On Thu, Jun 17, 2021 at 09:19:26AM +0000, Haakon Bugge wrote:
>
>
> > 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?
The one that is written in CodingStyle - do not use inline functions in .c file.
BTW, it is "static inline void set_bit_mb" and not as you wrote.
Thanks
>
>
> Håkon
>
>
> >>
> >>
> >> Håkon
> >>
> >>>
> >>>> +
> >>>> #endif /* _CMA_PRIV_H */
> >>>> --
> >>>> 1.8.3.1
>
