crash_dump: Remove redundant less-than-zero check

[PATCH] crash_dump: Remove redundant less-than-zero check

Posted by Thorsten Blum 1 month, 2 weeks ago

'key_count' is an 'unsigned int' and cannot be less than zero. Remove
the redundant condition.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 kernel/crash_dump_dm_crypt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
index 1f4067fbdb94..27a144920562 100644
--- a/kernel/crash_dump_dm_crypt.c
+++ b/kernel/crash_dump_dm_crypt.c
@@ -115,7 +115,7 @@ static int restore_dm_crypt_keys_to_thread_keyring(void)
 
 	addr = dm_crypt_keys_addr;
 	dm_crypt_keys_read((char *)&key_count, sizeof(key_count), &addr);
-	if (key_count < 0 || key_count > KEY_NUM_MAX) {
+	if (key_count > KEY_NUM_MAX) {
 		kexec_dprintk("Failed to read the number of dm-crypt keys\n");
 		return -1;
 	}
-- 
Thorsten Blum <thorsten.blum@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4

Re: [PATCH] crash_dump: Remove redundant less-than-zero check

Posted by Andrew Morton 1 month, 2 weeks ago

On Sat, 28 Feb 2026 09:51:36 +0100 Thorsten Blum <thorsten.blum@linux.dev> wrote:

> 'key_count' is an 'unsigned int' and cannot be less than zero. Remove
> the redundant condition.
> 

umm. OK.

> --- a/kernel/crash_dump_dm_crypt.c
> +++ b/kernel/crash_dump_dm_crypt.c
> @@ -115,7 +115,7 @@ static int restore_dm_crypt_keys_to_thread_keyring(void)
>  
>  	addr = dm_crypt_keys_addr;
>  	dm_crypt_keys_read((char *)&key_count, sizeof(key_count), &addr);
> -	if (key_count < 0 || key_count > KEY_NUM_MAX) {
> +	if (key_count > KEY_NUM_MAX) {
>  		kexec_dprintk("Failed to read the number of dm-crypt keys\n");
>  		return -1;
>  	}

iirc Linus has said "this is OK".  The compiler will eliminate it and
the code still works if the type is later changed to signed.