linux-kernel - [PATCH 04/15] print_integer, proc: rewrite /proc/self via print

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Message-Id: <20200420205743.19964-4-adobriyan@gmail.com>
Date:   Mon, 20 Apr 2020 23:57:32 +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 04/15] print_integer, proc: rewrite /proc/self via print_integer()

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
 fs/proc/internal.h | 1 +
 fs/proc/self.c     | 8 ++++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 917cc85e3466..8abfd2fa0963 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -13,6 +13,7 @@
 #include <linux/binfmts.h>
 #include <linux/sched/coredump.h>
 #include <linux/sched/task.h>
+#include "../../lib/print-integer.h"
 
 struct ctl_table_header;
 struct mempolicy;
diff --git a/fs/proc/self.c b/fs/proc/self.c
index 57c0a1047250..c8a1662e2cfd 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -14,15 +14,19 @@ static const char *proc_self_get_link(struct dentry *dentry,
 {
 	struct pid_namespace *ns = proc_pid_ns(inode);
 	pid_t tgid = task_tgid_nr_ns(current, ns);
+	char buf[10 + 1];
+	char *p = buf + sizeof(buf);
 	char *name;
 
 	if (!tgid)
 		return ERR_PTR(-ENOENT);
 	/* max length of unsigned int in decimal + NULL term */
-	name = kmalloc(10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);
+	name = kmalloc(sizeof(buf), dentry ? GFP_KERNEL : GFP_ATOMIC);
 	if (unlikely(!name))
 		return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
-	sprintf(name, "%u", tgid);
+	*--p = '\0';
+	p = _print_integer_u32(p, tgid);
+	memcpy(name, p, buf + sizeof(buf) - p);
 	set_delayed_call(done, kfree_link, name);
 	return name;
 }
-- 
2.24.1