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

John Ogness
2023-10-13T20:43:54Z

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(-)

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
*
--
2.39.2