linux-kernel - Re: [PATCH] printk: remove unnecessary kmalloc() from syslog during clear

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Message-ID: <20180621065802.GA495@jagdpanzerIV>
Date:   Thu, 21 Jun 2018 15:58:02 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Namit Gupta <gupta.namit@...sung.com>
Cc:     pmladek@...e.com, sergey.senozhatsky@...il.com,
        rostedt@...dmis.org, linux-kernel@...r.kernel.org,
        pankaj.m@...sung.com, a.sahrawat@...sung.com,
        himanshu.m@...sung.com
Subject: Re: [PATCH] printk: remove unnecessary kmalloc() from syslog during
 clear

On (06/20/18 19:26), Namit Gupta wrote:
[..]
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 512f7c2..53952ce 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1348,71 +1348,80 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
>  {
>  	char *text;
>  	int len = 0;
> +	u64 next_seq;
> +	u64 seq;
> +	u32 idx;
> +
> +	if (!buf) {
> +		if (clear) {
> +			logbuf_lock_irq();
> +			clear_seq = log_next_seq;
> +			clear_idx = log_next_idx;
> +			logbuf_unlock_irq();
> +		}
> +		return 0;
> +	}

---

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 4a07e7158898..33a1e45293a5 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1395,13 +1395,11 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
 		return 0;
 	}
 
-
 	text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
 	if (!text)
 		return -ENOMEM;
 
 	logbuf_lock_irq();
-
 	/*
 	 * Find first record that fits, including all following records,
 	 * into the user-provided buffer for this dump.
@@ -1436,7 +1434,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
 		int textlen;
 
 		textlen = msg_print_text(msg, true, text,
-				LOG_LINE_MAX + PREFIX_MAX);
+					 LOG_LINE_MAX + PREFIX_MAX);
 		if (textlen < 0) {
 			len = textlen;
 			break;
---


Other than that, looks OK to me.

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

	-ss