> On 17 Jun 2021, at 09:38, Leon Romanovsky <leon@xxxxxxxxxx> wrote:
>
> On Thu, Jun 17, 2021 at 06:56:15AM +0000, Haakon Bugge wrote:
>>
>>
>>> 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?
>
> Yes, please
>
>>
>> Also, do you want it checkpatch clean? Then I need the /* set_bit() does not imply a memory barrier */ comments.
>
> It is always safer to send checkpatch clean patches. The most important
> part is to have W=1 clean patches, our subsystem is one warning away from
> being warnings-free one.
>
>>
>> Thanks for you review, Leon.
>
> Thank you for listening :)
>From checkpatch:
ERROR: inline keyword should sit between storage class and type
#47: FILE: drivers/infiniband/core/cma.c:51:
+inline static void set_bit_mb(unsigned long nr, unsigned long *flags)
>From W=1:
CC [M] /home/hbugge/git/linux-uek/drivers/infiniband/core/cma.o
/home/hbugge/git/linux-uek/drivers/infiniband/core/cma.c:51:1: warning: ‘inline’ is not at beginning of declaration [-Wold-style-declaration]
static void inline set_bit_mb(unsigned long nr, unsigned long *flags)
^~~~~~
which one do you prefer?
Håkon
>>
>>
>> Håkon
>>
>>>
>>>> +
>>>> #endif /* _CMA_PRIV_H */
>>>> --
>>>> 1.8.3.1
