On 21/02/2023 17:45, Pavel Begunkov wrote:
> On 2/21/23 13:57, Breno Leitao wrote:
>> Having cache entries linked using the hlist format brings no benefit, and
>> also requires an unnecessary extra pointer address per cache entry.
>>
>> Use the internal io_wq_work_node single-linked list for the internal
>> alloc caches (async_msghdr and async_poll)
>>
>> This is required to be able to use KASAN on cache entries, since we do
>> not need to touch unused (and poisoned) cache entries when adding more
>> entries to the list.
>
> Looks good, a few nits
>
>>
>> Suggested-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
>> Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
>> ---
>> include/linux/io_uring_types.h | 2 +-
>> io_uring/alloc_cache.h | 27 +++++++++++++++------------
>> 2 files changed, 16 insertions(+), 13 deletions(-)
>>
>> diff --git a/include/linux/io_uring_types.h
>> b/include/linux/io_uring_types.h
>> index 0efe4d784358..efa66b6c32c9 100644
>> --- a/include/linux/io_uring_types.h
>> +++ b/include/linux/io_uring_types.h
>> @@ -188,7 +188,7 @@ struct io_ev_fd {
>> };
>>
> [...]
>> - if (!hlist_empty(&cache->list)) {
>> - struct hlist_node *node = cache->list.first;
>> -
>> - hlist_del(node);
>> - return container_of(node, struct io_cache_entry, node);
>> + struct io_wq_work_node *node;
>> + struct io_cache_entry *entry;
>> +
>> + if (cache->list.next) {
>> + node = cache->list.next;
>> + entry = container_of(node, struct io_cache_entry, node);
>
> I'd prefer to get rid of the node var, it'd be a bit cleaner
> than keeping two pointers to the same chunk.
>
> entry = container_of(node, struct io_cache_entry,
> cache->list.next);
>
>> + cache->list.next = node->next;
>> + return entry;
>> }
>> return NULL;
>> @@ -35,19 +38,19 @@ static inline struct io_cache_entry
>> *io_alloc_cache_get(struct io_alloc_cache *c
>> static inline void io_alloc_cache_init(struct io_alloc_cache *cache)
>> {
>> - INIT_HLIST_HEAD(&cache->list);
>> + cache->list.next = NULL;
>> cache->nr_cached = 0;
>> }
>> static inline void io_alloc_cache_free(struct io_alloc_cache *cache,
>> void (*free)(struct io_cache_entry *))
>> {
>> - while (!hlist_empty(&cache->list)) {
>> - struct hlist_node *node = cache->list.first;
>> + struct io_cache_entry *entry;
>> - hlist_del(node);
>> - free(container_of(node, struct io_cache_entry, node));
>> + while ((entry = io_alloc_cache_get(cache))) {
>> + free(entry);
>
> We don't need brackets here.
The extra brackets are required if we are assignments in if, otherwise
the compiler raises a warning (bugprone-assignment-in-if-condition)
> Personally, I don't have anything
> against assignments in if, but it's probably better to avoid them
Sure. I will remove the assignents in "if" part and maybe replicate what
we have
in io_alloc_cache_get(). Something as:
if (cache->list.next) {
node = cache->list.next;
Thanks for the review!
