linux-kernel - [PATCH 08/15] print_integer, proc: rewrite /proc/uptime via print

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Message-Id: <20200420205743.19964-8-adobriyan@gmail.com>
Date:   Mon, 20 Apr 2020 23:57:36 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     adobriyan@...il.com, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, pmladek@...e.com,
        rostedt@...dmis.org, sergey.senozhatsky@...il.com,
        andriy.shevchenko@...ux.intel.com, linux@...musvillemoes.dk
Subject: [PATCH 08/15] print_integer, proc: rewrite /proc/uptime via print_integer()

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
 fs/proc/uptime.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 5a1b228964fb..a8190078d595 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -8,10 +8,14 @@
 #include <linux/time_namespace.h>
 #include <linux/kernel_stat.h>
 
+#include "../../lib/print-integer.h"
+
 static int uptime_proc_show(struct seq_file *m, void *v)
 {
 	struct timespec64 uptime;
 	struct timespec64 idle;
+	char buf[(LEN_UL + 1 + 2 + 1) * 2];
+	char *p = buf + sizeof(buf);
 	u64 nsec;
 	u32 rem;
 	int i;
@@ -25,11 +29,21 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 
 	idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
 	idle.tv_nsec = rem;
-	seq_printf(m, "%lu.%02lu %lu.%02lu\n",
-			(unsigned long) uptime.tv_sec,
-			(uptime.tv_nsec / (NSEC_PER_SEC / 100)),
-			(unsigned long) idle.tv_sec,
-			(idle.tv_nsec / (NSEC_PER_SEC / 100)));
+
+	*--p = '\n';
+	--p;	/* overwritten */
+	*--p = '0';
+	(void)_print_integer_u32(p + 2, idle.tv_nsec / (NSEC_PER_SEC / 100));
+	*--p = '.';
+	p = _print_integer_ul(p, (unsigned long)idle.tv_sec);
+	*--p = ' ';
+	--p;	/* overwritten */
+	*--p = '0';
+	(void)_print_integer_u32(p + 2, uptime.tv_nsec / (NSEC_PER_SEC / 100));
+	*--p = '.';
+	p = _print_integer_ul(p, (unsigned long)uptime.tv_sec);
+
+	seq_write(m, p, buf + sizeof(buf) - p);
 	return 0;
 }
 
-- 
2.24.1