Messages in this thread | | | Subject | Re: [PATCH] blk-mq: put the driver tag of nxt rq before first one is requeued | From | Jens Axboe <> | Date | Tue, 12 Sep 2017 21:54:06 -0600 |
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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
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