MIPS: Allow kernel use of LL/SC to be separate from the presence of LL/SC.
On some CPUs, it is more efficient to disable and enable interrupts in the
kernel rather than use ll/sc for atomic operations. But if we were to set
cpu_has_llsc to false, we would break the userspace futex interface (in
asm/futex.h).
We separate the two concepts, with a new predicate kernel_uses_llsc, that
lets us disable the kernel's use of ll/sc while still allowing the futex
code to use it.
Also there were a couple of cases in bitops.h where we were using ll/sc
unconditionally even if cpu_has_llsc were false.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/local.h b/arch/mips/include/asm/local.h
index f96fd59..361f4f16 100644
--- a/arch/mips/include/asm/local.h
+++ b/arch/mips/include/asm/local.h
@@ -29,7 +29,7 @@
{
unsigned long result;
- if (cpu_has_llsc && R10000_LLSC_WAR) {
+ if (kernel_uses_llsc && R10000_LLSC_WAR) {
unsigned long temp;
__asm__ __volatile__(
@@ -43,7 +43,7 @@
: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
: "Ir" (i), "m" (l->a.counter)
: "memory");
- } else if (cpu_has_llsc) {
+ } else if (kernel_uses_llsc) {
unsigned long temp;
__asm__ __volatile__(
@@ -74,7 +74,7 @@
{
unsigned long result;
- if (cpu_has_llsc && R10000_LLSC_WAR) {
+ if (kernel_uses_llsc && R10000_LLSC_WAR) {
unsigned long temp;
__asm__ __volatile__(
@@ -88,7 +88,7 @@
: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
: "Ir" (i), "m" (l->a.counter)
: "memory");
- } else if (cpu_has_llsc) {
+ } else if (kernel_uses_llsc) {
unsigned long temp;
__asm__ __volatile__(