[PATCH printk v2 12/12] printk: remove @console_locked

John Ogness
2022-04-06T01:54:04Z

The static global variable @console_locked is used to help debug
VT code to make sure that certain code paths are running with
the console_lock held. However, this information is also available
with the static global variable @console_kthreads_blocked (for
locking via console_lock()), and the static global variable
@console_kthreads_active (for locking via console_trylock()).

Remove @console_locked and update is_console_locked() to use the
alternative variables.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
---
kernel/printk/printk.c | 29 ++++++++++++++---------------
1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index a5525a7b7bc5..2da66adac87e 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -340,15 +340,7 @@ static void console_kthreads_unblock(void)
console_kthreads_blocked = false;
}

-/*
- * This is used for debugging the mess that is the VT code by
- * keeping track if we have the console semaphore held. It's
- * definitely not the perfect debug tool (we don't know if _WE_
- * hold it and are racing, but it helps tracking those weird code
- * paths in the console code where we end up in places I want
- * locked without the console semaphore held).
- */
-static int console_locked, console_suspended;
+static int console_suspended;

/*
* Array of consoles built from command line options (console=)
@@ -2675,7 +2667,6 @@ void console_lock(void)
if (console_suspended)
return;
console_kthreads_block();
- console_locked = 1;
console_may_schedule = 1;
}
EXPORT_SYMBOL(console_lock);
@@ -2700,15 +2691,26 @@ int console_trylock(void)
up_console_sem();
return 0;
}
- console_locked = 1;
console_may_schedule = 0;
return 1;
}
EXPORT_SYMBOL(console_trylock);

+/*
+ * This is used to help to make sure that certain paths within the VT code are
+ * running with the console lock held. It is definitely not the perfect debug
+ * tool (it is not known if the VT code is the task holding the console lock),
+ * but it helps tracking those weird code paths in the console code such as
+ * when the console is suspended: where the console is not locked but no
+ * console printing may occur.
+ *
+ * Note: This returns true when the console is suspended but is not locked.
+ * This is intentional because the VT code must consider that situation
+ * the same as if the console was locked.
+ */
int is_console_locked(void)
{
- return (console_locked || atomic_read(&console_kthreads_active));
+ return (console_kthreads_blocked || atomic_read(&console_kthreads_active));
}
EXPORT_SYMBOL(is_console_locked);

@@ -2759,8 +2761,6 @@ static inline bool console_is_usable(struct console *con)

static void __console_unlock(void)
{
- console_locked = 0;
-
/*
* Depending on whether console_lock() or console_trylock() was used,
* appropriately allow the kthread printers to continue.
@@ -3058,7 +3058,6 @@ void console_unblank(void)
} else
console_lock();

- console_locked = 1;
console_may_schedule = 0;
for_each_console(c)
if ((c->flags & CON_ENABLED) && c->unblank)
--
2.30.2