Revert "printk: add functions to prefer direct printing"

This reverts commit 2bb2b7b57f81255c13f4395ea911d6bdc70c9fe2.

The testing of 5.19 release candidates revealed missing synchronization
between early and regular console functionality.

It would be possible to start the console kthreads later as a workaround.
But it is clear that console lock serialized console drivers between
each other. It opens a big area of possible problems that were not
considered by people involved in the development and review.

printk() is crucial for debugging kernel issues and console output is
very important part of it. The number of consoles is huge and a proper
review would take some time. As a result it need to be reverted for 5.19.

Link: https://lore.kernel.org/r/YrBdjVwBOVgLfHyb@alley
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220623145157.21938-7-pmladek@suse.com

1 files changed, 0 insertions, 28 deletions

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5a6273e56b4e..b49c6ff6dca0 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -362,34 +362,6 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
 static DEFINE_MUTEX(syslog_lock);
 
 #ifdef CONFIG_PRINTK
-static atomic_t printk_prefer_direct = ATOMIC_INIT(0);
-
-/**
- * printk_prefer_direct_enter - cause printk() calls to attempt direct
- *                              printing to all enabled consoles
- *
- * Since it is not possible to call into the console printing code from any
- * context, there is no guarantee that direct printing will occur.
- *
- * This globally effects all printk() callers.
- *
- * Context: Any context.
- */
-void printk_prefer_direct_enter(void)
-{
-	atomic_inc(&printk_prefer_direct);
-}
-
-/**
- * printk_prefer_direct_exit - restore printk() behavior
- *
- * Context: Any context.
- */
-void printk_prefer_direct_exit(void)
-{
-	WARN_ON(atomic_dec_if_positive(&printk_prefer_direct) < 0);
-}
-
 DECLARE_WAIT_QUEUE_HEAD(log_wait);
 /* All 3 protected by @syslog_lock. */
 /* the next printk record to read by syslog(READ) or /proc/kmsg */