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arch/sparc: Enable queued spinlock support for SPARC

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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>
This commit is contained in:
Babu Moger
2017-05-24 17:55:15 -06:00
committed by David S. Miller
parent 79d39e2bab
commit 145d978585
4 changed files with 14 additions and 83 deletions
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84
arch/sparc/include/asm/spinlock_64.h
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@@ -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)