From: Thomas Gleixner <[email protected]>
Now that the core code drops sparse_irq_lock after the idle thread
synchronized, it's pointless to wait for the AP to mark itself online.
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Michael Kelley <[email protected]>
---
arch/x86/kernel/smpboot.c | 26 ++------------------------
1 file changed, 2 insertions(+), 24 deletions(-)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -275,7 +275,6 @@ static void notrace start_secondary(void
* half valid vector space.
*/
lock_vector_lock();
- /* Sync point with do_wait_cpu_online() */
set_cpu_online(smp_processor_id(), true);
lapic_online();
unlock_vector_lock();
@@ -1104,20 +1103,6 @@ static int wait_cpu_initialized(unsigned
return 0;
}
-/*
- * Bringup step three: Wait for the target AP to reach set_cpu_online() in
- * start_secondary().
- */
-static void wait_cpu_online(unsigned int cpu)
-{
- /*
- * Wait for the AP to mark itself online, so the core caller
- * can drop sparse_irq_lock.
- */
- while (!cpu_online(cpu))
- schedule();
-}
-
static int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
{
int apicid = apic->cpu_present_to_apicid(cpu);
@@ -1164,16 +1149,9 @@ int native_cpu_up(unsigned int cpu, stru
int ret;
ret = native_kick_ap(cpu, tidle);
- if (ret)
- goto out;
-
- ret = wait_cpu_initialized(cpu);
- if (ret)
- goto out;
-
- wait_cpu_online(cpu);
+ if (!ret)
+ ret = wait_cpu_initialized(cpu);
-out:
/* Cleanup possible dangling ends... */
if (x86_platform.legacy.warm_reset)
smpboot_restore_warm_reset_vector();
The following commit has been merged into the smp/core branch of tip:
Commit-ID: e464640cf7af12f3c2748065936b95eae1f735ba
Gitweb: https://git.kernel.org/tip/e464640cf7af12f3c2748065936b95eae1f735ba
Author: Thomas Gleixner <[email protected]>
AuthorDate: Fri, 12 May 2023 23:07:22 +02:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Mon, 15 May 2023 13:44:54 +02:00
x86/smpboot: Remove wait for cpu_online()
Now that the core code drops sparse_irq_lock after the idle thread
synchronized, it's pointless to wait for the AP to mark itself online.
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Tested-by: Michael Kelley <[email protected]>
Tested-by: Oleksandr Natalenko <[email protected]>
Tested-by: Helge Deller <[email protected]> # parisc
Tested-by: Guilherme G. Piccoli <[email protected]> # Steam Deck
Link: https://lore.kernel.org/r/[email protected]
---
arch/x86/kernel/smpboot.c | 26 ++------------------------
1 file changed, 2 insertions(+), 24 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3f731be..4349e8a 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -275,7 +275,6 @@ static void notrace start_secondary(void *unused)
* half valid vector space.
*/
lock_vector_lock();
- /* Sync point with do_wait_cpu_online() */
set_cpu_online(smp_processor_id(), true);
lapic_online();
unlock_vector_lock();
@@ -1104,20 +1103,6 @@ static int wait_cpu_initialized(unsigned int cpu)
return 0;
}
-/*
- * Bringup step three: Wait for the target AP to reach set_cpu_online() in
- * start_secondary().
- */
-static void wait_cpu_online(unsigned int cpu)
-{
- /*
- * Wait for the AP to mark itself online, so the core caller
- * can drop sparse_irq_lock.
- */
- while (!cpu_online(cpu))
- schedule();
-}
-
static int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
{
int apicid = apic->cpu_present_to_apicid(cpu);
@@ -1164,16 +1149,9 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
int ret;
ret = native_kick_ap(cpu, tidle);
- if (ret)
- goto out;
-
- ret = wait_cpu_initialized(cpu);
- if (ret)
- goto out;
-
- wait_cpu_online(cpu);
+ if (!ret)
+ ret = wait_cpu_initialized(cpu);
-out:
/* Cleanup possible dangling ends... */
if (x86_platform.legacy.warm_reset)
smpboot_restore_warm_reset_vector();