> On 17 Jun 2021, at 08:51, Leon Romanovsky <leon@xxxxxxxxxx> wrote:
>
> On Wed, Jun 16, 2021 at 04:35:53PM +0200, Håkon Bugge wrote:
>> The struct rdma_id_private contains three bit-fields, tos_set,
>> timeout_set, and min_rnr_timer_set. These are set by accessor
>> functions without any synchronization. If two or all accessor
>> functions are invoked in close proximity in time, there will be
>> Read-Modify-Write from several contexts to the same variable, and the
>> result will be intermittent.
>>
>> Replace with a flag variable and inline functions for set and get.
>>
>> Signed-off-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
>> Signed-off-by: Hans Westgaard Ry<hans.westgaard.ry@xxxxxxxxxx>
>> ---
>> drivers/infiniband/core/cma.c | 24 +++++++++++-------------
>> drivers/infiniband/core/cma_priv.h | 28 +++++++++++++++++++++++++---
>> 2 files changed, 36 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
>> index 2b9ffc2..fe609e7 100644
>> --- a/drivers/infiniband/core/cma.c
>> +++ b/drivers/infiniband/core/cma.c
>> @@ -844,9 +844,7 @@ static void cma_id_put(struct rdma_id_private *id_priv)
>> id_priv->id.event_handler = event_handler;
>> id_priv->id.ps = ps;
>> id_priv->id.qp_type = qp_type;
>> - id_priv->tos_set = false;
>> - id_priv->timeout_set = false;
>> - id_priv->min_rnr_timer_set = false;
>> + id_priv->flags = 0;
>
> It is not needed, id_priv is allocated with kzalloc.
I agree. Did put it in due the foo = false.
>
>> id_priv->gid_type = IB_GID_TYPE_IB;
>> spin_lock_init(&id_priv->lock);
>> mutex_init(&id_priv->qp_mutex);
>> @@ -1134,10 +1132,10 @@ int rdma_init_qp_attr(struct rdma_cm_id *id, struct ib_qp_attr *qp_attr,
>> ret = -ENOSYS;
>> }
>>
>> - if ((*qp_attr_mask & IB_QP_TIMEOUT) && id_priv->timeout_set)
>> + if ((*qp_attr_mask & IB_QP_TIMEOUT) && get_TIMEOUT_SET(id_priv->flags))
>> qp_attr->timeout = id_priv->timeout;
>>
>> - if ((*qp_attr_mask & IB_QP_MIN_RNR_TIMER) && id_priv->min_rnr_timer_set)
>> + if ((*qp_attr_mask & IB_QP_MIN_RNR_TIMER) && get_MIN_RNR_TIMER_SET(id_priv->flags))
>> qp_attr->min_rnr_timer = id_priv->min_rnr_timer;
>>
>> return ret;
>> @@ -2472,7 +2470,7 @@ static int cma_iw_listen(struct rdma_id_private *id_priv, int backlog)
>> return PTR_ERR(id);
>>
>> id->tos = id_priv->tos;
>> - id->tos_set = id_priv->tos_set;
>> + id->tos_set = get_TOS_SET(id_priv->flags);
>> id->afonly = id_priv->afonly;
>> id_priv->cm_id.iw = id;
>>
>> @@ -2533,7 +2531,7 @@ static int cma_listen_on_dev(struct rdma_id_private *id_priv,
>> cma_id_get(id_priv);
>> dev_id_priv->internal_id = 1;
>> dev_id_priv->afonly = id_priv->afonly;
>> - dev_id_priv->tos_set = id_priv->tos_set;
>> + dev_id_priv->flags = id_priv->flags;
>> dev_id_priv->tos = id_priv->tos;
>>
>> ret = rdma_listen(&dev_id_priv->id, id_priv->backlog);
>> @@ -2582,7 +2580,7 @@ void rdma_set_service_type(struct rdma_cm_id *id, int tos)
>>
>> id_priv = container_of(id, struct rdma_id_private, id);
>> id_priv->tos = (u8) tos;
>> - id_priv->tos_set = true;
>> + set_TOS_SET(id_priv->flags);
>> }
>> EXPORT_SYMBOL(rdma_set_service_type);
>>
>> @@ -2610,7 +2608,7 @@ int rdma_set_ack_timeout(struct rdma_cm_id *id, u8 timeout)
>>
>> id_priv = container_of(id, struct rdma_id_private, id);
>> id_priv->timeout = timeout;
>> - id_priv->timeout_set = true;
>> + set_TIMEOUT_SET(id_priv->flags);
>>
>> return 0;
>> }
>> @@ -2647,7 +2645,7 @@ int rdma_set_min_rnr_timer(struct rdma_cm_id *id, u8 min_rnr_timer)
>>
>> id_priv = container_of(id, struct rdma_id_private, id);
>> id_priv->min_rnr_timer = min_rnr_timer;
>> - id_priv->min_rnr_timer_set = true;
>> + set_MIN_RNR_TIMER_SET(id_priv->flags);
>>
>> return 0;
>> }
>> @@ -3033,7 +3031,7 @@ static int cma_resolve_iboe_route(struct rdma_id_private *id_priv)
>>
>> u8 default_roce_tos = id_priv->cma_dev->default_roce_tos[id_priv->id.port_num -
>> rdma_start_port(id_priv->cma_dev->device)];
>> - u8 tos = id_priv->tos_set ? id_priv->tos : default_roce_tos;
>> + u8 tos = get_TOS_SET(id_priv->flags) ? id_priv->tos : default_roce_tos;
>>
>>
>> work = kzalloc(sizeof *work, GFP_KERNEL);
>> @@ -3081,7 +3079,7 @@ static int cma_resolve_iboe_route(struct rdma_id_private *id_priv)
>> * PacketLifeTime = local ACK timeout/2
>> * as a reasonable approximation for RoCE networks.
