diff mbox series

[printk,v2,2/4] printk: Add this_cpu_in_panic()

Message ID 20231013204340.1112036-3-john.ogness@linutronix.de
State New
Headers
Series fix console flushing on panic |

Commit Message

John Ogness Oct. 13, 2023, 8:43 p.m. UTC 
  There is already panic_in_progress() and other_cpu_in_panic(),
but checking if the current CPU is the panic CPU must still be
open coded.

Add this_cpu_in_panic() to complete the set.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 kernel/printk/internal.h |  1 +
 kernel/printk/printk.c   | 43 +++++++++++++++++++++-------------------
 2 files changed, 24 insertions(+), 20 deletions(-)

Comments

Petr Mladek Oct. 16, 2023, 1:14 p.m. UTC | #1 
On Fri 2023-10-13 22:49:38, John Ogness wrote:
> There is already panic_in_progress() and other_cpu_in_panic(),
> but checking if the current CPU is the panic CPU must still be
> open coded.
> 
> Add this_cpu_in_panic() to complete the set.
> 
> Signed-off-by: John Ogness <john.ogness@linutronix.de>

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr
diff mbox series

Patch

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 7d4979d5c3ce..2397734c0fd2 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -105,3 +105,4 @@  struct printk_message {
 };
 
 bool other_cpu_in_panic(void);
+bool this_cpu_in_panic(void);
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index abb6a50ee26f..19b752880879 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -351,6 +351,29 @@  static bool panic_in_progress(void)
 	return unlikely(atomic_read(&panic_cpu) != PANIC_CPU_INVALID);
 }
 
+/* Return true if a panic is in progress on the current CPU. */
+bool this_cpu_in_panic(void)
+{
+	/*
+	 * We can use raw_smp_processor_id() here because it is impossible for
+	 * the task to be migrated to the panic_cpu, or away from it. If
+	 * panic_cpu has already been set, and we're not currently executing on
+	 * that CPU, then we never will be.
+	 */
+	return unlikely(atomic_read(&panic_cpu) == raw_smp_processor_id());
+}
+
+/*
+ * Return true if a panic is in progress on a remote CPU.
+ *
+ * On true, the local CPU should immediately release any printing resources
+ * that may be needed by the panic CPU.
+ */
+bool other_cpu_in_panic(void)
+{
+	return (panic_in_progress() && !this_cpu_in_panic());
+}
+
 /*
  * This is used for debugging the mess that is the VT code by
  * keeping track if we have the console semaphore held. It's
@@ -2610,26 +2633,6 @@  static int console_cpu_notify(unsigned int cpu)
 	return 0;
 }
 
-/*
- * Return true if a panic is in progress on a remote CPU.
- *
- * On true, the local CPU should immediately release any printing resources
- * that may be needed by the panic CPU.
- */
-bool other_cpu_in_panic(void)
-{
-	if (!panic_in_progress())
-		return false;
-
-	/*
-	 * We can use raw_smp_processor_id() here because it is impossible for
-	 * the task to be migrated to the panic_cpu, or away from it. If
-	 * panic_cpu has already been set, and we're not currently executing on
-	 * that CPU, then we never will be.
-	 */
-	return atomic_read(&panic_cpu) != raw_smp_processor_id();
-}
-
 /**
  * console_lock - block the console subsystem from printing
  *