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48 #include <rdma/rdmavt_qp.h>
49 #include <rdma/ib_hdrs.h>
52 * Convert the AETH credit code into the number of credits.
54 static const u16 credit_table[31] = {
89 * rvt_compute_aeth - compute the AETH (syndrome + MSN)
90 * @qp: the queue pair to compute the AETH for
94 __be32 rvt_compute_aeth(struct rvt_qp *qp)
96 u32 aeth = qp->r_msn & IB_MSN_MASK;
100 * Shared receive queues don't generate credits.
101 * Set the credit field to the invalid value.
103 aeth |= IB_AETH_CREDIT_INVAL << IB_AETH_CREDIT_SHIFT;
110 credits = READ_ONCE(qp->r_rq.kwq->count);
112 /* sanity check pointers before trusting them */
114 head = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->head);
115 tail = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->tail);
117 head = READ_ONCE(qp->r_rq.kwq->head);
118 tail = READ_ONCE(qp->r_rq.kwq->tail);
120 if (head >= qp->r_rq.size)
122 if (tail >= qp->r_rq.size)
125 * Compute the number of credits available (RWQEs).
126 * There is a small chance that the pair of reads are
127 * not atomic, which is OK, since the fuzziness is
128 * resolved as further ACKs go out.
130 credits = rvt_get_rq_count(&qp->r_rq, head, tail);
133 * Binary search the credit table to find the code to
140 if (credit_table[x] == credits)
142 if (credit_table[x] > credits) {
150 aeth |= x << IB_AETH_CREDIT_SHIFT;
152 return cpu_to_be32(aeth);
154 EXPORT_SYMBOL(rvt_compute_aeth);
157 * rvt_get_credit - flush the send work queue of a QP
158 * @qp: the qp who's send work queue to flush
159 * @aeth: the Acknowledge Extended Transport Header
161 * The QP s_lock should be held.
163 void rvt_get_credit(struct rvt_qp *qp, u32 aeth)
165 struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
166 u32 credit = (aeth >> IB_AETH_CREDIT_SHIFT) & IB_AETH_CREDIT_MASK;
168 lockdep_assert_held(&qp->s_lock);
170 * If the credit is invalid, we can send
171 * as many packets as we like. Otherwise, we have to
172 * honor the credit field.
174 if (credit == IB_AETH_CREDIT_INVAL) {
175 if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
176 qp->s_flags |= RVT_S_UNLIMITED_CREDIT;
177 if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
178 qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
179 rdi->driver_f.schedule_send(qp);
182 } else if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
183 /* Compute new LSN (i.e., MSN + credit) */
184 credit = (aeth + credit_table[credit]) & IB_MSN_MASK;
185 if (rvt_cmp_msn(credit, qp->s_lsn) > 0) {
187 if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
188 qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
189 rdi->driver_f.schedule_send(qp);
194 EXPORT_SYMBOL(rvt_get_credit);
197 * rvt_restart_sge - rewind the sge state for a wqe
198 * @ss: the sge state pointer
199 * @wqe: the wqe to rewind
200 * @len: the data length from the start of the wqe in bytes
202 * Returns the remaining data length.
204 u32 rvt_restart_sge(struct rvt_sge_state *ss, struct rvt_swqe *wqe, u32 len)
206 ss->sge = wqe->sg_list[0];
207 ss->sg_list = wqe->sg_list + 1;
208 ss->num_sge = wqe->wr.num_sge;
209 ss->total_len = wqe->length;
210 rvt_skip_sge(ss, len, false);
211 return wqe->length - len;
213 EXPORT_SYMBOL(rvt_restart_sge);