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SubjectRe: [PATCH] async: Let kfree() out of the critical area of the lock
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On 2019/9/25 23:20, Alexander Duyck wrote:
> On Wed, 2019-09-25 at 20:52 +0800, Yunfeng Ye wrote:
>> It's not necessary to put kfree() in the critical area of the lock, so
>> let it out.
>>
>> Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
>> ---
>> kernel/async.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/kernel/async.c b/kernel/async.c
>> index 4f9c1d6..1de270d 100644
>> --- a/kernel/async.c
>> +++ b/kernel/async.c
>> @@ -135,12 +135,12 @@ static void async_run_entry_fn(struct work_struct *work)
>> list_del_init(&entry->domain_list);
>> list_del_init(&entry->global_list);
>>
>> - /* 3) free the entry */
>> - kfree(entry);
>> atomic_dec(&entry_count);
>> -
>> spin_unlock_irqrestore(&async_lock, flags);
>>
>> + /* 3) free the entry */
>> + kfree(entry);
>> +
>> /* 4) wake up any waiters */
>> wake_up(&async_done);
>> }
>
> It probably wouldn't hurt to update the patch description to mention that
> async_schedule_node_domain does the allocation outside of the lock, then
> takes the lock and does the list addition and entry_count increment inside
> the critical section so this is just updating the code to match that it
> seems.
>
> Otherwise the change itself looks safe to me, though I am not sure there
> is a performance gain to be had so this is mostly just a cosmetic patch.
>
The async_lock is big global lock, I think it's good to put kfree() outside
to keep the critical area as short as possible.

thanks.

> Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
>
>
> .
>

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