linux-kernel - Re: [PATCH] Removed unused variable

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Message-ID: <aTqJI8CGTOkzNE2A@google.com>
Date: Thu, 11 Dec 2025 17:04:35 +0800
From: Kuan-Wei Chiu <visitorckw@...il.com>
To: Pycode <pycode42@...il.com>
Cc: Jeff Layton <jlayton@...nel.org>, Trond Myklebust <trondmy@...nel.org>,
	Anna Schumaker <anna@...nel.org>, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Removed unused variable

On Thu, Dec 11, 2025 at 08:31:57AM +0100, Pycode wrote:
> On Thu, Dec 11, 2025 at 02:54:03PM +0800, Kuan-Wei Chiu wrote:
> > On Thu, Dec 11, 2025 at 06:57:54AM +0100, Pycode wrote:
> > > On Thu, Dec 11, 2025 at 08:10:25AM +0900, Jeff Layton wrote:
> > > > A more descriptive title is preferred: "Remove unused variable from
> > > > nfs4_ff_alloc_deviceid_node()"
> > > > 
> > > 
> > > Thanks for the advices!
> > > 
> > > > On Wed, 2025-12-10 at 21:59 +0100, Pycode wrote:
> > > > > Signed-off-by: Pycode <pycode42@...il.com>
> > > > > 
> > > > > Removed the unused variable ret in
> > > > > fs/nfs/flexfilelayout/flexfilelayoutdev.c
> > > > > 
> > > > > (Disclaimer this is my first patch, be sorry if I have done anything
> > > > > wrong!)
> > > > > ---
> > > > >  fs/nfs/flexfilelayout/flexfilelayoutdev.c | 4 +---
> > > > >  1 file changed, 1 insertion(+), 3 deletions(-)
> > > > > 
> > > > > diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
> > > > > index c55ea8fa3bfa..9cd04e85d52f 100644
> > > > > --- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
> > > > > +++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
> > > > > @@ -53,7 +53,7 @@ nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
> > > > >  	u32 mp_count;
> > > > >  	u32 version_count;
> > > > >  	__be32 *p;
> > > > > -	int i, ret = -ENOMEM;
> > > > > +	int i = -ENOMEM;
> > > > >  
> > > > 
> > > > No need to initialize this.
> > > > 
> > > > >  	/* set up xdr stream */
> > > > >  	scratch = folio_alloc(gfp_flags, 0);
> > > > > @@ -88,7 +88,6 @@ nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
> > > > >  	if (list_empty(&dsaddrs)) {
> > > > >  		dprintk("%s: no suitable DS addresses found\n",
> > > > >  			__func__);
> > > > > -		ret = -ENOMEDIUM;
> > > > >  		goto out_err_drain_dsaddrs;
> > > > >  	}
> > > > >  
> > > > > @@ -134,7 +133,6 @@ nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
> > > > >  			dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
> > > > >  				i, ds_versions[i].version,
> > > > >  				ds_versions[i].minor_version);
> > > > > -			ret = -EPROTONOSUPPORT;
> > > > >  			goto out_err_drain_dsaddrs;
> > > > >  		}
> > > > >  
> > > > 
> > > > What about the dprintk() at the bottom of this function? Does this
> > > > actually build?
> > > 
> > > There is no dprintk() at the bottom that used the variable.
> > 
> > At the bottom of this function, there is a dprintk call that refers to ret:
> > 
> > 	dprintk("%s ERROR: returning %d\n", __func__, ret);
> > 	return NULL;
> > 
> > This causes the build to fail:
> > 
> > In file included from ./include/asm-generic/bug.h:31,
> >                  from ./arch/x86/include/asm/bug.h:193,
> >                  from ./arch/x86/include/asm/alternative.h:9,
> >                  from ./arch/x86/include/asm/barrier.h:5,
> >                  from ./include/asm-generic/bitops/generic-non-atomic.h:7,
> >                  from ./include/linux/bitops.h:28,
> >                  from ./include/linux/kernel.h:23,
> >                  from ./include/linux/uio.h:8,
