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48 #include <rdma/rdma_vt.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;
107 struct rvt_rwq *wq = qp->r_rq.wq;
111 /* sanity check pointers before trusting them */
113 if (head >= qp->r_rq.size)
116 if (tail >= qp->r_rq.size)
119 * Compute the number of credits available (RWQEs).
120 * There is a small chance that the pair of reads are
121 * not atomic, which is OK, since the fuzziness is
122 * resolved as further ACKs go out.
124 credits = head - tail;
125 if ((int)credits < 0)
126 credits += qp->r_rq.size;
128 * Binary search the credit table to find the code to
135 if (credit_table[x] == credits)
137 if (credit_table[x] > credits) {
145 aeth |= x << IB_AETH_CREDIT_SHIFT;
147 return cpu_to_be32(aeth);
149 EXPORT_SYMBOL(rvt_compute_aeth);
152 * rvt_get_credit - flush the send work queue of a QP
153 * @qp: the qp who's send work queue to flush
154 * @aeth: the Acknowledge Extended Transport Header
156 * The QP s_lock should be held.
158 void rvt_get_credit(struct rvt_qp *qp, u32 aeth)
160 struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
161 u32 credit = (aeth >> IB_AETH_CREDIT_SHIFT) & IB_AETH_CREDIT_MASK;
163 lockdep_assert_held(&qp->s_lock);
165 * If the credit is invalid, we can send
166 * as many packets as we like. Otherwise, we have to
167 * honor the credit field.
169 if (credit == IB_AETH_CREDIT_INVAL) {
170 if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
171 qp->s_flags |= RVT_S_UNLIMITED_CREDIT;
172 if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
173 qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
174 rdi->driver_f.schedule_send(qp);
177 } else if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
178 /* Compute new LSN (i.e., MSN + credit) */
179 credit = (aeth + credit_table[credit]) & IB_MSN_MASK;
180 if (rvt_cmp_msn(credit, qp->s_lsn) > 0) {
182 if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
183 qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
184 rdi->driver_f.schedule_send(qp);
189 EXPORT_SYMBOL(rvt_get_credit);