[ Old patch is old. It implies this code is harmless. Anyway, I'm
testing some new stuff and trying to get feedback to see if it's
useful. - dan ]
Hello Sagi Grimberg,
The patch 14fb4171ab1c: "RDMA/cxgb3: Support the new memory
registration API" from Oct 13, 2015, leads to the following static
checker warning:
drivers/infiniband/hw/cxgb3/iwch_qp.c:173 build_memreg()
warn: dead code because of 'i == 10' and 'i < mhp->npages'
drivers/infiniband/hw/cxgb3/iwch_qp.c
149 static int build_memreg(union t3_wr *wqe, struct ib_reg_wr *wr,
150 u8 *flit_cnt, int *wr_cnt, struct t3_wq *wq)
151 {
152 struct iwch_mr *mhp = to_iwch_mr(wr->mr);
153 int i;
154 __be64 *p;
155
156 if (mhp->npages > T3_MAX_FASTREG_DEPTH)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
mhp->npages is 0-10.
157 return -EINVAL;
158 *wr_cnt = 1;
159 wqe->fastreg.stag = cpu_to_be32(wr->key);
160 wqe->fastreg.len = cpu_to_be32(mhp->ibmr.length);
161 wqe->fastreg.va_base_hi = cpu_to_be32(mhp->ibmr.iova >> 32);
162 wqe->fastreg.va_base_lo_fbo =
163 cpu_to_be32(mhp->ibmr.iova & 0xffffffff);
164 wqe->fastreg.page_type_perms = cpu_to_be32(
165 V_FR_PAGE_COUNT(mhp->npages) |
166 V_FR_PAGE_SIZE(ilog2(wr->mr->page_size) - 12) |
167 V_FR_TYPE(TPT_VATO) |
168 V_FR_PERMS(iwch_ib_to_tpt_access(wr->access)));
169 p = &wqe->fastreg.pbl_addrs[0];
170 for (i = 0; i < mhp->npages; i++, p++) {
^^^^^^^^^^^^^^^
That implied i is 0-9.
171
172 /* If we need a 2nd WR, then set it up */
173 if (i == T3_MAX_FASTREG_FRAG) {
^^^^^^^^^^^^^^^^^^^^^^^^
T3_MAX_FASTREG_FRAG is 10 so this condition can't be true.
174 *wr_cnt = 2;
175 wqe = (union t3_wr *)(wq->queue +
176 Q_PTR2IDX((wq->wptr+1), wq->size_log2));
177 build_fw_riwrh((void *)wqe, T3_WR_FASTREG, 0,
178 Q_GENBIT(wq->wptr + 1, wq->size_log2),
179 0, 1 + mhp->npages - T3_MAX_FASTREG_FRAG,
180 T3_EOP);
181
182 p = &wqe->pbl_frag.pbl_addrs[0];
183 }
184 *p = cpu_to_be64((u64)mhp->pages[i]);
185 }
186 *flit_cnt = 5 + mhp->npages;
187 if (*flit_cnt > 15)
188 *flit_cnt = 15;
189 return 0;
190 }
regards,
dan carpenter
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