On Tue, 29 Mar 2022 at 08:31, Manivannan Sadhasivam
<manivannan.sadhasivam@xxxxxxxxxx> wrote:
>
> Hi Mathieu,
>
> On Mon, Mar 28, 2022 at 09:51:23AM -0600, Mathieu Poirier wrote:
> > Hi Mani,
> >
> > On Thu, Mar 24, 2022 at 11:42:24PM +0530, Manivannan Sadhasivam wrote:
> > > DebugFS APIs are designed to return only the error pointers and not NULL
> > > in the case of failure. So these return pointers are safe to be passed on
> > > to the successive debugfs_create* APIs.
> > >
> > > Therefore, let's just get rid of the checks.
> > >
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> > > ---
> > > drivers/remoteproc/remoteproc_debugfs.c | 17 ++---------------
> > > 1 file changed, 2 insertions(+), 15 deletions(-)
> > >
> > > diff --git a/drivers/remoteproc/remoteproc_debugfs.c b/drivers/remoteproc/remoteproc_debugfs.c
> > > index b5a1e3b697d9..2e2c4a31c154 100644
> > > --- a/drivers/remoteproc/remoteproc_debugfs.c
> > > +++ b/drivers/remoteproc/remoteproc_debugfs.c
> > > @@ -386,16 +386,8 @@ void rproc_remove_trace_file(struct dentry *tfile)
> > > struct dentry *rproc_create_trace_file(const char *name, struct rproc *rproc,
> > > struct rproc_debug_trace *trace)
> > > {
> > > - struct dentry *tfile;
> > > -
> > > - tfile = debugfs_create_file(name, 0400, rproc->dbg_dir, trace,
> > > + return debugfs_create_file(name, 0400, rproc->dbg_dir, trace,
> > > &trace_rproc_ops);
> > > - if (!tfile) {
> > > - dev_err(&rproc->dev, "failed to create debugfs trace entry\n");
> > > - return NULL;
> > > - }
> > > -
> > > - return tfile;
> >
> > Please see this thread [1] for an earlier conversation on this topic.
> >
> > [1]. https://lore.kernel.org/lkml/20220105131022.25247-1-linmq006@xxxxxxxxx/T/
> >
>
> Thanks for the pointer! I believe the conclusion was to return 0 here
> and ignore the return from debugfs_create_file(). If that's the case, it looks
> fine to me and I'll send a follow-up patch.
Correct.
>
> > > }
> > >
> > > void rproc_delete_debug_dir(struct rproc *rproc)
> > > @@ -411,8 +403,6 @@ void rproc_create_debug_dir(struct rproc *rproc)
> > > return;
> > >
> > > rproc->dbg_dir = debugfs_create_dir(dev_name(dev), rproc_dbg);
> > > - if (!rproc->dbg_dir)
> > > - return;
> > >
> > > debugfs_create_file("name", 0400, rproc->dbg_dir,
> > > rproc, &rproc_name_ops);
> > > @@ -430,11 +420,8 @@ void rproc_create_debug_dir(struct rproc *rproc)
> > >
> > > void __init rproc_init_debugfs(void)
> > > {
> > > - if (debugfs_initialized()) {
> > > + if (debugfs_initialized())
> > > rproc_dbg = debugfs_create_dir(KBUILD_MODNAME, NULL);
> > > - if (!rproc_dbg)
> > > - pr_err("can't create debugfs dir\n");
> > > - }
> >
> > The above two are fine since debugfs_create_file() and debugfs_create_dir() can
> > deal with @parent being an error code.
> >
>
> debugfs_create_* APIs would never return NULL, so these checks are wrong.
> Moreover, Greg recommends not to check the return value for any of these
> functions.
>
When writing "the above two are fine", I meant that I am in agreement
with your changes. Reading my comment again I can see how it could be
interpreted as "I don't think your changes are necessary", which isn't
the case.
> I've found the mail thread where Greg explained the reasoning behind it:
> https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1907800.html
>
I'll bookmark this one as it is bound to come back again.
> Thanks,
> Mani
>
> > Thanks,
> > Mathieu
> >
> > > }
> > >
> > > void __exit rproc_exit_debugfs(void)
> > > --
> > > 2.25.1
> > >
