Linux-Fsdevel Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Greg KH <gregkh@linuxfoundation.org>
To: Jonathan Adams <jwadams@google.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	netdev@vger.kernel.org, kvm@vger.kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Jim Mattson <jmattson@google.com>,
	David Rientjes <rientjes@google.com>,
	Justin TerAvest <teravest@google.com>
Subject: Re: [RFC PATCH 1/7] core/metricfs: Create metricfs, standardized files under debugfs.
Date: Sat, 8 Aug 2020 07:41:43 +0200	[thread overview]
Message-ID: <20200808054143.GB1037591@kroah.com> (raw)
In-Reply-To: <20200807212916.2883031-2-jwadams@google.com>

debugfs interaction nits:

On Fri, Aug 07, 2020 at 02:29:10PM -0700, Jonathan Adams wrote:
> +static struct dentry *metricfs_init_dentry(void)
> +{
> +	static int once;
> +
> +	if (d_metricfs)
> +		return d_metricfs;
> +
> +	if (!debugfs_initialized())
> +		return NULL;
> +
> +	d_metricfs = debugfs_create_dir("metricfs", NULL);
> +
> +	if (!d_metricfs && !once) {

As it is impossible for d_metricfs to ever be NULL, why are you checking
it?

> +		once = 1;
> +		pr_warn("Could not create debugfs directory 'metricfs'\n");

There is a pr_warn_once I think, but again, how can this ever trigger?

> +		return NULL;
> +	}
> +
> +	return d_metricfs;
> +}
> +
> +/* We always cast in and out to struct dentry. */
> +struct metricfs_subsys {
> +	struct dentry dentry;
> +};
> +
> +static struct dentry *metricfs_create_file(const char *name,
> +					   mode_t mode,
> +					   struct dentry *parent,
> +					   void *data,
> +					   const struct file_operations *fops)
> +{
> +	struct dentry *ret;
> +
> +	ret = debugfs_create_file(name, mode, parent, data, fops);
> +	if (!ret)
> +		pr_warn("Could not create debugfs '%s' entry\n", name);

As ret can never be NULL, why check?

There is no need to ever check debugfs return values, just keep on
going, that's the design of it.

thanks,

greg k-h

  reply	other threads:[~2020-08-08  5:41 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-07 21:29 [RFC PATCH 0/7] metricfs metric file system and examples Jonathan Adams
2020-08-07 21:29 ` [RFC PATCH 1/7] core/metricfs: Create metricfs, standardized files under debugfs Jonathan Adams
2020-08-08  5:41   ` Greg KH [this message]
2020-08-07 21:29 ` [RFC PATCH 2/7] core/metricfs: add support for percpu metricfs files Jonathan Adams
2020-08-08  5:43   ` Greg KH
2020-08-07 21:29 ` [RFC PATCH 3/7] core/metricfs: metric for kernel warnings Jonathan Adams
2020-08-08  5:45   ` Greg KH
2020-08-07 21:29 ` [RFC PATCH 4/7] core/metricfs: expose softirq information through metricfs Jonathan Adams
2020-08-08  5:46   ` Greg KH
2020-08-07 21:29 ` [RFC PATCH 5/7] core/metricfs: expose scheduler stat " Jonathan Adams
2020-08-07 21:29 ` [RFC PATCH 6/7] core/metricfs: expose x86-specific irq " Jonathan Adams
2020-08-13 10:11   ` Thomas Gleixner
2020-08-13 11:47     ` Paolo Bonzini
2020-08-13 12:13       ` Thomas Gleixner
2020-08-13 14:10         ` Paolo Bonzini
2020-08-13 14:21           ` Thomas Gleixner
2020-08-07 21:29 ` [RFC PATCH 7/7] net-metricfs: Export /proc/net/dev via metricfs Jonathan Adams
2020-08-08  2:06 ` [RFC PATCH 0/7] metricfs metric file system and examples Andrew Lunn
2020-08-08 15:59   ` David Ahern
2020-08-10 18:20     ` Jakub Kicinski
2020-08-10  9:23 ` Pavel Machek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200808054143.GB1037591@kroah.com \
    --to=gregkh@linuxfoundation.org \
    --cc=jmattson@google.com \
    --cc=jwadams@google.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=rientjes@google.com \
    --cc=teravest@google.com \
    --subject='Re: [RFC PATCH 1/7] core/metricfs: Create metricfs, standardized files under debugfs.' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).