diff mbox series

[v2] LOCKDEP: reduce LOCKDEP dependency list

Message ID 20210524224150.8009-1-rdunlap@infradead.org
State Not Applicable
Headers show
Series [v2] LOCKDEP: reduce LOCKDEP dependency list | expand

Commit Message

Randy Dunlap May 24, 2021, 10:41 p.m. UTC
Some arches (um, sparc64, riscv, xtensa) cause a Kconfig warning for
LOCKDEP.
These arch-es select LOCKDEP_SUPPORT but they are not listed as one
of the arch-es that LOCKDEP depends on.

Since (16) arch-es define the Kconfig symbol LOCKDEP_SUPPORT if they
intend to have LOCKDEP support, replace the awkward list of
arch-es that LOCKDEP depends on with the LOCKDEP_SUPPORT symbol.

But wait. LOCKDEP_SUPPORT is included in LOCK_DEBUGGING_SUPPORT,
which is already a dependency here, so LOCKDEP_SUPPORT is redundant
and not needed.
That leaves the FRAME_POINTER dependency, but it is part of an
expression like this:
	depends on (A && B) && (FRAME_POINTER || B')
where B' is a dependency of B so if B is true then B' is true
and the value of FRAME_POINTER does not matter.
Thus we can also delete the FRAME_POINTER dependency.

Fixes this kconfig warning: (for um, sparc64, riscv, xtensa)

WARNING: unmet direct dependencies detected for LOCKDEP
  Depends on [n]: DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y] && (FRAME_POINTER [=n] || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86)
  Selected by [y]:
  - PROVE_LOCKING [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
  - LOCK_STAT [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
  - DEBUG_LOCK_ALLOC [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]

Link to v1: https://lore.kernel.org/lkml/20210517034430.9569-1-rdunlap@infradead.org/

Fixes: 7d37cb2c912d ("lib: fix kconfig dependency on ARCH_WANT_FRAME_POINTERS")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-xtensa@linux-xtensa.org
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: linux-um@lists.infradead.org
Cc: Julian Braha <julianbraha@gmail.com>
Cc: linux-arch@vger.kernel.org
---
@Julian: please take a look. I'm a little concerned about the
  FRAME_POINTER dependency going away when our 2 patches are combined.

v2: drop depends on LOCKDEP_SUPPORT for LOCKDEP; the use of
    LOCK_DEBUGGING_SUPPORT already covers that dependency;
    drop FRAME_POINTER dependency (thanks to Waiman Long
    for both of these suggestions)
v2: add CC: to linux-arch

 lib/Kconfig.debug |    1 -
 1 file changed, 1 deletion(-)

Comments

Peter Zijlstra May 25, 2021, 7:07 a.m. UTC | #1
On Mon, May 24, 2021 at 03:41:50PM -0700, Randy Dunlap wrote:
> Some arches (um, sparc64, riscv, xtensa) cause a Kconfig warning for
> LOCKDEP.
> These arch-es select LOCKDEP_SUPPORT but they are not listed as one
> of the arch-es that LOCKDEP depends on.
> 
> Since (16) arch-es define the Kconfig symbol LOCKDEP_SUPPORT if they
> intend to have LOCKDEP support, replace the awkward list of
> arch-es that LOCKDEP depends on with the LOCKDEP_SUPPORT symbol.
> 
> But wait. LOCKDEP_SUPPORT is included in LOCK_DEBUGGING_SUPPORT,
> which is already a dependency here, so LOCKDEP_SUPPORT is redundant
> and not needed.
> That leaves the FRAME_POINTER dependency, but it is part of an
> expression like this:
> 	depends on (A && B) && (FRAME_POINTER || B')
> where B' is a dependency of B so if B is true then B' is true
> and the value of FRAME_POINTER does not matter.
> Thus we can also delete the FRAME_POINTER dependency.
> 
> Fixes this kconfig warning: (for um, sparc64, riscv, xtensa)
> 
> WARNING: unmet direct dependencies detected for LOCKDEP
>   Depends on [n]: DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y] && (FRAME_POINTER [=n] || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86)
>   Selected by [y]:
>   - PROVE_LOCKING [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
>   - LOCK_STAT [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
>   - DEBUG_LOCK_ALLOC [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
> 
> Link to v1: https://lore.kernel.org/lkml/20210517034430.9569-1-rdunlap@infradead.org/
> 
> Fixes: 7d37cb2c912d ("lib: fix kconfig dependency on ARCH_WANT_FRAME_POINTERS")
> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>

Thanks!
Peter Zijlstra May 25, 2021, 7:08 a.m. UTC | #2
On Mon, May 24, 2021 at 11:31:22PM -0400, Julian Braha wrote:
> Hi Randy,
> 
> It seems I introduced a new unmet dependency bug
> in my attempt to fix one :/
> 
> Anyway, I don't see why the dependency on FRAME_POINTER
> was necessary in the first place, so LGTM.

