Workqueue is guaranteed to be available on the target CPU by the time
acpi_processor_ffh_cstate_probe() is invoked for it. There's no
reason to use costly work_on_cpu() which involves creating and tearing
down a full kthread on each invocation to execute the probing function
on the target CPU. Use a work item instead.
Tested and works as expected.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
arch/x86/kernel/acpi/cstate.c | 35 ++++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index d2b7f27..97259f0 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -69,10 +69,16 @@ static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
#define NATIVE_CSTATE_BEYOND_HALT (2)
-static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
+struct cstate_probe_arg {
+ struct work_struct work;
+ struct acpi_processor_cx *cx;
+ int ret;
+};
+
+static void acpi_processor_ffh_cstate_probe_cpu(struct work_struct *work)
{
- struct acpi_processor_cx *cx = _cx;
- long retval;
+ struct cstate_probe_arg *arg = container_of(work, struct cstate_probe_arg, work);
+ struct acpi_processor_cx *cx = arg->cx;
unsigned int eax, ebx, ecx, edx;
unsigned int edx_part;
unsigned int cstate_type; /* C-state type and not ACPI C-state type */
@@ -86,17 +92,16 @@ static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
- retval = 0;
if (num_cstate_subtype < (cx->address & MWAIT_SUBSTATE_MASK)) {
- retval = -1;
- goto out;
+ arg->ret = -1;
+ return;
}
/* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
!(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
- retval = -1;
- goto out;
+ arg->ret = -1;
+ return;
}
if (!mwait_supported[cstate_type]) {
@@ -108,8 +113,7 @@ static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
snprintf(cx->desc,
ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
cx->address);
-out:
- return retval;
+ arg->ret = 0;
}
int acpi_processor_ffh_cstate_probe(unsigned int cpu,
@@ -117,7 +121,7 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
{
struct cstate_entry *percpu_entry;
struct cpuinfo_x86 *c = &cpu_data(cpu);
- long retval;
+ struct cstate_probe_arg arg = { .cx = cx };
if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
return -1;
@@ -130,9 +134,10 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
percpu_entry->states[cx->index].ecx = 0;
/* Make sure we are running on right CPU */
-
- retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx);
- if (retval == 0) {
+ INIT_WORK_ONSTACK(&arg.work, acpi_processor_ffh_cstate_probe_cpu);
+ schedule_work_on(cpu, &arg.work);
+ flush_work(&arg.work);
+ if (arg.ret == 0) {
/* Use the hint in CST */
percpu_entry->states[cx->index].eax = cx->address;
percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
@@ -146,7 +151,7 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
if ((c->x86_vendor == X86_VENDOR_INTEL) && !(reg->access_size & 0x2))
cx->bm_sts_skip = 1;
- return retval;
+ return arg.ret;
}
EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
--
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