Messages in this thread | | | Date | Fri, 9 Dec 2011 12:48:16 -0200 | From | Glauber Costa <> | Subject | Re: [PATCH v8 1/9] Basic kernel memory functionality for the Memory Controller |
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On 12/09/2011 12:44 PM, David Laight wrote: > >> How about this? >> >> val = !!val; >> >> /* >> * This follows the same hierarchy restrictions than >> * mem_cgroup_hierarchy_write() >> */ >> if (!parent || !parent->use_hierarchy) { >> if (list_empty(&cgroup->children)) >> memcg->kmem_independent_accounting = val; >> else >> return -EBUSY; >> } >> else >> return -EINVAL; >> >> return 0; > > Inverting the tests gives easier to read code: > > if (parent&& parent->user_hierarchy) > return -EINVAL; > if (!list_empty(&cgroup->children)) > return -EBUSY; > memcg->kmem_independent_accounting = val != 0; > return 0;
On the other hand, inconsistent with mem_cgroup_hierarchy_write(), which applies the logic in the same way I did here.
> NFI about the logic... > On the face of it the tests don't seem related to each other > or to the assignment!
How so?
If parent's use_hierarchy is set, we can't set this value (we need to have a parent for that to even matter).
We also can't set it if we already have any children - otherwise all the on-the-fly adjustments become hell-on-earth.
As for = val != 0, sorry, but I completely disagree this is easier than !!val. Not to mention the !!val notation is already pretty widespread in the kernel.
> David > > > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email:<a href=ilto:"dont@kvack.org"> email@kvack.org</a>
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