linux-kernel - [RFC][PATCH 3/3] printk: do not preliminary split up cont buffer

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Date:   Tue,  2 Oct 2018 11:38:36 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Petr Mladek <pmladek@...e.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Dmitriy Vyukov <dvyukov@...gle.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Tejun Heo <tj@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: [RFC][PATCH 3/3] printk: do not preliminary split up cont buffer

We have a proper 'overflow' check which tells us that we need to
split up existing cont buffer in separate records:

	if (cont.len + len > sizeof(cont.buf))
		cont_flush();

At the same time we also have one extra flush: "if cont buffer is
80% full then split it up" in cont_add():

	if (cont.len > (sizeof(cont.buf) * 80) / 100)
		cont_flush();

This looks to be redundant, since the existing "overflow" check
should work just fine, so remove this 80% check and wait for either
a normal cont termination \n, for preliminary flush due to
possible buffer overflow or for preliminary flush due to cont race.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
 kernel/printk/printk.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index aea37b7927dd..1856db8128c6 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1822,9 +1822,6 @@ static bool cont_add(int facility, int level, enum log_flags flags, const char *
 		cont_flush();
 	}
 
-	if (cont.len > (sizeof(cont.buf) * 80) / 100)
-		cont_flush();
-
 	return true;
 }
 
-- 
2.19.0