Re: [PATCH V2 1/4] RDMA/core: Add protection for shared CQs used by ULPs

[Yamin Friedman <yaminf@mellanox.com>]

On 5/18/2020 10:54 AM, Leon Romanovsky wrote:
> On Wed, May 13, 2020 at 02:52:40PM +0300, Yamin Friedman wrote:
>> A pre-step for adding shared CQs. Add the infrastructure to prevent
>> shared CQ users from altering the CQ configurations. For now all cqs are
>> marked as private (non-shared). The core driver should use the new force
>> functions to perform resize/destroy/moderation changes that are not
>> allowed for users of shared CQs.
>>
>> Signed-off-by: Yamin Friedman <yaminf@mellanox.com>
>> Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
>> Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
>> ---
>>   drivers/infiniband/core/cq.c    | 18 ++++++++++++------
>>   drivers/infiniband/core/verbs.c |  9 +++++++++
>>   include/rdma/ib_verbs.h         |  8 ++++++++
>>   3 files changed, 29 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c
>> index 4f25b24..04046eb 100644
>> --- a/drivers/infiniband/core/cq.c
>> +++ b/drivers/infiniband/core/cq.c
>> @@ -300,12 +300,7 @@ struct ib_cq *__ib_alloc_cq_any(struct ib_device *dev, void *private,
>>   }
>>   EXPORT_SYMBOL(__ib_alloc_cq_any);
>>
>> -/**
>> - * ib_free_cq_user - free a completion queue
>> - * @cq:		completion queue to free.
>> - * @udata:	User data or NULL for kernel object
>> - */
>> -void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata)
>> +static void _ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata)
>>   {
>>   	if (WARN_ON_ONCE(atomic_read(&cq->usecnt)))
>>   		return;
>> @@ -333,4 +328,15 @@ void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata)
>>   	kfree(cq->wc);
>>   	kfree(cq);
>>   }
>> +
>> +/**
>> + * ib_free_cq_user - free a completion queue
>> + * @cq:		completion queue to free.
>> + * @udata:	User data or NULL for kernel object
>> + */
>> +void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata)
>> +{
>> +	if (!cq->shared)
>> +		_ib_free_cq_user(cq, udata);
>> +}
>>   EXPORT_SYMBOL(ib_free_cq_user);
> All CQs from the pool will have "shared" boolean set and you don't need
> to create an extra wrapper, simply put this "if (cq->shared) return;"
> line in original ib_free_cq_user(). Just don't forget to set "shared"
> to be false in ib_cq_pool_destroy().
Makes sense.
>
>> diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
>> index bf0249f..d1bacd7 100644
>> --- a/drivers/infiniband/core/verbs.c
>> +++ b/drivers/infiniband/core/verbs.c
>> @@ -1990,6 +1990,9 @@ struct ib_cq *__ib_create_cq(struct ib_device *device,
>>
>>   int rdma_set_cq_moderation(struct ib_cq *cq, u16 cq_count, u16 cq_period)
>>   {
>> +	if (cq->shared)
>> +		return -EOPNOTSUPP;
>> +
>>   	return cq->device->ops.modify_cq ?
>>   		cq->device->ops.modify_cq(cq, cq_count,
>>   					  cq_period) : -EOPNOTSUPP;
>> @@ -1998,6 +2001,9 @@ int rdma_set_cq_moderation(struct ib_cq *cq, u16 cq_count, u16 cq_period)
>>
>>   int ib_destroy_cq_user(struct ib_cq *cq, struct ib_udata *udata)
>>   {
>> +	if (cq->shared)
>> +		return -EOPNOTSUPP;
>> +
>>   	if (atomic_read(&cq->usecnt))
>>   		return -EBUSY;
>>
>> @@ -2010,6 +2016,9 @@ int ib_destroy_cq_user(struct ib_cq *cq, struct ib_udata *udata)
>>
>>   int ib_resize_cq(struct ib_cq *cq, int cqe)
>>   {
>> +	if (cq->shared)
>> +		return -EOPNOTSUPP;
>> +
>>   	return cq->device->ops.resize_cq ?
>>   		cq->device->ops.resize_cq(cq, cqe, NULL) : -EOPNOTSUPP;
>>   }
>> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
>> index 4c488ca..b79737b 100644
>> --- a/include/rdma/ib_verbs.h
>> +++ b/include/rdma/ib_verbs.h
>> @@ -1582,6 +1582,7 @@ struct ib_cq {
>>   	 * Implementation details of the RDMA core, don't use in drivers:
>>   	 */
>>   	struct rdma_restrack_entry res;
>> +	bool shared;
> Lets do "u8 shared:1;" from the beginning.
Not sure what you mean "from the beginning".
>
>>   };
>>
>>   struct ib_srq {
>> @@ -3824,6 +3825,8 @@ static inline struct ib_cq *ib_alloc_cq_any(struct ib_device *dev,
>>    * ib_free_cq_user - Free kernel/user CQ
>>    * @cq: The CQ to free
>>    * @udata: Valid user data or NULL for kernel objects
>> + *
>> + * NOTE: this will fail for shared cqs
>>    */
>>   void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata);
>>
>> @@ -3832,6 +3835,7 @@ static inline struct ib_cq *ib_alloc_cq_any(struct ib_device *dev,
>>    * @cq: The CQ to free
>>    *
>>    * NOTE: for user cq use ib_free_cq_user with valid udata!
>> + * NOTE: this will fail for shared cqs
>>    */
>>   static inline void ib_free_cq(struct ib_cq *cq)
>>   {
>> @@ -3868,6 +3872,7 @@ struct ib_cq *__ib_create_cq(struct ib_device *device,
>>    * @cqe: The minimum size of the CQ.
>>    *
>>    * Users can examine the cq structure to determine the actual CQ size.
>> + * NOTE: Will fail for shared CQs.
>>    */
>>   int ib_resize_cq(struct ib_cq *cq, int cqe);
>>
>> @@ -3877,6 +3882,7 @@ struct ib_cq *__ib_create_cq(struct ib_device *device,
>>    * @cq_count: number of CQEs that will trigger an event
>>    * @cq_period: max period of time in usec before triggering an event
>>    *
>> + * NOTE: Will fail for shared CQs.
>>    */
>>   int rdma_set_cq_moderation(struct ib_cq *cq, u16 cq_count, u16 cq_period);
>>
>> @@ -3884,6 +3890,8 @@ struct ib_cq *__ib_create_cq(struct ib_device *device,
>>    * ib_destroy_cq_user - Destroys the specified CQ.
>>    * @cq: The CQ to destroy.
>>    * @udata: Valid user data or NULL for kernel objects
>> + *
>> + * NOTE: Will fail for shared CQs.
> Let's add WARN_ON_ONCE() to catch mistakes. No one should call to
> ib_destroy_cq_user() for the shared CQs.
Alright.
>
>>    */
>>   int ib_destroy_cq_user(struct ib_cq *cq, struct ib_udata *udata);
>>
>> --
>> 1.8.3.1
>>