Device Drivers Which Include mkdir("/dev")

[Joel Sherrill]

On Thu, Feb 18, 2021 at 2:08 PM Gedare Bloom <gedare at rtems.org> wrote:

> On Thu, Feb 18, 2021 at 12:52 PM Joel Sherrill <joel at rtems.org> wrote:
> >
> >
> >
> > On Thu, Feb 18, 2021 at 11:52 AM Gedare Bloom <gedare at rtems.org> wrote:
> >>
> >> On Thu, Feb 18, 2021 at 10:20 AM Joel Sherrill <joel at rtems.org> wrote:
> >> >
> >> >
> >> >
> >> > On Thu, Feb 18, 2021 at 11:06 AM Gedare Bloom <gedare at rtems.org>
> wrote:
> >> >>
> >> >> On Thu, Feb 18, 2021 at 8:56 AM Joel Sherrill <joel at rtems.org>
> wrote:
> >> >> >
> >> >> > Hi
> >> >> >
> >> >> > There are a lot of Coverity issues related to device drivers which
> call mkdir("/dev") and ignore the return value. My first thought was that
> they should have (void) added since /dev could have been created by an
> earlier driver.
> >> >> >
> >> >> > Then it occurred to me that libcsupport/src/base_fs.c includes
> mkdir("/dev") and a fatal error if it cannot create it.
> >> >> >
> >> >> > Doesn't this mean that every call to mkdir("/dev") in a BSP or
> device driver is redundant? They should be removed since the base FS
> contents are always in place before any device drivers are called.
> >> >> >
> >> >> > Thoughts?
> >> >> >
> >> >>
> >> >> Seems reasonable. You could probably add an assert that /dev exists.
> >> >
> >> >
> >> > The creation of the device node will fail if /dev does not exist so I
> think that
> >> > is covered.
> >> >
> >> > I think the call is pointless and changing it to stat() to make sure
> it exists
> >> > just adds bulk to the driver/BSP dependencies.
> >> >
> >> > I think just deleting it seems prudent. There is an error path if it
> doesn't
> >> > exist.
> >> >
> >>
> >> ok. I was just suggesting conversion to an assert since that is some
> >> good practice when you have a belief/assumption but aren't totally
> >> convinced. It's fine with me either way. assert(mkdir("/dev") == -1)
> >> or just delete it.
> >
> >
> > Grrr.. I've looked again at the code and it is all Gaisler code doing
> something
> > like mkdir("/dev/leonXXX"). It really could fail. This should be a fatal
> error
> > and would seem to indicate that we need a grlib category of fatal
> BSP/driver
> > errors.
>
> Given the complexity of grlib, that would make some sense. Although
> maybe we can make it a little more generic... FATAL_THIRD_PARTY_DRIVER
> errors might be nicer on them, and can be reused
>

Good suggestion. But I think this particular error is potentially even more
generic.
Any device driver wanting to make a subdirectory /dev/XXX could generate
this.
This seems like the right place to add this but I'm open for better names:

diff --git a/bsps/include/bsp/fatal.h b/bsps/include/bsp/fatal.h
index ec5902755e..0d8507e398 100644
--- a/bsps/include/bsp/fatal.h
+++ b/bsps/include/bsp/fatal.h
@@ -41,6 +41,7 @@ typedef enum {
   BSP_FATAL_CONSOLE_INSTALL_0,
   BSP_FATAL_CONSOLE_INSTALL_1,
   BSP_FATAL_CONSOLE_REGISTER_DEV_2,
+  BSP_FATAL_MAKE_SUBDIR_OF_DEV,

   /* ARM fatal codes */
   BSP_ARM_A9MPCORE_FATAL_CLOCK_IRQ_INSTALL = BSP_FATAL_CODE_BLOCK(1),


>
> >>
> >>
> >> > --joel
> >> >>
> >> >>
> >> >> > --joel
> >> >> > _______________________________________________
> >> >> > devel mailing list
> >> >> > devel at rtems.org
> >> >> > http://lists.rtems.org/mailman/listinfo/devel
>
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