[PATCH 4/4] x86 smpboot: remove APIC.wait_for_init_deassert and atomic init_deasserted
From: Len Brown
Date: Sun Aug 16 2015 - 11:46:54 EST
From: Len Brown <len.brown@xxxxxxxxx>
Both the per-APIC flag ".wait_for_init_deassert",
and the global atomic_t "init_deasserted"
are dead code -- remove them.
For all APIC types, "wait_for_master()"
prevents an AP from proceeding until the BSP has set
cpu_callout_mask, making "init_deasserted" {unnecessary}:
BSP: <de-assert INIT>
...
BSP: {set init_deasserted}
AP: wait_for_master()
set cpu_initialized_mask
wait for cpu_callout_mask
BSP: test cpu_initialized_mask
BSP: set cpu_callout_mask
AP: test cpu_callout_mask
AP: {wait for init_deasserted}
...
AP: <touch APIC>
Deleting the {dead code} above is necessary to enable
some parallelism in a future patch.
Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
---
arch/x86/include/asm/apic.h | 2 --
arch/x86/kernel/apic/apic_flat_64.c | 2 --
arch/x86/kernel/apic/apic_noop.c | 1 -
arch/x86/kernel/apic/apic_numachip.c | 2 --
arch/x86/kernel/apic/bigsmp_32.c | 1 -
arch/x86/kernel/apic/probe_32.c | 1 -
arch/x86/kernel/apic/x2apic_cluster.c | 1 -
arch/x86/kernel/apic/x2apic_phys.c | 1 -
arch/x86/kernel/apic/x2apic_uv_x.c | 2 --
arch/x86/kernel/smpboot.c | 16 +++-------------
10 files changed, 3 insertions(+), 26 deletions(-)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index c839363..ebf6d5e 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -313,7 +313,6 @@ struct apic {
/* wakeup_secondary_cpu */
int (*wakeup_secondary_cpu)(int apicid, unsigned long start_eip);
- bool wait_for_init_deassert;
void (*inquire_remote_apic)(int apicid);
/* apic ops */
@@ -378,7 +377,6 @@ extern struct apic *__apicdrivers[], *__apicdrivers_end[];
* APIC functionality to boot other CPUs - only used on SMP:
*/
#ifdef CONFIG_SMP
-extern atomic_t init_deasserted;
extern int wakeup_secondary_cpu_via_nmi(int apicid, unsigned long start_eip);
#endif
diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
index de918c4..f92ab36 100644
--- a/arch/x86/kernel/apic/apic_flat_64.c
+++ b/arch/x86/kernel/apic/apic_flat_64.c
@@ -191,7 +191,6 @@ static struct apic apic_flat = {
.send_IPI_all = flat_send_IPI_all,
.send_IPI_self = apic_send_IPI_self,
- .wait_for_init_deassert = false,
.inquire_remote_apic = default_inquire_remote_apic,
.read = native_apic_mem_read,
@@ -299,7 +298,6 @@ static struct apic apic_physflat = {
.send_IPI_all = physflat_send_IPI_all,
.send_IPI_self = apic_send_IPI_self,
- .wait_for_init_deassert = false,
.inquire_remote_apic = default_inquire_remote_apic,
.read = native_apic_mem_read,
diff --git a/arch/x86/kernel/apic/apic_noop.c b/arch/x86/kernel/apic/apic_noop.c
index b205cdb..0d96749 100644
--- a/arch/x86/kernel/apic/apic_noop.c
+++ b/arch/x86/kernel/apic/apic_noop.c
@@ -152,7 +152,6 @@ struct apic apic_noop = {
.wakeup_secondary_cpu = noop_wakeup_secondary_cpu,
- .wait_for_init_deassert = false,
.inquire_remote_apic = NULL,
.read = noop_apic_read,
diff --git a/arch/x86/kernel/apic/apic_numachip.c b/arch/x86/kernel/apic/apic_numachip.c
index 017149c..b548fd3 100644
--- a/arch/x86/kernel/apic/apic_numachip.c
+++ b/arch/x86/kernel/apic/apic_numachip.c
@@ -92,7 +92,6 @@ static int numachip_wakeup_secondary(int phys_apicid, unsigned long start_rip)
write_lcsr(CSR_G3_EXT_IRQ_GEN, int_gen.v);
- atomic_set(&init_deasserted, 1);
return 0;
}
@@ -235,7 +234,6 @@ static const struct apic apic_numachip __refconst = {
.send_IPI_self = numachip_send_IPI_self,
.wakeup_secondary_cpu = numachip_wakeup_secondary,
- .wait_for_init_deassert = false,
.inquire_remote_apic = NULL, /* REMRD not supported */
.read = native_apic_mem_read,
