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SubjectRe: [PATCH] mm/swap_slots.c: Remove unnecessary NULL pointer check
On Sat, Jan 09, 2021 at 03:09:43AM -0500, Miaohe Lin wrote:
> The cache->slots and cache->slots_ret is already checked before we try to
> drain it. And kvfree can handle the NULL pointer itself. So remove the
> NULL pointer check here.

> @@ -178,7 +178,7 @@ static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,
> swapcache_free_entries(cache->slots + cache->cur, cache->nr);
> cache->cur = 0;
> cache->nr = 0;
> - if (free_slots && cache->slots) {
> + if (free_slots) {

Prove that swapcache_free_entries() doesn't change cache->slots.

> @@ -188,13 +188,12 @@ static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,
> spin_lock_irq(&cache->free_lock);
> swapcache_free_entries(cache->slots_ret, cache->n_ret);
> cache->n_ret = 0;
> - if (free_slots && cache->slots_ret) {
> + if (free_slots) {

... or ->slots_ret

> - if (slots)
> - kvfree(slots);
> + kvfree(slots);

This is fine.

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