Re: [PATCH v1 1/1] fs/proc/kcore.c: fix coccinelle reported ERROR instances

[Mirsad Todorovac <mtodorovac69@gmail.com>]

Hi, Mr. Andrew,

On 10/30/24 02:29, Andrew Morton wrote:
> On Tue, 29 Oct 2024 06:46:52 +0100 Mirsad Todorovac <mtodorovac69@gmail.com> wrote:
> 
>> Coccinelle complains about the nested reuse of the pointer `iter' with different
>> pointer type:
>>
>> ./fs/proc/kcore.c:515:26-30: ERROR: invalid reference to the index variable of the iterator on line 499
>> ./fs/proc/kcore.c:534:23-27: ERROR: invalid reference to the index variable of the iterator on line 499
>> ./fs/proc/kcore.c:550:40-44: ERROR: invalid reference to the index variable of the iterator on line 499
>> ./fs/proc/kcore.c:568:27-31: ERROR: invalid reference to the index variable of the iterator on line 499
>> ./fs/proc/kcore.c:581:28-32: ERROR: invalid reference to the index variable of the iterator on line 499
>> ./fs/proc/kcore.c:599:27-31: ERROR: invalid reference to the index variable of the iterator on line 499
>> ./fs/proc/kcore.c:607:38-42: ERROR: invalid reference to the index variable of the iterator on line 499
>> ./fs/proc/kcore.c:614:26-30: ERROR: invalid reference to the index variable of the iterator on line 499
>>
>> Replacing `struct kcore_list *iter' with `struct kcore_list *tmp' doesn't change the
>> scope and the functionality is the same and coccinelle seems happy.
> 
> Well that's dumb of it.  Still, the code is presently a bit weird and
> we don't mind working around such third-party issues.
> 
>> NOTE: There was an issue with using `struct kcore_list *pos' as the nested iterator.
>>       The build did not work!
> 
> It worked for me.  What's wrong with that?

Now with next-20241031 it works for me too:

marvin@defiant:~/linux/kernel/linux-next$ time nice sudo make TARGETS=proc kselftest |& tee ../kself-proc-01a.log; date
make[3]: Entering directory '.../linux-next/tools/testing/selftests/proc'
make[3]: Nothing to be done for 'all'.
make[3]: Leaving directory '.../linux-next/tools/testing/selftests/proc'
make[3]: Entering directory '.../linux-next/tools/testing/selftests/proc'
TAP version 13
1..23
# timeout set to 45
# selftests: proc: fd-001-lookup
ok 1 selftests: proc: fd-001-lookup
# timeout set to 45
# selftests: proc: fd-002-posix-eq
ok 2 selftests: proc: fd-002-posix-eq
# timeout set to 45
# selftests: proc: fd-003-kthread
ok 3 selftests: proc: fd-003-kthread
# timeout set to 45
# selftests: proc: proc-2-is-kthread
ok 4 selftests: proc: proc-2-is-kthread
# timeout set to 45
# selftests: proc: proc-loadavg-001
ok 5 selftests: proc: proc-loadavg-001
# timeout set to 45
# selftests: proc: proc-empty-vm
ok 6 selftests: proc: proc-empty-vm
# timeout set to 45
# selftests: proc: proc-pid-vm
ok 7 selftests: proc: proc-pid-vm
# timeout set to 45
# selftests: proc: proc-self-map-files-001
ok 8 selftests: proc: proc-self-map-files-001
# timeout set to 45
# selftests: proc: proc-self-map-files-002
ok 9 selftests: proc: proc-self-map-files-002
# timeout set to 45
# selftests: proc: proc-self-isnt-kthread
ok 10 selftests: proc: proc-self-isnt-kthread
# timeout set to 45
# selftests: proc: proc-self-syscall
ok 11 selftests: proc: proc-self-syscall
# timeout set to 45
# selftests: proc: proc-self-wchan
ok 12 selftests: proc: proc-self-wchan
# timeout set to 45
# selftests: proc: proc-subset-pid
ok 13 selftests: proc: proc-subset-pid
# timeout set to 45
# selftests: proc: proc-tid0
ok 14 selftests: proc: proc-tid0
# timeout set to 45
# selftests: proc: proc-uptime-001
ok 15 selftests: proc: proc-uptime-001
# timeout set to 45
# selftests: proc: proc-uptime-002
ok 16 selftests: proc: proc-uptime-002
# timeout set to 45
# selftests: proc: read
ok 17 selftests: proc: read
# timeout set to 45
# selftests: proc: self
ok 18 selftests: proc: self
# timeout set to 45
# selftests: proc: setns-dcache
ok 19 selftests: proc: setns-dcache
# timeout set to 45
# selftests: proc: setns-sysvipc
ok 20 selftests: proc: setns-sysvipc
# timeout set to 45
# selftests: proc: thread-self
ok 21 selftests: proc: thread-self
# timeout set to 45
# selftests: proc: proc-multiple-procfs
ok 22 selftests: proc: proc-multiple-procfs
# timeout set to 45
# selftests: proc: proc-fsconfig-hidepid
ok 23 selftests: proc: proc-fsconfig-hidepid
make[3]: Leaving directory '.../linux-next/tools/testing/selftests/proc'

Unless I badly missed something, the build is OK.

>> --- a/fs/proc/kcore.c
>> +++ b/fs/proc/kcore.c
>> @@ -493,13 +493,13 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
>>  		 * the previous entry, search for a matching entry.
>>  		 */
>>  		if (!m || start < m->addr || start >= m->addr + m->size) {
>> -			struct kcore_list *iter;
>> +			struct kcore_list *tmp;
> 
> `tmp' is a really poor identifier :(
> 
> Let's try `pos':
> 
> --- a/fs/proc/kcore.c~fs-proc-kcorec-fix-coccinelle-reported-error-instances-fix
> +++ a/fs/proc/kcore.c
> @@ -493,13 +493,13 @@ static ssize_t read_kcore_iter(struct ki
>  		 * the previous entry, search for a matching entry.
>  		 */
>  		if (!m || start < m->addr || start >= m->addr + m->size) {
> -			struct kcore_list *tmp;
> +			struct kcore_list *pos;
>  
>  			m = NULL;
> -			list_for_each_entry(tmp, &kclist_head, list) {
> -				if (start >= tmp->addr &&
> -				    start < tmp->addr + tmp->size) {
> -					m = tmp;
> +			list_for_each_entry(pos, &kclist_head, list) {
> +				if (start >= pos->addr &&
> +				    start < pos->addr + pos->size) {
> +					m = pos;
>  					break;
>  				}
>  			}



I see that it is already applied in next-20241031 and it is just running.

$ uname -rms
Linux 6.12.0-rc5-next-20241031nxt x86_64

Please add

Tested-by: Mirsad Todorovac <mtodorovac69@gmail.com>

Thanks.

Best regards,
Mirsad