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

[christophe leroy]

Le 06/04/2018 à 20:32, Mathieu Malaterre a écrit :

On Fri, Apr 6, 2018 at 5:33 PM, LEROY Christophe
<christophe.le...@c-s.fr> wrote:

Mathieu Malaterre <ma...@debian.org> a écrit :

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 ‘l’ set but not
used [-Werror=unused-but-set-variable]
   arch/powerpc/kernel/prom_init.c:1388:8: error: variable ‘path’ set but
not used [-Werror=unused-but-set-variable]

Suggested-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Mathieu Malaterre <ma...@debian.org>
---
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 ‘early_cmdline_parse’:
../arch/powerpc/kernel/prom_init.c:616:5: error: ‘CONFIG_CMDLINE’
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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