> >                  from ./include/linux/socket.h:8,
> >                  from ./include/uapi/linux/in.h:25,
> >                  from ./include/linux/in.h:19,
> >                  from ./include/linux/nfs_fs.h:22,
> >                  from fs/nfs/flexfilelayout/flexfilelayoutdev.c:10:
> > fs/nfs/flexfilelayout/flexfilelayoutdev.c: In function ‘nfs4_ff_alloc_deviceid_node’:
> > fs/nfs/flexfilelayout/flexfilelayoutdev.c:182:55: error: ‘ret’ undeclared (first use in this function); did you mean ‘net’?
> >   182 |         dprintk("%s ERROR: returning %d\n", __func__, ret);
> >       |                                                       ^~~
> > ./include/linux/printk.h:484:33: note: in definition of macro ‘printk_index_wrap’
> >   484 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
> >       |                                 ^~~~~~~~~~~
> > ./include/linux/sunrpc/debug.h:36:41: note: in expansion of macro ‘printk’
> >    36 | #  define __sunrpc_printk(fmt, ...)     printk(KERN_DEFAULT fmt, ##__VA_ARGS__)
> >       |                                         ^~~~~~
> > ./include/linux/sunrpc/debug.h:42:17: note: in expansion of macro ‘__sunrpc_printk’
> >    42 |                 __sunrpc_printk(fmt, ##__VA_ARGS__);                    \
> >       |                 ^~~~~~~~~~~~~~~
> > ./include/linux/sunrpc/debug.h:25:9: note: in expansion of macro ‘dfprintk’
> >    25 |         dfprintk(FACILITY, fmt, ##__VA_ARGS__)
> >       |         ^~~~~~~~
> > fs/nfs/flexfilelayout/flexfilelayoutdev.c:182:9: note: in expansion of macro ‘dprintk’
> >   182 |         dprintk("%s ERROR: returning %d\n", __func__, ret);
> >       |         ^~~~~~~
> > fs/nfs/flexfilelayout/flexfilelayoutdev.c:182:55: note: each undeclared identifier is reported only once for each function it appears in
> >   182 |         dprintk("%s ERROR: returning %d\n", __func__, ret);
> >       |                                                       ^~~
> > ./include/linux/printk.h:484:33: note: in definition of macro ‘printk_index_wrap’
> >   484 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
> >       |                                 ^~~~~~~~~~~
> > ./include/linux/sunrpc/debug.h:36:41: note: in expansion of macro ‘printk’
> >    36 | #  define __sunrpc_printk(fmt, ...)     printk(KERN_DEFAULT fmt, ##__VA_ARGS__)
> >       |                                         ^~~~~~
> > ./include/linux/sunrpc/debug.h:42:17: note: in expansion of macro ‘__sunrpc_printk’
> >    42 |                 __sunrpc_printk(fmt, ##__VA_ARGS__);                    \
> >       |                 ^~~~~~~~~~~~~~~
> > ./include/linux/sunrpc/debug.h:25:9: note: in expansion of macro ‘dfprintk’
> >    25 |         dfprintk(FACILITY, fmt, ##__VA_ARGS__)
> >       |         ^~~~~~~~
> > fs/nfs/flexfilelayout/flexfilelayoutdev.c:182:9: note: in expansion of macro ‘dprintk’
> >   182 |         dprintk("%s ERROR: returning %d\n", __func__, ret);
> >       |         ^~~~~~~
> > make[5]: *** [scripts/Makefile.build:287: fs/nfs/flexfilelayout/flexfilelayoutdev.o] Error 1
> > make[4]: *** [scripts/Makefile.build:556: fs/nfs/flexfilelayout] Error 2
> > make[3]: *** [scripts/Makefile.build:556: fs/nfs] Error 2
> > make[2]: *** [scripts/Makefile.build:556: fs] Error 2
> 
> Sorry, I didn't see that there were more returns because of the jumps. For some reason, it compiled without any problems for me.
> 
>
My guess is that this build failure only shows up with the debug config
on, which you don't seem to have enabled.

Regards,
Kuan-Wei