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SubjectRe: [PATCH] RDMA/irdma: Improve the way 'cqp_request' structures are cleaned when they are recycled
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Le 20/07/2021 à 14:23, Leon Romanovsky a écrit :
> On Mon, Jul 19, 2021 at 07:02:15PM +0200, Christophe JAILLET wrote:
>> A set of IRDMA_CQP_SW_SQSIZE_2048 (i.e. 2048) 'cqp_request' are
>> pre-allocated and zeroed in 'irdma_create_cqp()' (hw.c). These
>> structures are managed with the 'cqp->cqp_avail_reqs' list which keeps
>> track of available entries.
>>
>> In 'irdma_free_cqp_request()' (utils.c), when an entry is recycled and goes
>> back to the 'cqp_avail_reqs' list, some fields are reseted.
>>
>> However, one of these fields, 'compl_info', is initialized within
>> 'irdma_alloc_and_get_cqp_request()'.
>>
>> Move the corresponding memset to 'irdma_free_cqp_request()' so that the
>> clean-up is done in only one place. This makes the logic more easy to
>> understand.
>
> I'm not so sure. The function irdma_alloc_and_get_cqp_request() returns
> prepared cqp_request and all users expect that it will returned cleaned
> one. The reliance on some other place to clear part of the structure is
> prone to errors.

Ok, so maybe, moving:
cqp_request->request_done = false;
cqp_request->callback_fcn = NULL;
cqp_request->waiting = false;
from 'irdma_free_cqp_request()' to 'irdma_alloc_and_get_cqp_request()'
to make explicit what is reseted makes more sense?

From my point of view, it is same same: all (re)initialization are done
at 1 place only.

This would also avoid setting 'waiting' twice (once to false in
'irdma_free_cqp_request()' and one to 'wait'
'irdma_alloc_and_get_cqp_request()')


CJ
>
> Thanks
>
>>
>> This also saves this memset in the case that the 'cqp_avail_reqs' list is
>> empty and a new 'cqp_request' structure must be allocated. This memset is
>> useless, because the structure is already kzalloc'ed.
>>
>> Signed-off-by: Christophe JAILLET <christophe.jaillet-39ZsbGIQGT5GWvitb5QawA@public.gmane.org>
>> ---
>> drivers/infiniband/hw/irdma/utils.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/infiniband/hw/irdma/utils.c b/drivers/infiniband/hw/irdma/utils.c
>> index 5bbe44e54f9a..66711024d38b 100644
>> --- a/drivers/infiniband/hw/irdma/utils.c
>> +++ b/drivers/infiniband/hw/irdma/utils.c
>> @@ -445,7 +445,6 @@ struct irdma_cqp_request *irdma_alloc_and_get_cqp_request(struct irdma_cqp *cqp,
>>
>> cqp_request->waiting = wait;
>> refcount_set(&cqp_request->refcnt, 1);
>> - memset(&cqp_request->compl_info, 0, sizeof(cqp_request->compl_info));
>>
>> return cqp_request;
>> }
>> @@ -475,6 +474,7 @@ void irdma_free_cqp_request(struct irdma_cqp *cqp,
>> cqp_request->request_done = false;
>> cqp_request->callback_fcn = NULL;
>> cqp_request->waiting = false;
>> + memset(&cqp_request->compl_info, 0, sizeof(cqp_request->compl_info));
>>
>> spin_lock_irqsave(&cqp->req_lock, flags);
>> list_add_tail(&cqp_request->list, &cqp->cqp_avail_reqs);
>> --
>> 2.30.2
>>
>

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