Re: Try/catch for modules?

From: Rik van Riel <riel@surriel.com>
To: "Martin Galvan" <omgalvan.86@gmail.com>,
	"Valdis Klētnieks" <valdis.kletnieks@vt.edu>
Cc: kernelnewbies@kernelnewbies.org
Subject: Re: Try/catch for modules?
Date: Fri, 18 Oct 2019 17:24:57 -0400	[thread overview]
Message-ID: <c4b7eb94d43a078921a5934229b1eccfe409e28e.camel@surriel.com> (raw)
In-Reply-To: <CAN19L9EF01s_yGwzNLtLp+3HYUxrHrt65XPEd0utvonLZAY8=g@mail.gmail.com>

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On Fri, 2019-10-18 at 12:43 -0300, Martin Galvan wrote:
> El jue., 17 oct. 2019 a las 19:13, Valdis Klētnieks
> (<valdis.kletnieks@vt.edu>) escribió:
> > For starters, the *correct* in-kernel way to deal with this is:
> >         if (!ptr) {
> >                 printk("You blew it!\n");
> >                 goto you_blew_it;
> >         }
> 
> goto statements are harmful. In any case, what I meant was to have
> some sort of safety net to prevent exceptions (i.e. if I screw up and
> forget a NULL check) from panicking the system.

https://koblents.com/Ches/Links/Month-Mar-2013/20-Using-Goto-in-Linux-Kernel-Code/

> > Also, "current PID" and "my module" aren't two things that can
> > correspond....
> 
> I don't understand what you mean by that. Module code (e.g. an ioctl)
> runs as some process. In the case of an ioctl, I'd assume it's the
> same PID of the user process.

Every time you test whether the PID is the PID of the
currently running process, it will be true. Think of
the kernel as a privileged shared library, not as a
program that userspace happens to communicate with.

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