On 5/17/21 3:11 AM, Ingo Molnar wrote:

* Randy Dunlap [off-list ref] wrote:

quoted

Both arch/um/ and arch/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.

Fixes this kconfig warning: (for both um and 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]

Signed-off-by: Randy Dunlap <redacted>
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 <redacted>
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 <redacted>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: linux-um@lists.infradead.org
---
  lib/Kconfig.debug |    2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-next-20210514.orig/lib/Kconfig.debug
+++ linux-next-20210514/lib/Kconfig.debug

@@ -1383,7 +1383,7 @@ config LOCKDEP
  	bool
  	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
  	select STACKTRACE
-	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
+	depends on FRAME_POINTER || LOCKDEP_SUPPORT

Ok - the FRAME_POINTER bit is weird. Are there any architectures that have
FRAME_POINTER defined but no LOCKDEP_SUPPORT?

LOCK_DEBUGGING_SUPPORT depends on LOCKDEP_SUPPORT. So this patch is 
equivalent to just delete the second depends-on line. Beside LOCKDEP, 
LATENCYTOP also have exactly the same depends-on line.

So isn't FRAME_POINTER used mainly to support STACK_TRACE? However, 
LOCK_DEBUGGING_SUPPORT has already included STACK_TRACE_SUPPORT in its 
dependency. So why there is a FRAME_POINTER dependency?

Cheers,
Longman


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