()")
> Cc: stable@vger.kernel.org
> Signed-off-by: Coly Li <colyli@suse.de>
> Reported-by: Massimo B. <massimo.b@gmx.net>
> Reported-by: Kai Krakow <kai@kaishome.de>
> Tested-by: Kai Krakow <kai@kaishome.de>
> Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> (cherry picked from commit 1c1a2ee1b53b006754073eefc65d2b2cedb5264b)
> Signed-off-by: Kai Krakow <kai@kaishome.de>

Reviewed-by: Coly Li <colyli@suse.de>

Thanks for the back port.

Coly Li

> ---
>  drivers/md/bcache/debug.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
> index af89408befe8..b218426a6493 100644
> --- a/drivers/md/bcache/debug.c
> +++ b/drivers/md/bcache/debug.c
> @@ -251,6 +251,9 @@ void bch_debug_exit(void)
>  
>  int __init bch_debug_init(struct kobject *kobj)
>  {
> +	if (!IS_ENABLED(CONFIG_DEBUG_FS))
> +		return 0;
> +
>  	debug = debugfs_create_dir("bcache", NULL);
>  
>  	return IS_ERR_OR_NULL(debug);
>