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* [PATCH] locking/arch: Move qrwlock.h include after qspinlock.h
@ 2021-02-10 18:33 Paolo Bonzini
  0 siblings, 0 replies; only message in thread
From: Paolo Bonzini @ 2021-02-10 18:33 UTC (permalink / raw)
  To: linux-kernel, kvm
  Cc: Guenter Roeck, Waiman Long, Ben Gardon, Peter Zijlstra,
	Ingo Molnar, Will Deacon, Catalin Marinas, Thomas Bogendoerfer,
	David S. Miller, Chris Zankel, Max Filippov, Arnd Bergmann,
	Guo Ren, Davidlohr Bueso,
	moderated list:ARM64 PORT (AARCH64 ARCHITECTURE),
	open list:MIPS, open list:SPARC + UltraSPARC (sparc/sparc64),
	open list:TENSILICA XTENSA PORT (xtensa),
	open list:GENERIC INCLUDE/ASM HEADER FILES,
	open list:C-SKY ARCHITECTURE

include/asm-generic/qrwlock.h was trying to get arch_spin_is_locked via
asm-generic/qspinlock.h.  However, this does not work because architectures
might be using queued rwlocks but not queued spinlocks (csky), or because they
might be defining their own queued_* macros before including asm/qspinlock.h.

To fix this, ensure that asm/spinlock.h always includes qrwlock.h after
defining arch_spin_is_locked (either directly for csky, or via
asm/qspinlock.h for other architectures).  The only inclusion elsewhere
is in kernel/locking/qrwlock.c.  That one is really unnecessary because
the file is only compiled in SMP configurations (config QUEUED_RWLOCKS
depends on SMP) and in that case linux/spinlock.h already includes
asm/qrwlock.h if needed, via asm/spinlock.h.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Waiman Long <longman@redhat.com>
Fixes: 26128cb6c7e6 ("locking/rwlocks: Add contention detection for rwlocks")
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
	v1->v2: Fix sparc too.  Add a comment in qrwlock.h itself.
	Remove unnecessary inclusion in kernel/locking/qrwlock.c

 arch/arm64/include/asm/spinlock.h    | 2 +-
 arch/mips/include/asm/spinlock.h     | 2 +-
 arch/sparc/include/asm/spinlock_64.h | 2 +-
 arch/xtensa/include/asm/spinlock.h   | 2 +-
 include/asm-generic/qrwlock.h        | 3 ++-
 kernel/locking/qrwlock.c             | 1 -
 6 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 9083d6992603..0525c0b089ed 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -5,8 +5,8 @@
 #ifndef __ASM_SPINLOCK_H
 #define __ASM_SPINLOCK_H
 
-#include <asm/qrwlock.h>
 #include <asm/qspinlock.h>
+#include <asm/qrwlock.h>
 
 /* See include/linux/spinlock.h */
 #define smp_mb__after_spinlock()	smp_mb()
diff --git a/arch/mips/include/asm/spinlock.h b/arch/mips/include/asm/spinlock.h
index 8a88eb265516..6ce2117e49f6 100644
--- a/arch/mips/include/asm/spinlock.h
+++ b/arch/mips/include/asm/spinlock.h
@@ -10,7 +10,6 @@
 #define _ASM_SPINLOCK_H
 
 #include <asm/processor.h>
-#include <asm/qrwlock.h>
 
 #include <asm-generic/qspinlock_types.h>
 
@@ -27,5 +26,6 @@ static inline void queued_spin_unlock(struct qspinlock *lock)
 }
 
 #include <asm/qspinlock.h>
+#include <asm/qrwlock.h>
 
 #endif /* _ASM_SPINLOCK_H */
diff --git a/arch/sparc/include/asm/spinlock_64.h b/arch/sparc/include/asm/spinlock_64.h
index 7fc82a233f49..3a9a0b0c7465 100644
--- a/arch/sparc/include/asm/spinlock_64.h
+++ b/arch/sparc/include/asm/spinlock_64.h
@@ -11,8 +11,8 @@
 
 #include <asm/processor.h>
 #include <asm/barrier.h>
-#include <asm/qrwlock.h>
 #include <asm/qspinlock.h>
+#include <asm/qrwlock.h>
 
 #endif /* !(__ASSEMBLY__) */
 
diff --git a/arch/xtensa/include/asm/spinlock.h b/arch/xtensa/include/asm/spinlock.h
index 584b0de6f2ca..41c449ece2d8 100644
--- a/arch/xtensa/include/asm/spinlock.h
+++ b/arch/xtensa/include/asm/spinlock.h
@@ -12,8 +12,8 @@
 #define _XTENSA_SPINLOCK_H
 
 #include <asm/barrier.h>
-#include <asm/qrwlock.h>
 #include <asm/qspinlock.h>
+#include <asm/qrwlock.h>
 
 #define smp_mb__after_spinlock()	smp_mb()
 
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
index 0020d3b820a7..7ae0ece07b4e 100644
--- a/include/asm-generic/qrwlock.h
+++ b/include/asm-generic/qrwlock.h
@@ -14,7 +14,8 @@
 #include <asm/processor.h>
 
 #include <asm-generic/qrwlock_types.h>
-#include <asm-generic/qspinlock.h>
+
+/* Must be included from asm/spinlock.h after defining arch_spin_is_locked.  */
 
 /*
  * Writer states & reader shift and bias.
diff --git a/kernel/locking/qrwlock.c b/kernel/locking/qrwlock.c
index fe9ca92faa2a..4786dd271b45 100644
--- a/kernel/locking/qrwlock.c
+++ b/kernel/locking/qrwlock.c
@@ -12,7 +12,6 @@
 #include <linux/percpu.h>
 #include <linux/hardirq.h>
 #include <linux/spinlock.h>
-#include <asm/qrwlock.h>
 
 /**
  * queued_read_lock_slowpath - acquire read lock of a queue rwlock
-- 
2.26.2


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2021-02-10 18:33 [PATCH] locking/arch: Move qrwlock.h include after qspinlock.h Paolo Bonzini

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