Re: [PATCH v4 03/19] powerpc: Mark variable `l` as unused, remove `path`

[christophe leroy]

Le 06/04/2018 Ã 20:32, Mathieu Malaterre a ÃcritÂ:
> On Fri, Apr 6, 2018 at 5:33 PM, LEROY Christophe
> <christophe.leroy@xxxxxx> wrote:
> > Mathieu Malaterre <malat@xxxxxxxxxx> a Ãcrit :
> >
> > > Add gcc attribute unused for `l` variable, replace `path` variable
> > > directly
> > > with prom_scratch. Fix warnings treated as errors with W=1:
> > >
> > >    arch/powerpc/kernel/prom_init.c:607:6: error: variable âlâ set but not
> > > used [-Werror=unused-but-set-variable]
> > >    arch/powerpc/kernel/prom_init.c:1388:8: error: variable âpathâ set but
> > > not used [-Werror=unused-but-set-variable]
> > >
> > > Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > > Signed-off-by: Mathieu Malaterre <malat@xxxxxxxxxx>
> > > ---
> > > v4: redo v3 since path variable can be avoided
> > > v3: really move path within ifdef DEBUG_PROM
> > > v2: move path within ifdef DEBUG_PROM
> > >
> > >   arch/powerpc/kernel/prom_init.c | 11 +++++------
> > >   1 file changed, 5 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/arch/powerpc/kernel/prom_init.c
> > > b/arch/powerpc/kernel/prom_init.c
> > > index f8a9a50ff9b5..4b223a9470be 100644
> > > --- a/arch/powerpc/kernel/prom_init.c
> > > +++ b/arch/powerpc/kernel/prom_init.c
> > > @@ -604,7 +604,7 @@ static void __init early_cmdline_parse(void)
> > >          const char *opt;
> > >
> > >          char *p;
> > > -       int l = 0;
> > > +       int l __maybe_unused = 0;
> >
> >
> > Instead of hiding the problem with __maybe_unused, I think we could replace
> > the
> > #ifdef CONFIG_CMDLINE
> > by a
> > if (IS_ENABLED(CONFIG_CMDLINE_BOOL))
> >
> > This is recommanded by Linux codying style
>
> Neat. I was not aware of this trick. Does not work in this case though:
>
> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> index 7925f64fefde..19634739b279 100644
> --- a/arch/powerpc/kernel/prom_init.c
> +++ b/arch/powerpc/kernel/prom_init.c
> @@ -604,17 +604,16 @@ static void __init early_cmdline_parse(void)
>          const char *opt;
>
>          char *p;
> -       int l __maybe_unused = 0;
> +       int l = 0;
>
>          prom_cmd_line[0] = 0;
>          p = prom_cmd_line;
>          if ((long)prom.chosen > 0)
>                  l = prom_getprop(prom.chosen, "bootargs", p,
> COMMAND_LINE_SIZE-1);
> -#ifdef CONFIG_CMDLINE
> -       if (l <= 0 || p[0] == '\0') /* dbl check */
> -               strlcpy(prom_cmd_line,
> -                       CONFIG_CMDLINE, sizeof(prom_cmd_line));
> -#endif /* CONFIG_CMDLINE */
> +       if (IS_ENABLED(CONFIG_CMDLINE_BOOL))
> +               if (l <= 0 || p[0] == '\0') /* dbl check */
> +                       strlcpy(prom_cmd_line,
> +                               CONFIG_CMDLINE, sizeof(prom_cmd_line));
>          prom_printf("command line: %s\n", prom_cmd_line);
>
>   #ifdef CONFIG_PPC64
>
>
> leads to:
>
>    CC      arch/powerpc/kernel/prom_init.o
> ../arch/powerpc/kernel/prom_init.c: In function âearly_cmdline_parseâ:
> ../arch/powerpc/kernel/prom_init.c:616:5: error: âCONFIG_CMDLINEâ
> undeclared (first use in this function)
>       CONFIG_CMDLINE, sizeof(prom_cmd_line));
>       ^~~~~~~~~~~~~~
> ../arch/powerpc/kernel/prom_init.c:616:5: note: each undeclared
> identifier is reported only once for each function it appears in
> ../scripts/Makefile.build:312: recipe for target
> 'arch/powerpc/kernel/prom_init.o' failed
> make[6]: *** [arch/powerpc/kernel/prom_init.o] Error 1

And what about something like :


+       if (l <= 0 || p[0] == '\0') { /* dbl check */
 #ifdef CONFIG_CMDLINE
-       if (l <= 0 || p[0] == '\0') /* dbl check */
                strlcpy(prom_cmd_line,
                        CONFIG_CMDLINE, sizeof(prom_cmd_line));
 #endif /* CONFIG_CMDLINE */
+}
         prom_printf("command line: %s\n", prom_cmd_line);

Christophe


> > Christophe
> >
> >
> > >          prom_cmd_line[0] = 0;
> > >          p = prom_cmd_line;
> > > @@ -1386,7 +1386,7 @@ static void __init reserve_mem(u64 base, u64 size)
> > >   static void __init prom_init_mem(void)
> > >   {
> > >          phandle node;
> > > -       char *path, type[64];
> > > +       char type[64];
> > >          unsigned int plen;
> > >          cell_t *p, *endp;
> > >          __be32 val;
> > > @@ -1407,7 +1407,6 @@ static void __init prom_init_mem(void)
> > >          prom_debug("root_size_cells: %x\n", rsc);
> > >
> > >          prom_debug("scanning memory:\n");
> > > -       path = prom_scratch;
> > >
> > >          for (node = 0; prom_next_node(&node); ) {
> > >                  type[0] = 0;
> > > @@ -1432,9 +1431,9 @@ static void __init prom_init_mem(void)
> > >                  endp = p + (plen / sizeof(cell_t));
> > >
> > >   #ifdef DEBUG_PROM
> > > -               memset(path, 0, PROM_SCRATCH_SIZE);
> > > -               call_prom("package-to-path", 3, 1, node, path,
> > > PROM_SCRATCH_SIZE-1);
> > > -               prom_debug("  node %s :\n", path);
> > > +               memset(prom_scratch, 0, PROM_SCRATCH_SIZE);
> > > +               call_prom("package-to-path", 3, 1, node, prom_scratch,
> > > PROM_SCRATCH_SIZE - 1);
> > > +               prom_debug("  node %s :\n", prom_scratch);
> > >   #endif /* DEBUG_PROM */
> > >
> > >                  while ((endp - p) >= (rac + rsc)) {
> > > --
> > > 2.11.0

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