netdev - Re: [PATCH net-next] netdevsim: check return value of debugfs_create

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Date:   Thu, 7 Dec 2017 13:20:53 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     "Prashant Bhole" <bhole_prashant_q7@....ntt.co.jp>
Cc:     "'David S . Miller'" <davem@...emloft.net>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] netdevsim: check return value of
 debugfs_create_dir

On Thu, 7 Dec 2017 17:56:37 +0900, Prashant Bhole wrote:
> > From: Jakub Kicinski [mailto:jakub.kicinski@...ronome.com]
> > 
> > On Thu, 7 Dec 2017 13:10:39 +0900, Prashant Bhole wrote:  
> > > > From: Jakub Kicinski [mailto:jakub.kicinski@...ronome.com]
> > > >
> > > > On Thu,  7 Dec 2017 10:02:13 +0900, Prashant Bhole wrote:  
> > > > > - Handled debugfs_create_dir failure in nsim_init()
> > > > > - Fixed return value of nsim_module_init() when debugfs_create_dir
> > > > > fails
> > > > >
> > > > > Signed-off-by: Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>  
> > > >
> > > > Why?  Failing to expose the state via DebugFS is not fatal to the driver.
> > >
> > > Ok, my intention was to handle the return code properly, which is not
> > > needed as per your comment.
> > > Shall I remove the existing handling in nsim_module_init() in separate
> > > patch?  
> > 
> > I was going back and forth on the error handling quite a bit writing that code.  In
> > the end I decided to leave the module_init check and check for bpf prog
> > directory.  Former one is mostly useful to make sure the is no duplicate directory
> > with the same name, the latter to limit possible false positive in the selftest..
> 
> Ok. Currently return value is checked with IS_ERR(). But when Debug FS is
> enabled, debugfs_create_dir will never return error value. It returns either
> NULL or a valid pointer. Shall I replace IS_ERR with NULL check or
> IS_ERR_OR_NULL check?

Sure.