[PATCH 2/7] use smp_call_function_single() in arch/x86/kernel/acpi/cstate.c

From: Rusty Russell
Date: Sun Apr 12 2009 - 20:06:59 EST


From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

Attempting to rid us of the problematic work_on_cpu(). Just use
smp_call_function_single() here.

(Includes fix from Wu Fengguang <fengguang.wu@xxxxxxxxx>)

Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Zhao Yakui <yakui.zhao@xxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
arch/x86/kernel/acpi/cstate.c | 36 ++++++++++++++++++++++++------------
1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -53,6 +53,12 @@ struct cstate_entry {
};
static struct cstate_entry *cpu_cstate_entry; /* per CPU ptr */

+/* Used for the cross-CPU calls */
+struct acpi_processor_cx_cross_cpu {
+ struct acpi_processor_cx *cx;
+ long retval;
+};
+
static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];

#define MWAIT_SUBSTATE_MASK (0xf)
@@ -67,10 +73,10 @@ static short mwait_supported[ACPI_PROCES

#define NATIVE_CSTATE_BEYOND_HALT (2)

-static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
+static void acpi_processor_ffh_cstate_probe_cpu(void *_cxcc)
{
- struct acpi_processor_cx *cx = _cx;
- long retval;
+ struct acpi_processor_cx_cross_cpu *cxcc = _cxcc;
+ struct acpi_processor_cx *cx = cxcc->cx;
unsigned int eax, ebx, ecx, edx;
unsigned int edx_part;
unsigned int cstate_type; /* C-state type and not ACPI C-state type */
@@ -84,16 +90,16 @@ static long acpi_processor_ffh_cstate_pr
edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;

- retval = 0;
+ cxcc->retval = 0;
if (num_cstate_subtype < (cx->address & MWAIT_SUBSTATE_MASK)) {
- retval = -1;
+ cxcc->retval = -1;
goto out;
}

/* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
!(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
- retval = -1;
+ cxcc->retval = -1;
goto out;
}

@@ -107,7 +113,7 @@ static long acpi_processor_ffh_cstate_pr
ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
cx->address);
out:
- return retval;
+ return;
}

int acpi_processor_ffh_cstate_probe(unsigned int cpu,
@@ -115,6 +121,7 @@ int acpi_processor_ffh_cstate_probe(unsi
{
struct cstate_entry *percpu_entry;
struct cpuinfo_x86 *c = &cpu_data(cpu);
+ struct acpi_processor_cx_cross_cpu cxcc = { .cx = cx, };
long retval;

if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
@@ -127,13 +134,18 @@ int acpi_processor_ffh_cstate_probe(unsi
percpu_entry->states[cx->index].eax = 0;
percpu_entry->states[cx->index].ecx = 0;

- /* Make sure we are running on right CPU */
+ /* Run acpi_processor_ffh_cstate_probe_cpu() on the target CPU */

- retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx);
+ retval = smp_call_function_single(cpu,
+ acpi_processor_ffh_cstate_probe_cpu, &cxcc, 1);
if (retval == 0) {
- /* Use the hint in CST */
- percpu_entry->states[cx->index].eax = cx->address;
- percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
+ retval = cxcc.retval;
+ if (retval == 0) {
+ /* Use the hint in CST */
+ percpu_entry->states[cx->index].eax = cx->address;
+ percpu_entry->states[cx->index].ecx =
+ MWAIT_ECX_INTERRUPT_BREAK;
+ }
}
return retval;
}

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