Messages in this thread | | | Date | Wed, 24 Nov 2021 21:29:11 -0800 | Subject | Re: [PATCH] mm: Use BUG_ON instead of if condition followed by BUG | From | John Hubbard <> |
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On 11/24/21 19:32, Matthew Wilcox wrote: > On Wed, Nov 24, 2021 at 02:45:59PM -0800, John Hubbard wrote: >> @@ -2201,13 +2201,12 @@ static int __ref try_remove_memory(u64 start, u64 size) >> */ >> void __remove_memory(u64 start, u64 size) >> { >> - >> + int ret = try_remove_memory(start, size); >> /* >> * trigger BUG() if some memory is not offlined prior to calling this >> * function >> */ >> - if (try_remove_memory(start, size)) >> - BUG(); >> + BUG_ON(ret); >> } > > I'd rather leave it the way it is. I don't see why the version you > propose is better.
In isolation, it's *not* better. It's only potentially useful in the context of "code plus tools". That is to say, if the coccinelle change request were rejected, then this provides a way forward that is not worse than the existing code, and also works around the warning.
> >> ...and by the way, while going to type that, I immediately stumbled upon >> another pre-existing case of this sort of thing, in try_remove_memory(), >> which does this: >> >> static int __ref try_remove_memory(u64 start, u64 size) >> { >> struct vmem_altmap mhp_altmap = {}; >> struct vmem_altmap *altmap = NULL; >> unsigned long nr_vmemmap_pages; >> int rc = 0, nid = NUMA_NO_NODE; >> >> BUG_ON(check_hotplug_memory_range(start, size)); > > That needs to be fixed.
Yes it does. :) I pointed it out in hopes that Chiminghao might be inspired to go find and fix some of these.
thanks, -- John Hubbard NVIDIA
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