Messages in this thread Patch in this message | | | Date | Wed, 19 Dec 2012 16:08:05 -0800 | From | Andrew Morton <> | Subject | Re: [patch 5/7] mm: vmscan: clean up get_scan_count() |
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On Mon, 17 Dec 2012 13:12:35 -0500 Johannes Weiner <hannes@cmpxchg.org> wrote:
> Reclaim pressure balance between anon and file pages is calculated > through a tuple of numerators and a shared denominator. > > Exceptional cases that want to force-scan anon or file pages configure > the numerators and denominator such that one list is preferred, which > is not necessarily the most obvious way: > > fraction[0] = 1; > fraction[1] = 0; > denominator = 1; > goto out; > > Make this easier by making the force-scan cases explicit and use the > fractionals only in case they are calculated from reclaim history. > > And bring the variable declarations/definitions in order. > > ... > > + u64 fraction[2], uninitialized_var(denominator);
Using uninitialized_var() puts Linus into rant mode. Unkindly, IMO: uninitialized_var() is documentarily useful and reduces bloat. There is a move afoot to replace it with
int foo = 0; /* gcc */
To avoid getting ranted at we can do
--- a/mm/vmscan.c~mm-vmscan-clean-up-get_scan_count-fix +++ a/mm/vmscan.c @@ -1658,7 +1658,8 @@ static void get_scan_count(struct lruvec unsigned long *nr) { struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; - u64 fraction[2], uninitialized_var(denominator); + u64 fraction[2]; + u64 denominator = 0; struct zone *zone = lruvec_zone(lruvec); unsigned long anon_prio, file_prio; enum scan_balance scan_balance; _ Which bloats the text by six bytes, but will force a nice div-by-zero if we ever hit that can't-happen path.
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