lkml.org 
[lkml]   [2023]   [Feb]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 1/2] io_uring: Move from hlist to io_wq_work_node
From
On 2/21/23 18:38, Breno Leitao wrote:
> 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@gmail.com>
>>> Signed-off-by: Breno Leitao <leitao@debian.org>
>>> ---
>>>   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)

I mean braces / curly brackets.
>> 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!

--
Pavel Begunkov

\
 
 \ /
  Last update: 2023-03-27 00:30    [W:0.056 / U:2.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site