linux-kernel - Re: [PATCH] staging: axis-fifo: initialize timeouts in probe only

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Message-ID: <20230315150656.GA2938956@dev-arch.thelio-3990X>
Date:   Wed, 15 Mar 2023 08:06:56 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Khadija Kamran <kamrankhadijadj@...il.com>
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Alison Schofield <alison.schofield@...el.com>,
        outreachy@...ts.linux.dev,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: axis-fifo: initialize timeouts in probe only

Hi Khadija,

On Wed, Mar 15, 2023 at 07:22:39PM +0500, Khadija Kamran wrote:
> On Wed, Mar 15, 2023 at 02:34:31PM +0100, Fabio M. De Francesco wrote:
> > Aside from what I said and asked for with the other message of this same 
> > thread, please take note that you can build a specific module if you prefer 
> > not to re-build the whole kernel and other modules at the same time. 
> > 
> > I'm pretty sure that the instructions to do so are in the OutreachyFirstPatch 
> > tutorial.
> > 
> > If they are not there, please let us know.
> > 
> > Fabio
> 
> Hey Fabio!
> 
> In the Outreachy FirstPatchTutorial under the 'Compiling only part of
> the kernel' section there are ways to compile only some part of the
> kernel.
> 
> I have tried using "make W=1 drivers/staging/axis-fifo/" and it says
> 'nothing to be done for'. 

Is CONFIG_XIL_AXIS_FIFO enabled in your configuration?

> Should I start with the steps to reproduce? :'(

I did see a report of this same warning occurring with GCC but the
report I commented on cane from clang/LLVM; using that toolchain may
make it easier for you to reproduce this issue. The robot's reproduction
instructions are fine but I think doing it manually is actually simpler.

Ubuntu 22.04 should have a pretty modern version of clang/LLVM, which
you can install via 'sudo apt install clang lld llvm'.
https://apt.llvm.org is another resource.

First, we will grab the configuration that was provided in the report:

$ wget -O .config https://download.01.org/0day-ci/archive/20230314/202303141159.6wN9HNP9-lkp@intel.com/config

Next, we want to make sure the configuration is synced, since we are
technically changing compilers:

$ make -j"$(nproc)" ARCH=arm64 LLVM=1 olddefconfig

Finally, you should be able to build that object file and see the
warning:

$ make -j"$(nproc)" ARCH=arm64 LLVM=1 drivers/staging/axis-fifo/
...
drivers/staging/axis-fifo/axis-fifo.c:817:18: warning: implicit conversion from 'long' to 'int' changes value from 9223372036854775807 to -1 [-Wconstant-conversion]
                read_timeout = MAX_SCHEDULE_TIMEOUT;
                             ~ ^~~~~~~~~~~~~~~~~~~~
./include/linux/sched.h:296:31: note: expanded from macro 'MAX_SCHEDULE_TIMEOUT'
#define MAX_SCHEDULE_TIMEOUT            LONG_MAX
                                        ^~~~~~~~
./include/vdso/limits.h:11:19: note: expanded from macro 'LONG_MAX'
#define LONG_MAX        ((long)(~0UL >> 1))
                         ^~~~~~~~~~~~~~~~~
drivers/staging/axis-fifo/axis-fifo.c:822:19: warning: implicit conversion from 'long' to 'int' changes value from 9223372036854775807 to -1 [-Wconstant-conversion]
                write_timeout = MAX_SCHEDULE_TIMEOUT;
                              ~ ^~~~~~~~~~~~~~~~~~~~
./include/linux/sched.h:296:31: note: expanded from macro 'MAX_SCHEDULE_TIMEOUT'
#define MAX_SCHEDULE_TIMEOUT            LONG_MAX
                                        ^~~~~~~~
./include/vdso/limits.h:11:19: note: expanded from macro 'LONG_MAX'
#define LONG_MAX        ((long)(~0UL >> 1))
                         ^~~~~~~~~~~~~~~~~
2 warnings generated.

Just repeat the last step as you investigate. If you have any further
issues or questions, please let me know. For the record, I am not
associated with Outreachy (I am one of the maintainers of clang/LLVM
support in the kernel), so if I have messed something up or overstepped
some boundary, I do apologize.

Cheers,
Nathan