diff --git a/arch/x86/kernel/apic/bigsmp_32.c b/arch/x86/kernel/apic/bigsmp_32.c
index c4a8d63..971cf88 100644
--- a/arch/x86/kernel/apic/bigsmp_32.c
+++ b/arch/x86/kernel/apic/bigsmp_32.c
@@ -186,7 +186,6 @@ static struct apic apic_bigsmp = {
.send_IPI_all = bigsmp_send_IPI_all,
.send_IPI_self = default_send_IPI_self,
- .wait_for_init_deassert = true,
.inquire_remote_apic = default_inquire_remote_apic,
.read = native_apic_mem_read,
diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index bda4886..7694ae6 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -111,7 +111,6 @@ static struct apic apic_default = {
.send_IPI_all = default_send_IPI_all,
.send_IPI_self = default_send_IPI_self,
- .wait_for_init_deassert = true,
.inquire_remote_apic = default_inquire_remote_apic,
.read = native_apic_mem_read,
diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index ab3219b..1b6c1a4 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -272,7 +272,6 @@ static struct apic apic_x2apic_cluster = {
.send_IPI_all = x2apic_send_IPI_all,
.send_IPI_self = x2apic_send_IPI_self,
- .wait_for_init_deassert = false,
.inquire_remote_apic = NULL,
.read = native_apic_msr_read,
diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index 3ffd925..662e915 100644
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -128,7 +128,6 @@ static struct apic apic_x2apic_phys = {
.send_IPI_all = x2apic_send_IPI_all,
.send_IPI_self = x2apic_send_IPI_self,
- .wait_for_init_deassert = false,
.inquire_remote_apic = NULL,
.read = native_apic_msr_read,
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index c8d9295..4a13946 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -248,7 +248,6 @@ static int uv_wakeup_secondary(int phys_apicid, unsigned long start_rip)
APIC_DM_STARTUP;
uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
- atomic_set(&init_deasserted, 1);
return 0;
}
@@ -414,7 +413,6 @@ static struct apic __refdata apic_x2apic_uv_x = {
.send_IPI_self = uv_send_IPI_self,
.wakeup_secondary_cpu = uv_wakeup_secondary,
- .wait_for_init_deassert = false,
.inquire_remote_apic = NULL,
.read = native_apic_msr_read,
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3d992b6..70276bc 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -97,8 +97,6 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
DEFINE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info);
EXPORT_PER_CPU_SYMBOL(cpu_info);
-atomic_t init_deasserted;
-
static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
{
unsigned long flags;
@@ -146,16 +144,11 @@ static void smp_callin(void)
/*
* If waken up by an INIT in an 82489DX configuration
- * we may get here before an INIT-deassert IPI reaches
- * our local APIC. We have to wait for the IPI or we'll
- * lock up on an APIC access.
- *
- * Since CPU0 is not wakened up by INIT, it doesn't wait for the IPI.
+ * cpu_callout_mask guarantees we don't get here before
+ * an INIT_deassert IPI reaches our local APIC, so it is
+ * now safe to touch our local APIC.
*/
cpuid = smp_processor_id();
- if (apic->wait_for_init_deassert && cpuid)
- while (!atomic_read(&init_deasserted))
- cpu_relax();
/*
* (This works even if the APIC is not enabled.)
@@ -620,7 +613,6 @@ wakeup_secondary_cpu_via_init(int phys_apicid, unsigned long start_eip)
send_status = safe_apic_wait_icr_idle();
mb();
- atomic_set(&init_deasserted, 1);
/*
* Should we send STARTUP IPIs ?
@@ -861,8 +853,6 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
* the targeted processor.
*/
- atomic_set(&init_deasserted, 0);
-
if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
pr_debug("Setting warm reset code and vector.\n");
--
2.5.0.330.g130be8e
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