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	Fri, 27 Feb 2026 20:18:24 +0000
Date: Fri, 27 Feb 2026 20:18:24 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: AnishMulay <anishm7030@gmail.com>
Cc: rostedt@goodmis.org, mhiramat@kernel.org,
	mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tracefs: Simplify get_dname() with kmemdup_nul()
Message-ID: <20260227201824.GE3836593@ZenIV>
References: <20260227194453.213095-1-anishm7030@gmail.com>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Fri, Feb 27, 2026 at 02:44:53PM -0500, AnishMulay wrote:
> index d9d8932a7b9c9..86ba8dc25aaef 100644
> --- a/fs/tracefs/inode.c
> +++ b/fs/tracefs/inode.c
> @@ -96,17 +96,7 @@ static struct tracefs_dir_ops {
>  
>  static char *get_dname(struct dentry *dentry)
>  {
> -	const char *dname;
> -	char *name;
> -	int len = dentry->d_name.len;
> -
> -	dname = dentry->d_name.name;
> -	name = kmalloc(len + 1, GFP_KERNEL);
> -	if (!name)
> -		return NULL;
> -	memcpy(name, dname, len);
> -	name[len] = 0;
> -	return name;
> +	return kmemdup_nul(dentry->d_name.name, dentry->d_name.len, GFP_KERNEL);
>  }

Why not have the callers use {take,release}_dentry_name_snapshot()
instead of doing any allocations at all?

I mean,
static struct dentry *tracefs_syscall_mkdir(struct mnt_idmap *idmap,
                                            struct inode *inode, struct dentry *dentry,
                                            umode_t mode)
{
        struct tracefs_inode *ti;
        struct name_snapshot s;
        int ret;
 
        take_dentry_name_snapshot(&s, dentry);
	...
        ret = tracefs_ops.mkdir(s.name.name);
	release_dentry_name_snapshot(&s);
	...
}

and similar on the rmdir side.  Then remove get_dname()...