linux-kernel - Re: [PATCH] Fix implicit cast warning in test_klp

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Date: Tue, 20 Feb 2024 14:06:10 +0800
From: zhang warden <zhangwarden@...il.com>
To: Marcos Paulo de Souza <mpdesouza@...e.com>
Cc: Shresth Prasad <shresthprasad7@...il.com>,
 jpoimboe@...nel.org,
 jikos@...nel.org,
 mbenes@...e.cz,
 pmladek@...e.com,
 joe.lawrence@...hat.com,
 shuah@...nel.org,
 live-patching@...r.kernel.org,
 linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 linux-kernel-mentees@...ts.linuxfoundation.org,
 skhan@...uxfoundation.org
Subject: Re: [PATCH]     Fix implicit cast warning in test_klp_state.c

Well, the repo location I use is git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git.
It seem klp_get_state return struct klp_state.
The definition of this function in my repo as follows:

struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id) 
{
    struct klp_state *state;

    klp_for_each_state(patch, state) {
        if (state->id == id) 
            return state;
    }   

    return NULL;
}
EXPORT_SYMBOL_GPL(klp_get_state);

Are you sure there is really a need for forced conversion?

> 2024年2月19日 22:16，Marcos Paulo de Souza <mpdesouza@...e.com> 写道：
> 
> On Sat, 17 Feb 2024 04:21:26 +0530 Shresth Prasad <shresthprasad7@...il.com> wrote:
> 
>>    The function `klp_get_state` returns an `int` value, but the variable
>>    `loglevel_state` is of type `struct klp_state *` and thus does an
>>    implicit cast. Explicitly casting these values fixes:
>> 
>>            - warning: assignment to \u2018struct klp_state *\u2019 from \u2018int\u2019
>>    makes pointer from integer without a cast [-Wint-conversion]
>> 
>>    on lines 38, 55, 68 and 80 of test_klp_state.c
> 
> I was unable to find where you saw the klp_get_state returning int. I tried
> searching at the current master of live-patching repo[1], on linux-next. Can
> you point where do you saw it? For me, klp_get_state return a pointer to klp_state.
> 
> Thanks,
>  Marcos
> 
> [1]: https://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching.git/tree/kernel/livepatch/state.c
> 
>> 
>> Signed-off-by: Shresth Prasad <shresthprasad7@...il.com>
>> ---
>> .../selftests/livepatch/test_modules/test_klp_state.c     | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
>> index 57a4253acb01..ae6b1ca15fc0 100644
>> --- a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
>> +++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
>> @@ -35,7 +35,7 @@ static int allocate_loglevel_state(void)
>> {
>> struct klp_state *loglevel_state;
>> 
>> - loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> + loglevel_state = (struct klp_state *)klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> if (!loglevel_state)
>> return -EINVAL;
>> 
>> @@ -52,7 +52,7 @@ static void fix_console_loglevel(void)
>> {
>> struct klp_state *loglevel_state;
>> 
>> - loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> + loglevel_state = (struct klp_state *)klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> if (!loglevel_state)
>> return;
>> 
>> @@ -65,7 +65,7 @@ static void restore_console_loglevel(void)
>> {
>> struct klp_state *loglevel_state;
>> 
>> - loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> + loglevel_state = (struct klp_state *)klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> if (!loglevel_state)
>> return;
>> 
>> @@ -77,7 +77,7 @@ static void free_loglevel_state(void)
>> {
>> struct klp_state *loglevel_state;
>> 
>> - loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> + loglevel_state = (struct klp_state *)klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
>> if (!loglevel_state)
>> return;
>> 
>> -- 
>> 2.43.1
>