arch/sparc: Enable queued spinlock support for SPARC

This patch makes the necessary changes in SPARC architecture to enable
queued spinlock support. Here are some of the earlier discussions about
this feature.
https://lwn.net/Articles/561775/
https://lwn.net/Articles/590243/

Cleaned-up the spinlock_64.h. The definitions of arch_spin_xxx are
replaced by the function in <asm-generic/qspinlock.h>

Signed-off-by: Babu Moger <babu.moger@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 0e80652075961afa99d155b214a0f9c9db5c9b97..78af684f63b94065288b2a2efbbd0151beac4d73 100644 (file)
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -84,6 +84,7 @@ config SPARC64
        select HAVE_NMI
        select HAVE_REGS_AND_STACK_ACCESS_API
        select ARCH_USE_QUEUED_RWLOCKS
+       select ARCH_USE_QUEUED_SPINLOCKS
 
 config ARCH_DEFCONFIG
        string

diff --git a/arch/sparc/include/asm/qspinlock.h b/arch/sparc/include/asm/qspinlock.h
new file mode 100644 (file)
index 0000000..5ae9a28
--- /dev/null
+++ b/arch/sparc/include/asm/qspinlock.h
@@ -0,0 +1,7 @@
+#ifndef _ASM_SPARC_QSPINLOCK_H
+#define _ASM_SPARC_QSPINLOCK_H
+
+#include <asm-generic/qspinlock_types.h>
+#include <asm-generic/qspinlock.h>
+
+#endif /* _ASM_SPARC_QSPINLOCK_H */

diff --git a/arch/sparc/include/asm/spinlock_64.h b/arch/sparc/include/asm/spinlock_64.h
index 8901c2d4ada9aae37985aea085126c365cc734e5..f7028f5e1a5a3bff399a7a02aa4655f7cad8e012 100644 (file)
--- a/arch/sparc/include/asm/spinlock_64.h
+++ b/arch/sparc/include/asm/spinlock_64.h
@@ -11,89 +11,7 @@
 #include <asm/processor.h>
 #include <asm/barrier.h>
 #include <asm/qrwlock.h>
-
-/* To get debugging spinlocks which detect and catch
- * deadlock situations, set CONFIG_DEBUG_SPINLOCK
- * and rebuild your kernel.
- */
-
-/* Because we play games to save cycles in the non-contention case, we
- * need to be extra careful about branch targets into the "spinning"
- * code.  They live in their own section, but the newer V9 branches
- * have a shorter range than the traditional 32-bit sparc branch
- * variants.  The rule is that the branches that go into and out of
- * the spinner sections must be pre-V9 branches.
- */
-
-#define arch_spin_is_locked(lp)        ((lp)->lock != 0)
-
-static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
-{
-       smp_cond_load_acquire(&lock->lock, !VAL);
-}
-
-static inline void arch_spin_lock(arch_spinlock_t *lock)
-{
-       unsigned long tmp;
-
-       __asm__ __volatile__(
-"1:    ldstub          [%1], %0\n"
-"      brnz,pn         %0, 2f\n"
-"       nop\n"
-"      .subsection     2\n"
-"2:    ldub            [%1], %0\n"
-"      brnz,pt         %0, 2b\n"
-"       nop\n"
-"      ba,a,pt         %%xcc, 1b\n"
-"      .previous"
-       : "=&r" (tmp)
-       : "r" (lock)
-       : "memory");
-}
-
-static inline int arch_spin_trylock(arch_spinlock_t *lock)
-{
-       unsigned long result;
-
-       __asm__ __volatile__(
-"      ldstub          [%1], %0\n"
-       : "=r" (result)
-       : "r" (lock)
-       : "memory");
-
-       return (result == 0UL);
-}
-
-static inline void arch_spin_unlock(arch_spinlock_t *lock)
-{
-       __asm__ __volatile__(
-"      stb             %%g0, [%0]"
-       : /* No outputs */
-       : "r" (lock)
-       : "memory");
-}
-
-static inline void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
-{
-       unsigned long tmp1, tmp2;
-
-       __asm__ __volatile__(
-"1:    ldstub          [%2], %0\n"
-"      brnz,pn         %0, 2f\n"
-"       nop\n"
-"      .subsection     2\n"
-"2:    rdpr            %%pil, %1\n"
-"      wrpr            %3, %%pil\n"
-"3:    ldub            [%2], %0\n"
-"      brnz,pt         %0, 3b\n"
-"       nop\n"
-"      ba,pt           %%xcc, 1b\n"
-"       wrpr           %1, %%pil\n"
-"      .previous"
-       : "=&r" (tmp1), "=&r" (tmp2)
-       : "r"(lock), "r"(flags)
-       : "memory");
-}
+#include <asm/qspinlock.h>
 
 #define arch_read_lock_flags(p, f) arch_read_lock(p)
 #define arch_write_lock_flags(p, f) arch_write_lock(p)

diff --git a/arch/sparc/include/asm/spinlock_types.h b/arch/sparc/include/asm/spinlock_types.h
index 64fce21b23df48e651a7666aefac9b2dd8182089..bce8ef44dfa99bce688e936c8c9d74c0c215b3e6 100644 (file)
--- a/arch/sparc/include/asm/spinlock_types.h
+++ b/arch/sparc/include/asm/spinlock_types.h
@@ -1,11 +1,16 @@
 #ifndef __SPARC_SPINLOCK_TYPES_H
 #define __SPARC_SPINLOCK_TYPES_H
 
+#ifdef CONFIG_QUEUED_SPINLOCKS
+#include <asm-generic/qspinlock_types.h>
+#else
+
 typedef struct {
        volatile unsigned char lock;
 } arch_spinlock_t;
 
 #define __ARCH_SPIN_LOCK_UNLOCKED      { 0 }
+#endif /* CONFIG_QUEUED_SPINLOCKS */
 
 #ifdef CONFIG_QUEUED_RWLOCKS
 #include <asm-generic/qrwlock_types.h>