[Linux-Xtensa] [PATCH 2/2] xtensa: use generic spinlock/rwlock implementation

Max Filippov jcmvbkbc at gmail.com
Thu Feb 7 20:23:24 UTC 2019


Drop custom spinlock/rwlock code and use ones from asm-generic. This way
there is less code duplication (atomic primitives are reused).

Signed-off-by: Max Filippov <jcmvbkbc at gmail.com>
---
 arch/xtensa/Kconfig                      |   2 +
 arch/xtensa/include/asm/Kbuild           |   2 +
 arch/xtensa/include/asm/spinlock.h       | 185 +------------------------------
 arch/xtensa/include/asm/spinlock_types.h |  15 +--
 4 files changed, 10 insertions(+), 194 deletions(-)

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index ce91682770cb..91a96cb958d8 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -4,6 +4,8 @@ config XTENSA
 	select ARCH_HAS_SYNC_DMA_FOR_CPU
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
 	select ARCH_NO_COHERENT_DMA_MMAP if !MMU
+	select ARCH_USE_QUEUED_RWLOCKS
+	select ARCH_USE_QUEUED_SPINLOCKS
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select BUILDTIME_EXTABLE_SORT
diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild
index e255683cd520..27bd3d33b010 100644
--- a/arch/xtensa/include/asm/Kbuild
+++ b/arch/xtensa/include/asm/Kbuild
@@ -23,6 +23,8 @@ generic-y += mm-arch-hooks.h
 generic-y += param.h
 generic-y += percpu.h
 generic-y += preempt.h
+generic-y += qrwlock.h
+generic-y += qspinlock.h
 generic-y += rwsem.h
 generic-y += sections.h
 generic-y += topology.h
diff --git a/arch/xtensa/include/asm/spinlock.h b/arch/xtensa/include/asm/spinlock.h
index c6e1290dcbb7..584b0de6f2ca 100644
--- a/arch/xtensa/include/asm/spinlock.h
+++ b/arch/xtensa/include/asm/spinlock.h
@@ -12,188 +12,9 @@
 #define _XTENSA_SPINLOCK_H
 
 #include <asm/barrier.h>
-#include <asm/processor.h>
+#include <asm/qrwlock.h>
+#include <asm/qspinlock.h>
 
