Messages in this thread | | | Date | Thu, 9 Sep 2021 07:34:31 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] sysfs: Remove page boundary align limitation on sysfs_emit and sysfs_emit_at |
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On Thu, Sep 09, 2021 at 05:27:49AM +0000, Yu, Lang wrote: > [AMD Official Use Only] > > > > >-----Original Message----- > >From: Joe Perches <joe@perches.com> > >Sent: Thursday, September 9, 2021 1:06 PM > >To: Yu, Lang <Lang.Yu@amd.com>; Greg Kroah-Hartman > ><gregkh@linuxfoundation.org>; Rafael J . Wysocki <rafael@kernel.org>; linux- > >kernel@vger.kernel.org > >Subject: Re: [PATCH] sysfs: Remove page boundary align limitation on sysfs_emit > >and sysfs_emit_at > > > >On Wed, 2021-09-08 at 20:07 +0800, Lang Yu wrote: > >> The key purpose of sysfs_emit and sysfs_emit_at is to ensure that no > >> overrun is done. Make them more equivalent with scnprintf. > > > >I can't think of a single reason to do this. > >sysfs_emit and sysfs_emit_at are specific to sysfs. > > > >Use of these functions outside of sysfs is not desired or supported. > > > > > Thanks for your reply. But I'm still curious why you put such a limitation. > As "Documentation/filesystems/sysfs.rst" described, we can just use > scnprintf(buf, PAGE_SIZE, "%s\n", dev->name) in show functions without > such a limitation. > > But you said that " - show() should only use sysfs_emit() or sysfs_emit_at() when formatting > the value to be returned to user space. " in Documentation/filesystems/sysfs.rst. > > Some guys just try to replace scnprintf with sysfs_emit() or sysfs_emit_at() per above documents.
That is just fine in sysfs show() functions.
> But sprintf and sysfs_emit/sysfs_emit_at are not totally equivalent(e.g., page boundary align).
Which is good, it checks for more error conditions.
I fail to understand what problem you have had with this. What sysfs file was converted and had issues?
> In my opinion, we add a new api and try to replace an old api. Does we need to make it more > compatible with old api? Thanks.
There is no "old api" here. People used a wide variety of different things in sysfs file show() functions, now you can just use a single one.
thanks,
greg k-h
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