From: Alan Stern <stern@rowland.harvard.edu>
To: NeilBrown <neilb@suse.de>
Cc: alsa-devel@alsa-project.org, Randy Dunlap <rdunlap@infradead.org>,
Zzy Wysm <zzy@zzywysm.com>,
linux-kernel@vger.kernel.org,
"J. Bruce Fields" <bfields@fieldses.org>,
target-devel@vger.kernel.org, Dave Jiang <dave.jiang@intel.com>,
linux-scsi@vger.kernel.org, linux-nvdimm@lists.01.org,
Vishal Verma <vishal.l.verma@intel.com>,
Matthew Wilcox <willy@infradead.org>,
Chuck Lever <chuck.lever@oracle.com>,
linux-input@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Dan Williams <dan.j.williams@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-nfs@vger.kernel.org,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Takashi Iwai <tiwai@suse.com>,
linux-usb@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Johannes Berg <johannes@sipsolutions.net>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 5/9] usb: fix empty-body warning in sysfs.c
Date: Tue, 21 Apr 2020 09:58:02 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.2004210956590.20254-100000@netrider.rowland.org> (raw)
In-Reply-To: <87368xskga.fsf@notabene.neil.brown.name>
On Tue, 21 Apr 2020, NeilBrown wrote:
> On Sat, Apr 18 2020, Alan Stern wrote:
>
> > On Sat, 18 Apr 2020, Matthew Wilcox wrote:
> >
> >> On Sat, Apr 18, 2020 at 11:41:07AM -0700, Randy Dunlap wrote:
> >> > +++ linux-next-20200327/drivers/usb/core/sysfs.c
> >> > @@ -1263,7 +1263,7 @@ void usb_create_sysfs_intf_files(struct
> >> > if (!alt->string && !(udev->quirks & USB_QUIRK_CONFIG_INTF_STRINGS))
> >> > alt->string = usb_cache_string(udev, alt->desc.iInterface);
> >> > if (alt->string && device_create_file(&intf->dev, &dev_attr_interface))
> >> > - ; /* We don't actually care if the function fails. */
> >> > + do_empty(); /* We don't actually care if the function fails. */
> >> > intf->sysfs_files_created = 1;
> >> > }
> >>
> >> Why not just?
> >>
> >> + if (alt->string)
> >> + device_create_file(&intf->dev, &dev_attr_interface);
> >
> > This is another __must_check function call.
> >
> > The reason we don't care if the call fails is because the file
> > being created holds the USB interface string descriptor, something
> > which is purely informational and hardly ever gets set (and no doubt
> > gets used even less often).
> >
> > Is this another situation where the comment should be expanded and the
> > code modified to include a useless test and cast-to-void?
> >
> > Or should device_create_file() not be __must_check after all?
>
> One approach to dealing with __must_check function that you don't want
> to check is to cause failure to call
> pr_debug("usb: interface descriptor file not created");
> or similar. It silences the compiler, serves as documentation, and
> creates a message that is almost certainly never seen.
>
> This is what I did in drivers/md/md.c...
>
> if (mddev->kobj.sd &&
> sysfs_create_group(&mddev->kobj, &md_bitmap_group))
> pr_debug("pointless warning\n");
>
> (I give better warnings elsewhere - I must have run out of patience by
> this point).
That's a decent idea. I'll do something along those lines.
Alan Stern
next prev parent reply other threads:[~2020-04-21 13:59 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-18 18:41 [RFC PATCH 0/9] fix -Wempty-body build warnings Randy Dunlap
2020-04-18 18:41 ` [RFC PATCH 1/9] kernel.h: add do_empty() macro Randy Dunlap
2020-04-18 18:44 ` Joe Perches
2020-04-18 18:49 ` Randy Dunlap
2020-04-18 22:20 ` Bart Van Assche
2020-04-18 22:24 ` Randy Dunlap
2020-04-18 18:41 ` [PATCH 2/9] fs: fix empty-body warning in posix_acl.c Randy Dunlap
2020-04-18 18:53 ` Linus Torvalds
2020-04-18 18:55 ` Randy Dunlap
2020-04-20 19:58 ` [PATCH 2/9] " Zzy Wysm
2020-04-18 18:41 ` [PATCH 3/9] input: fix empty-body warning in synaptics.c Randy Dunlap
2020-04-18 18:41 ` [PATCH 4/9] sound: fix empty-body warning in vx_core.c Randy Dunlap
2020-04-18 18:41 ` [PATCH 5/9] usb: fix empty-body warning in sysfs.c Randy Dunlap
2020-04-18 18:44 ` Matthew Wilcox
2020-04-18 18:46 ` Randy Dunlap
2020-04-18 19:54 ` Alan Stern
2020-04-21 1:20 ` NeilBrown
2020-04-21 13:58 ` Alan Stern [this message]
2020-04-18 18:41 ` [PATCH 6/9] nfsd: fix empty-body warning in nfs4state.c Randy Dunlap
2020-04-18 18:45 ` Chuck Lever
2020-04-18 18:53 ` Joe Perches
2020-04-18 18:57 ` Randy Dunlap
2020-04-18 22:28 ` Trond Myklebust
2020-04-18 22:32 ` Randy Dunlap
2020-04-18 22:33 ` Chuck Lever
2020-04-19 9:32 ` Sergei Shtylyov
2020-04-18 18:41 ` [PATCH 7/9] drivers/base: fix empty-body warnings in devcoredump.c Randy Dunlap
2020-04-18 18:50 ` Matthew Wilcox
2020-04-18 18:53 ` Randy Dunlap
2020-04-18 18:55 ` Joe Perches
2020-04-18 19:13 ` Matthew Wilcox
2020-04-18 19:16 ` Johannes Berg
2020-04-18 19:15 ` Linus Torvalds
2020-04-19 12:03 ` Greg Kroah-Hartman
2020-04-19 6:02 ` Greg Kroah-Hartman
2020-04-19 6:04 ` Greg Kroah-Hartman
2020-04-18 18:41 ` [PATCH 8/9] dax: fix empty-body warnings in bus.c Randy Dunlap
2020-04-19 8:15 ` Christoph Hellwig
2020-04-18 18:41 ` [PATCH 9/9] target: fix empty-body warning in target_core_pscsi.c Randy Dunlap
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=Pine.LNX.4.44L0.2004210956590.20254-100000@netrider.rowland.org \
--to=stern@rowland.harvard.edu \
--cc=akpm@linux-foundation.org \
--cc=alsa-devel@alsa-project.org \
--cc=bfields@fieldses.org \
--cc=chuck.lever@oracle.com \
--cc=dan.j.williams@intel.com \
--cc=dave.jiang@intel.com \
--cc=dmitry.torokhov@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=johannes@sipsolutions.net \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-input@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nfs@vger.kernel.org \
--cc=linux-nvdimm@lists.01.org \
--cc=linux-scsi@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=neilb@suse.de \
--cc=rdunlap@infradead.org \
--cc=target-devel@vger.kernel.org \
--cc=tiwai@suse.com \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
--cc=vishal.l.verma@intel.com \
--cc=willy@infradead.org \
--cc=zzy@zzywysm.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).