On 09/12/2017 09:39 PM, jianchao.wang wrote: >> Exactly, and especially the readability is the key element here. It's >> just not worth it to try and be too clever, especially not for >> something like this. When you read the above, you immediately know >> what the code does without needing a comment. That's not true for the >> other construct. You both have to read other parts of the function >> to figure out what it does, AND read the entire function to ensure it >> always does the right thing. Fragile. > > Thanks for your comments , jens and ming. I＇m really appreciative of > that. About the fragility, do you mean the possibility that may > release the tag of the next rq which has a driver tag itself (maybe a > flush) ? I mean that if you do: if (!list_empty(list)) blk_mq_put_driver_tag(nxt); it's fragile code in the sense that changes elsewhere in the function are harder to validate and/or can impact the functionality of that simple if and tag put. The actual release must always be safe, of course. -- Jens Axboe
