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Message-ID: <ff779a22-0bbb-4885-5678-1371d749bc88@c-s.fr>
Date: Tue, 24 Apr 2018 21:20:29 +0200
From: christophe leroy <christophe.leroy@....fr>
To: Mathieu Malaterre <malat@...ian.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
Paul Mackerras <paulus@...ba.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH v4 03/19] powerpc: Mark variable `l` as unused, remove
`path`
Le 06/04/2018 à 20:32, Mathieu Malaterre a écrit :
> On Fri, Apr 6, 2018 at 5:33 PM, LEROY Christophe
> <christophe.leroy@....fr> wrote:
>> Mathieu Malaterre <malat@...ian.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 <mpe@...erman.id.au>
>>> Signed-off-by: Mathieu Malaterre <malat@...ian.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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