[PATCH AUTOSEL 6.8 18/68] printk: Add this_cpu_in_panic()

Sasha Levin
2024-03-29T12:27:23Z

From: John Ogness <john.ogness@linutronix.de>

[ Upstream commit 36652d0f3bf34899e82d31a5fa9e2bdd02fd6381 ]

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>
Link: https://lore.kernel.org/r/20240207134103.1357162-8-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 6c2afee5ef620..ac2d9750e5f81 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -130,6 +130,7 @@ struct printk_message {
};

bool other_cpu_in_panic(void);
+bool this_cpu_in_panic(void);
bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
bool is_extended, bool may_supress);

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index d9f20d222293b..742fb479b1d60 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -347,6 +347,29 @@ 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
@@ -2600,26 +2623,6 @@ 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
*
--
2.43.0