-/*
- * spinlock
- *
- * There is at most one owner of a spinlock.  There are not different
- * types of spinlock owners like there are for rwlocks (see below).
- *
- * When trying to obtain a spinlock, the function "spins" forever, or busy-
- * waits, until the lock is obtained.  When spinning, presumably some other
- * owner will soon give up the spinlock making it available to others.  Use
- * the trylock functions to avoid spinning forever.
- *
- * possible values:
- *
- *    0         nobody owns the spinlock
- *    1         somebody owns the spinlock
- */
-
-#define arch_spin_is_locked(x) ((x)->slock != 0)
-
-static inline void arch_spin_lock(arch_spinlock_t *lock)
-{
-	unsigned long tmp;
-
-	__asm__ __volatile__(
-			"       movi    %0, 0\n"
-			"       wsr     %0, scompare1\n"
-			"1:     movi    %0, 1\n"
-			"       s32c1i  %0, %1, 0\n"
-			"       bnez    %0, 1b\n"
-			: "=&a" (tmp)
-			: "a" (&lock->slock)
-			: "memory");
-}
-
-/* Returns 1 if the lock is obtained, 0 otherwise. */
-
-static inline int arch_spin_trylock(arch_spinlock_t *lock)
-{
-	unsigned long tmp;
-
-	__asm__ __volatile__(
-			"       movi    %0, 0\n"
-			"       wsr     %0, scompare1\n"
-			"       movi    %0, 1\n"
-			"       s32c1i  %0, %1, 0\n"
-			: "=&a" (tmp)
-			: "a" (&lock->slock)
-			: "memory");
-
-	return tmp == 0 ? 1 : 0;
-}
-
-static inline void arch_spin_unlock(arch_spinlock_t *lock)
-{
-	unsigned long tmp;
-
-	__asm__ __volatile__(
-			"       movi    %0, 0\n"
-			"       s32ri   %0, %1, 0\n"
-			: "=&a" (tmp)
-			: "a" (&lock->slock)
-			: "memory");
-}
-
-/*
- * rwlock
- *
- * Read-write locks are really a more flexible spinlock.  They allow
- * multiple readers but only one writer.  Write ownership is exclusive
- * (i.e., all other readers and writers are blocked from ownership while
- * there is a write owner).  These rwlocks are unfair to writers.  Writers
- * can be starved for an indefinite time by readers.
- *
- * possible values:
- *
- *   0          nobody owns the rwlock
- *  >0          one or more readers own the rwlock
- *                (the positive value is the actual number of readers)
- *  0x80000000  one writer owns the rwlock, no other writers, no readers
- */
-
-static inline void arch_write_lock(arch_rwlock_t *rw)
-{
-	unsigned long tmp;
-
-	__asm__ __volatile__(
-			"       movi    %0, 0\n"
-			"       wsr     %0, scompare1\n"
-			"1:     movi    %0, 1\n"
-			"       slli    %0, %0, 31\n"
-			"       s32c1i  %0, %1, 0\n"
-			"       bnez    %0, 1b\n"
-			: "=&a" (tmp)
-			: "a" (&rw->lock)
-			: "memory");
-}
-
-/* Returns 1 if the lock is obtained, 0 otherwise. */
-
-static inline int arch_write_trylock(arch_rwlock_t *rw)
-{
-	unsigned long tmp;
-
-	__asm__ __volatile__(
-			"       movi    %0, 0\n"
-			"       wsr     %0, scompare1\n"
-			"       movi    %0, 1\n"
-			"       slli    %0, %0, 31\n"
-			"       s32c1i  %0, %1, 0\n"
-			: "=&a" (tmp)
-			: "a" (&rw->lock)
-			: "memory");
-
-	return tmp == 0 ? 1 : 0;
-}
-
-static inline void arch_write_unlock(arch_rwlock_t *rw)
-{
-	unsigned long tmp;
-
-	__asm__ __volatile__(
-			"       movi    %0, 0\n"
-			"       s32ri   %0, %1, 0\n"
-			: "=&a" (tmp)
-			: "a" (&rw->lock)
-			: "memory");
-}
-
-static inline void arch_read_lock(arch_rwlock_t *rw)
-{
-	unsigned long tmp;
-	unsigned long result;
-
-	__asm__ __volatile__(
-			"1:     l32i    %1, %2, 0\n"
-			"       bltz    %1, 1b\n"
-			"       wsr     %1, scompare1\n"
-			"       addi    %0, %1, 1\n"
-			"       s32c1i  %0, %2, 0\n"
-			"       bne     %0, %1, 1b\n"
-			: "=&a" (result), "=&a" (tmp)
-			: "a" (&rw->lock)
-			: "memory");
-}
-
-/* Returns 1 if the lock is obtained, 0 otherwise. */
-
-static inline int arch_read_trylock(arch_rwlock_t *rw)
-{
-	unsigned long result;
-	unsigned long tmp;
-
-	__asm__ __volatile__(
-			"       l32i    %1, %2, 0\n"
-			"       addi    %0, %1, 1\n"
-			"       bltz    %0, 1f\n"
-			"       wsr     %1, scompare1\n"
-			"       s32c1i  %0, %2, 0\n"
-			"       sub     %0, %0, %1\n"
-			"1:\n"
-			: "=&a" (result), "=&a" (tmp)
-			: "a" (&rw->lock)
-			: "memory");
-
-	return result == 0;
-}
-
-static inline void arch_read_unlock(arch_rwlock_t *rw)
-{
-	unsigned long tmp1, tmp2;
-
-	__asm__ __volatile__(
-			"1:     l32i    %1, %2, 0\n"
-			"       addi    %0, %1, -1\n"
-			"       wsr     %1, scompare1\n"
-			"       s32c1i  %0, %2, 0\n"
-			"       bne     %0, %1, 1b\n"
-			: "=&a" (tmp1), "=&a" (tmp2)
-			: "a" (&rw->lock)
-			: "memory");
-}
+#define smp_mb__after_spinlock()	smp_mb()
 
 #endif	/* _XTENSA_SPINLOCK_H */
diff --git a/arch/xtensa/include/asm/spinlock_types.h b/arch/xtensa/include/asm/spinlock_types.h
index bb1fe6c1816e..64c9389254f1 100644
--- a/arch/xtensa/include/asm/spinlock_types.h
+++ b/arch/xtensa/include/asm/spinlock_types.h
@@ -2,20 +2,11 @@
 #ifndef __ASM_SPINLOCK_TYPES_H
 #define __ASM_SPINLOCK_TYPES_H
 
-#ifndef __LINUX_SPINLOCK_TYPES_H
+#if !defined(__LINUX_SPINLOCK_TYPES_H) && !defined(__ASM_SPINLOCK_H)
 # error "please don't include this file directly"
 #endif
 
-typedef struct {
-	volatile unsigned int slock;
-} arch_spinlock_t;
-
-#define __ARCH_SPIN_LOCK_UNLOCKED	{ 0 }
-
-typedef struct {
-	volatile unsigned int lock;
-} arch_rwlock_t;
-
-#define __ARCH_RW_LOCK_UNLOCKED		{ 0 }
+#include <asm-generic/qspinlock_types.h>
+#include <asm-generic/qrwlock_types.h>
 
 #endif
-- 
2.11.0



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