Re: [PATCH 3/7] lib/iov_iter: fix misplaced parenthesis in iov_iter_restore() kvec check

[Josh Law]

On 23 March 2026 12:39:10 GMT, Christian Brauner <brauner@xxxxxxxxxx> wrote:
>On Fri, Mar 13, 2026 at 06:10:34PM +0000, Josh Law wrote:
>> When restoring a kvec-backed iterator after a short write in a kernel
>> socket sendmsg path (e.g. an NFS client resending an RPC call), the
>> WARN_ON_ONCE guard fires a spurious warning on every first call.
>> 
>> The closing parenthesis of WARN_ON_ONCE is after !iter_is_ubuf(i),
>> leaving !iov_iter_is_kvec(i) as a separate && operand outside the
>> macro:
>> 
>>   WARN_ON_ONCE(!bvec && !iovec && !ubuf) && !kvec
>> 
>> For kvec iterators this evaluates as WARN_ON_ONCE(true) && false — the
>> warning fires but the return is skipped, so execution proceeds correctly.
>> The warning is the only visible symptom, but it is confusing and may
>> mask real issues.
>> 
>> Found through code review of the operator precedence in the condition
>> expression and confirmed by tracing the macro expansion.
>> 
>> Move the closing parenthesis to include the kvec check inside
>> WARN_ON_ONCE so the warning only fires for genuinely unsupported
>> iterator types.
>> 
>> Signed-off-by: Josh Law <objecting@xxxxxxxxxxxxx>
>> ---
>>  lib/iov_iter.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
>> index 325669b103ed..6a7959bfc849 100644
>> --- a/lib/iov_iter.c
>> +++ b/lib/iov_iter.c
>> @@ -1471,7 +1471,7 @@ EXPORT_SYMBOL_GPL(import_ubuf);
>>  void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
>>  {
>>  	if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i) &&
>> -			 !iter_is_ubuf(i)) && !iov_iter_is_kvec(i))
>> +			 !iter_is_ubuf(i) && !iov_iter_is_kvec(i)))
>>  		return;
>>  	i->iov_offset = state->iov_offset;
>>  	i->count = state->count;
>
>Look... the placement is intentional as is easily identifiable by
>looking at the history of the commits. This clearly is AI generated
>and you don't have the capacity at the moment to meaningfully argue or
>present the technical changes you are proposing - if you are an actual
>person at all. As such I see no reason to engage with this.



1: i am a real human
2: For code written by AI, i use Assisted-by: , i wrote the commit description with ai (thats why its so long)


Sorry for wasting your time

V/R


Josh Law