[PATCH v4 3/4] Revert "printk: lock/unlock console only for new logbuf entries"

From: John Ogness
Date: Tue Jul 07 2020 - 10:59:45 EST


This reverts commit 3ac37a93fa9217e576bebfd4ba3e80edaaeb2289.

This optimization will not apply once the transition to a lockless
printk is complete. Rather than porting this optimization through
the transition only to remove it anyway, just revert it now to
simplify the transition.

Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
---
kernel/printk/printk.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b71eaf5f5a86..1b41e1b98221 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1981,9 +1981,8 @@ asmlinkage int vprintk_emit(int facility, int level,
const char *fmt, va_list args)
{
int printed_len;
- bool in_sched = false, pending_output;
+ bool in_sched = false;
unsigned long flags;
- u64 curr_log_seq;

/* Suppress unimportant messages after panic happens */
if (unlikely(suppress_printk))
@@ -1999,13 +1998,11 @@ asmlinkage int vprintk_emit(int facility, int level,

/* This stops the holder of console_sem just where we want him */
logbuf_lock_irqsave(flags);
- curr_log_seq = log_next_seq;
printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args);
- pending_output = (curr_log_seq != log_next_seq);
logbuf_unlock_irqrestore(flags);

/* If called from the scheduler, we can not call up(). */
- if (!in_sched && pending_output) {
+ if (!in_sched) {
/*
* Disable preemption to avoid being preempted while holding
* console_sem which would prevent anyone from printing to
@@ -2022,8 +2019,7 @@ asmlinkage int vprintk_emit(int facility, int level,
preempt_enable();
}

- if (pending_output)
- wake_up_klogd();
+ wake_up_klogd();
return printed_len;
}
EXPORT_SYMBOL(vprintk_emit);
--
2.20.1