[BUG] new MIPS compile error on v5.15.27

[BUG] new MIPS compile error on v5.15.27

[H. Nikolaus Schaller]

upstream commit 277c8cb3e8ac ("MIPS: fix local_{add,sub}_return on MIPS64")

was backported to v5.15.27 as

commit f98371d2ac83 ("MIPS: fix local_{add,sub}_return on MIPS64")

but breaks MIPS build:

In file included from ./arch/mips/include/asm/local.h:8:0,
                 from ./include/linux/genhd.h:20,
                 from ./include/linux/blkdev.h:8,
                 from ./include/linux/blk-cgroup.h:23,
                 from ./include/linux/writeback.h:14,
                 from ./include/linux/memcontrol.h:22,
                 from ./include/net/sock.h:53,
                 from ./include/linux/tcp.h:19,
                 from drivers/net/slip/slip.c:91:
./arch/mips/include/asm/asm.h:68:0: warning: "END" redefined
 #define END(function)     \
 
In file included from drivers/net/slip/slip.c:88:0:
drivers/net/slip/slip.h:44:0: note: this is the location of the previous definition
 #define END             0300  /* indicates end of frame */

Analyses reveals that with the backported MIPS fix there is a new
#include <asm/asm.h> introduced by ./arch/mips/include/asm/local.h
which already defines some END macro.

But why does v5.16.x compile fine where

commit a0ecfd10d669c ("MIPS: fix local_{add,sub}_return on MIPS64")

is also present since v5.16.3?

Deeper analyses shows that there is another patch introduced
in v5.16-rc1 which removed one #include in the above chain and
therefore does not define END by asm/asm.h:

commit 348332e000697 ("mm: don't include <linux/blk-cgroup.h> in <linux/writeback.h>")

Hence, the MIPS fix should only be applied to branches where
the mm fix is already present. Or the mm fix should be backported
as well (if it has no side-effects).

Note: the MIPS fix was apparently not (yet?) applied to v5.10.y or earlier
even tough the Fixes: 7232311ef14c ("local_t: mips extension")
would be true.

BR and thanks,
Nikolaus Schaller

Re: [BUG] new MIPS compile error on v5.15.27

[Christoph Hellwig]

Please fix <asm/asm.h>.   The most trivial fix might be to only defined
END() under __ASSEMBLY__, although in the long run it probably wants a
better name as well.

Re: [BUG] new MIPS compile error on v5.15.27

[H. Nikolaus Schaller]

> Am 10.03.2022 um 17:28 schrieb Christoph Hellwig <hch@lst.de>:
> 
> Please fix <asm/asm.h>.   The most trivial fix might be to only defined
> END() under __ASSEMBLY__, although in the long run it probably wants a
> better name as well.

Well

a) the bug (name conflict) does not occur in v5.16 or later
b) I am in no way responsible for either of the patches or subsystems

So someone else has to either (partially?) backport

commit 348332e000697 ("mm: don't include <linux/blk-cgroup.h> in <linux/writeback.h>")

to 5.17.y

or write your proposed fix just for 5.17.y because it is not required elsewhere.

BR and thanks,
Nikolaus

Re: [BUG] new MIPS compile error on v5.15.27

[H. Nikolaus Schaller]

> Am 10.03.2022 um 17:34 schrieb H. Nikolaus Schaller <hns@goldelico.com>:
> 
> 
>> Am 10.03.2022 um 17:28 schrieb Christoph Hellwig <hch@lst.de>:
>> 
>> Please fix <asm/asm.h>.   The most trivial fix might be to only defined
>> END() under __ASSEMBLY__, although in the long run it probably wants a
>> better name as well.
> 
> Well
> 
> a) the bug (name conflict) does not occur in v5.16 or later
> b) I am in no way responsible for either of the patches or subsystems
> 
> So someone else has to either (partially?) backport
> 
> commit 348332e000697 ("mm: don't include <linux/blk-cgroup.h> in <linux/writeback.h>")
> 
> to 5.17.y
> 
> or write your proposed fix just for 5.17.y because it is not required elsewhere.

sorry, typo: just for v5.15.y

> 
> BR and thanks,
> Nikolaus
> 

Re: [BUG] new MIPS compile error on v5.15.27

[Maciej W. Rozycki]

On Thu, 10 Mar 2022, Christoph Hellwig wrote:

> Please fix <asm/asm.h>.   The most trivial fix might be to only defined
> END() under __ASSEMBLY__, although in the long run it probably wants a
> better name as well.

 FWIW the END macro has its roots in IRIX if not MIPSCO.  It's been around 
for some 30 years if not more.  MIPS/ULTRIX may have had it too, as it's 
originally all ECOFF stuff, i.e. `.end', `.ent', `.frame', etc. assembly 
pseudo-ops for symbol/debug information.

  Maciej

Re: [BUG] new MIPS compile error on v5.15.27

[Greg KH]

On Thu, Mar 10, 2022 at 05:25:07PM +0100, H. Nikolaus Schaller wrote:
> upstream commit 277c8cb3e8ac ("MIPS: fix local_{add,sub}_return on MIPS64")
> 
> was backported to v5.15.27 as
> 
> commit f98371d2ac83 ("MIPS: fix local_{add,sub}_return on MIPS64")
> 
> but breaks MIPS build:
> 
> In file included from ./arch/mips/include/asm/local.h:8:0,
>                  from ./include/linux/genhd.h:20,
>                  from ./include/linux/blkdev.h:8,
>                  from ./include/linux/blk-cgroup.h:23,
>                  from ./include/linux/writeback.h:14,
>                  from ./include/linux/memcontrol.h:22,
>                  from ./include/net/sock.h:53,
>                  from ./include/linux/tcp.h:19,
>                  from drivers/net/slip/slip.c:91:
> ./arch/mips/include/asm/asm.h:68:0: warning: "END" redefined
>  #define END(function)     \
>  
> In file included from drivers/net/slip/slip.c:88:0:
> drivers/net/slip/slip.h:44:0: note: this is the location of the previous definition
>  #define END             0300  /* indicates end of frame */
> 
> Analyses reveals that with the backported MIPS fix there is a new
> #include <asm/asm.h> introduced by ./arch/mips/include/asm/local.h
> which already defines some END macro.
> 
> But why does v5.16.x compile fine where
> 
> commit a0ecfd10d669c ("MIPS: fix local_{add,sub}_return on MIPS64")
> 
> is also present since v5.16.3?
> 
> Deeper analyses shows that there is another patch introduced
> in v5.16-rc1 which removed one #include in the above chain and
> therefore does not define END by asm/asm.h:
> 
> commit 348332e000697 ("mm: don't include <linux/blk-cgroup.h> in <linux/writeback.h>")
> 
> Hence, the MIPS fix should only be applied to branches where
> the mm fix is already present. Or the mm fix should be backported
> as well (if it has no side-effects).
> 
> Note: the MIPS fix was apparently not (yet?) applied to v5.10.y or earlier
> even tough the Fixes: 7232311ef14c ("local_t: mips extension")
> would be true.

Thanks for the report.  I'll work on resolving this for the next round
of stable releases _after_ the ones that are currently out for review
are released.

thanks,

greg k-h

Re: [BUG] new MIPS compile error on v5.15.27

[Christoph Hellwig]

On Thu, Mar 10, 2022 at 08:05:04PM +0100, Greg KH wrote:
> Thanks for the report.  I'll work on resolving this for the next round
> of stable releases _after_ the ones that are currently out for review
> are released.

If you think the genhd.h include cleanup is the best fix feel free
to pick it up.  But I really think it is just hiding the problem,
and that problem will resurface.