From: Fredrik Noring <noring@nocrew.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Pete Zaitcev <zaitcev@kotori.zaitcev.us>,
linux-usb@vger.kernel.org,
Philippe Ombredanne <pombredanne@nexb.com>,
Kate Stewart <kstewart@linuxfoundation.org>
Subject: [05/22] USB: mon: no need to check return value of debugfs_create functions
Date: Tue, 29 May 2018 20:15:20 +0200 [thread overview]
Message-ID: <20180529181518.GA2244@localhost.localdomain> (raw)
Hi Greg,
On Tue, May 29, 2018 at 06:51:54PM +0200, Greg Kroah-Hartman wrote:
> On Tue, May 29, 2018 at 11:34:34AM -0500, Pete Zaitcev wrote:
> > On Tue, 29 May 2018 17:30:50 +0200
> > Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> >
> > > When calling debugfs functions, there is no need to ever check the
> > > return value. The function can work or not, but the code logic should
> > > never do something different based on this.
> >
> > Okay, fair enough. And the code works, surprisingly, even when the
> > debugfs is disabled (well, according to my review). I just have one
> > question - wouldn't it be cleaner to deprecate and remove the text
> > API altogether?
>
> If you think we can do that, sure! But what's the odds that someone
> still uses it? This patch doesn't change any real functionality.
I had some use of this text API last year, when I also discovered and
submitted and fix for its data corruption problems described in commit
a5f596830e27e "usb: usbmon: Read text within supplied buffer size".
A significant disadvantage with the text API is, as far as I understand it,
that it can drop events (due to its buffering limit) without informing API
readers (via event sequence numbers or some such).
I've found a couple of USB bugs/problems (commit d6c931ea32dc0 "USB: OHCI:
Fix NULL dereference in HCDs using HCD_LOCAL_MEM" for instance) and I'm
still investigating at least one bug possibly related to lost interrupts
where some kind of probing method could be helpful.
However, I would explore other kernel probing methods for that. Not only
because I'm curious but also because I have the impression that there are
more powerful methods available than this text API. Would you recommend
any alternatives?
Fredrik
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next reply other threads:[~2018-05-29 18:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-29 18:15 Fredrik Noring [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-05-29 16:51 [05/22] USB: mon: no need to check return value of debugfs_create functions Greg Kroah-Hartman
2018-05-29 16:34 Pete Zaitcev
2018-05-29 15:30 Greg Kroah-Hartman
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