On 3/22/2018 12:30 PM, Sinan Kaya wrote: > Code includes wmb() followed by writel() in multiple places. writel() > already has a barrier on some architectures like arm64. > > This ends up CPU observing two barriers back to back before executing the > register write. > > Since code already has an explicit barrier call, changing writel() to > writel_relaxed(). > > Signed-off-by: Sinan Kaya <okaya@xxxxxxxxxxxxxx> > --- > drivers/infiniband/hw/qedr/verbs.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/infiniband/hw/qedr/verbs.c b/drivers/infiniband/hw/qedr/verbs.c > index 53f00db..d1cf9a0 100644 > --- a/drivers/infiniband/hw/qedr/verbs.c > +++ b/drivers/infiniband/hw/qedr/verbs.c > @@ -35,6 +35,7 @@ > #include <net/ipv6.h> > #include <net/udp.h> > #include <linux/iommu.h> > +#include <linux/io-64-nonatomic-hi-lo.h> what should we do here? change include? drop writeq_relaxed? > > #include <rdma/ib_verbs.h> > #include <rdma/ib_user_verbs.h> > @@ -860,7 +861,7 @@ static void doorbell_cq(struct qedr_cq *cq, u32 cons, u8 flags) > wmb(); > cq->db.data.agg_flags = flags; > cq->db.data.value = cpu_to_le32(cons); > - writeq(cq->db.raw, cq->db_addr); > + writeq_relaxed(cq->db.raw, cq->db_addr); > > /* Make sure write would stick */ > mmiowb(); > @@ -3338,7 +3339,7 @@ int qedr_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr, > > qp->rq.db_data.data.value++; > > - writel(qp->rq.db_data.raw, qp->rq.db); > + writel_relaxed(qp->rq.db_data.raw, qp->rq.db); > > /* Make sure write sticks */ > mmiowb(); > -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