>> */
>> - route->path_rec->packet_life_time = id_priv->timeout_set ?
>> + route->path_rec->packet_life_time = get_TIMEOUT_SET(id_priv->flags) ?
>> id_priv->timeout - 1 : CMA_IBOE_PACKET_LIFETIME;
>>
>> if (!route->path_rec->mtu) {
>> @@ -4107,7 +4105,7 @@ static int cma_connect_iw(struct rdma_id_private *id_priv,
>> return PTR_ERR(cm_id);
>>
>> cm_id->tos = id_priv->tos;
>> - cm_id->tos_set = id_priv->tos_set;
>> + cm_id->tos_set = get_TOS_SET(id_priv->flags);
>> id_priv->cm_id.iw = cm_id;
>>
>> memcpy(&cm_id->local_addr, cma_src_addr(id_priv),
>> diff --git a/drivers/infiniband/core/cma_priv.h b/drivers/infiniband/core/cma_priv.h
>> index 5c463da..2c1694f 100644
>> --- a/drivers/infiniband/core/cma_priv.h
>> +++ b/drivers/infiniband/core/cma_priv.h
>> @@ -82,11 +82,9 @@ struct rdma_id_private {
>> u32 qkey;
>> u32 qp_num;
>> u32 options;
>> + unsigned long flags;
>> u8 srq;
>> u8 tos;
>> - u8 tos_set:1;
>> - u8 timeout_set:1;
>> - u8 min_rnr_timer_set:1;
>> u8 reuseaddr;
>> u8 afonly;
>> u8 timeout;
>> @@ -127,4 +125,28 @@ int cma_set_default_roce_tos(struct cma_device *dev, u32 port,
>> u8 default_roce_tos);
>> struct ib_device *cma_get_ib_dev(struct cma_device *dev);
>>
>> +#define BIT_ACCESS_FUNCTIONS(b) \
>> + static inline void set_##b(unsigned long flags) \
>> + { \
>> + /* set_bit() does not imply a memory barrier */ \
>> + smp_mb__before_atomic(); \
>> + set_bit(b, &flags); \
>> + /* set_bit() does not imply a memory barrier */ \
>> + smp_mb__after_atomic(); \
>> + } \
>> + static inline bool get_##b(unsigned long flags) \
>> + { \
>> + return test_bit(b, &flags); \
>> + }
>> +
>> +enum cm_id_flag_bits {
This should be called cm_id_priv_flags_bits.
>> + TOS_SET,
>> + TIMEOUT_SET,
>> + MIN_RNR_TIMER_SET,
>> +};
>> +
>> +BIT_ACCESS_FUNCTIONS(TIMEOUT_SET);
>> +BIT_ACCESS_FUNCTIONS(TOS_SET);
>> +BIT_ACCESS_FUNCTIONS(MIN_RNR_TIMER_SET);
>
> I would prefer one function that has same syntax as set_bit() instead of
> introducing two new that built with macros.
>
> Something like this:
> static inline set_bit_mb(long nr, unsigned long *flags)
> {
> smp_mb__before_atomic();
> set_bit(nr, flags);
> smp_mb__after_atomic();
> }
OK. I should also probably move this to cma.c, since it is not used outside cma.c?
Also, do you want it checkpatch clean? Then I need the /* set_bit() does not imply a memory barrier */ comments.
Thanks for you review, Leon.
Håkon
>
>> +
>> #endif /* _CMA_PRIV_H */
>> --
>> 1.8.3.1