It might have been an attempt at ensuring sane backtraces; but I didn't
dig into the history of the thing. Either way around, it's fairly
out-dated if that was indeed the case.
Waiman Long May 25, 2021, 2:17 p.m. UTC | #3
On 5/24/21 6:41 PM, Randy Dunlap wrote:
> Some arches (um, sparc64, riscv, xtensa) cause a Kconfig warning for
> LOCKDEP.
> These arch-es select LOCKDEP_SUPPORT but they are not listed as one
> of the arch-es that LOCKDEP depends on.
>
> Since (16) arch-es define the Kconfig symbol LOCKDEP_SUPPORT if they
> intend to have LOCKDEP support, replace the awkward list of
> arch-es that LOCKDEP depends on with the LOCKDEP_SUPPORT symbol.
>
> But wait. LOCKDEP_SUPPORT is included in LOCK_DEBUGGING_SUPPORT,
> which is already a dependency here, so LOCKDEP_SUPPORT is redundant
> and not needed.
> That leaves the FRAME_POINTER dependency, but it is part of an
> expression like this:
> 	depends on (A && B) && (FRAME_POINTER || B')
> where B' is a dependency of B so if B is true then B' is true
> and the value of FRAME_POINTER does not matter.
> Thus we can also delete the FRAME_POINTER dependency.
>
> Fixes this kconfig warning: (for um, sparc64, riscv, xtensa)
>
> WARNING: unmet direct dependencies detected for LOCKDEP
>    Depends on [n]: DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y] && (FRAME_POINTER [=n] || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86)
>    Selected by [y]:
>    - PROVE_LOCKING [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
>    - LOCK_STAT [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
>    - DEBUG_LOCK_ALLOC [=y] && DEBUG_KERNEL [=y] && LOCK_DEBUGGING_SUPPORT [=y]
>
> Link to v1: https://lore.kernel.org/lkml/20210517034430.9569-1-rdunlap@infradead.org/
>
> Fixes: 7d37cb2c912d ("lib: fix kconfig dependency on ARCH_WANT_FRAME_POINTERS")
> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Waiman Long <longman@redhat.com>
> Cc: Boqun Feng <boqun.feng@gmail.com>
> Cc: Chris Zankel <chris@zankel.net>
> Cc: Max Filippov <jcmvbkbc@gmail.com>
> Cc: linux-xtensa@linux-xtensa.org
> Cc: Johannes Berg <johannes@sipsolutions.net>
> Cc: Jeff Dike <jdike@addtoit.com>
> Cc: Richard Weinberger <richard@nod.at>
> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
> Cc: linux-um@lists.infradead.org
> Cc: Julian Braha <julianbraha@gmail.com>
> Cc: linux-arch@vger.kernel.org
> ---
> @Julian: please take a look. I'm a little concerned about the
>    FRAME_POINTER dependency going away when our 2 patches are combined.
>
> v2: drop depends on LOCKDEP_SUPPORT for LOCKDEP; the use of
>      LOCK_DEBUGGING_SUPPORT already covers that dependency;
>      drop FRAME_POINTER dependency (thanks to Waiman Long
>      for both of these suggestions)
> v2: add CC: to linux-arch
>
>   lib/Kconfig.debug |    1 -
>   1 file changed, 1 deletion(-)
>
> --- linux-next-20210524.orig/lib/Kconfig.debug
> +++ linux-next-20210524/lib/Kconfig.debug
> @@ -1383,7 +1383,6 @@ config LOCKDEP
>   	bool
>   	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
>   	select STACKTRACE
> -	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
>   	select KALLSYMS
>   	select KALLSYMS_ALL
>   
>
Acked-by: Waiman Long <longman@redhat.com>

Cheers,
Longman
diff mbox series

Patch

--- linux-next-20210524.orig/lib/Kconfig.debug
+++ linux-next-20210524/lib/Kconfig.debug
@@ -1383,7 +1383,6 @@  config LOCKDEP
 	bool
 	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
 	select STACKTRACE
-	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
 	select KALLSYMS
 	select KALLSYMS_ALL