svcrdma: Scrub BUG_ON() and WARN_ON() call sites

Current convention is to avoid using BUG_ON() in places where an
oops could cause complete system failure.

Replace BUG_ON() call sites in svcrdma with an assertion error
message and allow execution to continue safely.

Some BUG_ON() calls are removed because they have never fired in
production (that we are aware of).

Some WARN_ON() calls are also replaced where a back trace is not
helpful; e.g., in a workqueue task.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

3 files changed, 49 insertions, 33 deletions

diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index b3b7bb85844d..577f8659ca30 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -95,14 +95,6 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
         rqstp->rq_respages = &rqstp->rq_pages[sge_no];
         rqstp->rq_next_page = rqstp->rq_respages + 1;
 
-        /* We should never run out of SGE because the limit is defined to
-         * support the max allowed RPC data length
-         */
-        BUG_ON(bc && (sge_no == ctxt->count));
-        BUG_ON((rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len)
-               != byte_count);
-        BUG_ON(rqstp->rq_arg.len != byte_count);
-
         /* If not all pages were used from the SGL, free the remaining ones */
         bc = sge_no;
         while (sge_no < ctxt->count) {
@@ -477,8 +469,6 @@ static int rdma_read_complete(struct svc_rqst *rqstp,
         int page_no;
         int ret;
 
-        BUG_ON(!head);
-
         /* Copy RPC pages */
         for (page_no = 0; page_no < head->count; page_no++) {
                 put_page(rqstp->rq_pages[page_no]);
@@ -567,7 +557,6 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
         }
         dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p, status=%d\n",
                 ctxt, rdma_xprt, rqstp, ctxt->wc_status);
-        BUG_ON(ctxt->wc_status != IB_WC_SUCCESS);
         atomic_inc(&rdma_stat_recv);
 
         /* Build up the XDR from the receive buffers. */
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index 9f1b50689c0f..7d79897959a4 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -60,8 +60,11 @@ static int map_xdr(struct svcxprt_rdma *xprt,
         u32 page_off;
         int page_no;
 
-        BUG_ON(xdr->len !=
-               (xdr->head[0].iov_len + xdr->page_len + xdr->tail[0].iov_len));
+        if (xdr->len !=
+            (xdr->head[0].iov_len + xdr->page_len + xdr->tail[0].iov_len)) {
+                pr_err("svcrdma: map_xdr: XDR buffer length error\n");
+                return -EIO;
+        }
 
         /* Skip the first sge, this is for the RPCRDMA header */
         sge_no = 1;
@@ -150,7 +153,11 @@ static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,
         int bc;
         struct svc_rdma_op_ctxt *ctxt;
 
-        BUG_ON(vec->count > RPCSVC_MAXPAGES);
+        if (vec->count > RPCSVC_MAXPAGES) {
+                pr_err("svcrdma: Too many pages (%lu)\n", vec->count);
+                return -EIO;
+        }
+
         dprintk("svcrdma: RDMA_WRITE rmr=%x, to=%llx, xdr_off=%d, "
                 "write_len=%d, vec->sge=%p, vec->count=%lu\n",
                 rmr, (unsigned long long)to, xdr_off,
@@ -190,7 +197,10 @@ static int send_write(struct svcxprt_rdma *xprt, struct svc_rqst *rqstp,
                 sge_off = 0;
                 sge_no++;
                 xdr_sge_no++;
-                BUG_ON(xdr_sge_no > vec->count);
+                if (xdr_sge_no > vec->count) {
+                        pr_err("svcrdma: Too many sges (%d)\n", xdr_sge_no);
+                        goto err;
+                }
                 bc -= sge_bytes;
                 if (sge_no == xprt->sc_max_sge)
                         break;
@@ -421,7 +431,10 @@ static int send_reply(struct svcxprt_rdma *rdma,
                 ctxt->sge[sge_no].lkey = rdma->sc_dma_lkey;
                 ctxt->sge[sge_no].length = sge_bytes;
         }
-        BUG_ON(byte_count != 0);
+        if (byte_count != 0) {
+                pr_err("svcrdma: Could not map %d bytes\n", byte_count);
+                goto err;
+        }
 
         /* Save all respages in the ctxt and remove them from the
          * respages array. They are our pages until the I/O
@@ -442,7 +455,10 @@ static int send_reply(struct svcxprt_rdma *rdma,
         }
         rqstp->rq_next_page = rqstp->rq_respages + 1;
 
-        BUG_ON(sge_no > rdma->sc_max_sge);
+        if (sge_no > rdma->sc_max_sge) {
+                pr_err("svcrdma: Too many sges (%d)\n", sge_no);
+                goto err;
+        }
         memset(&send_wr, 0, sizeof send_wr);
         ctxt->wr_op = IB_WR_SEND;
         send_wr.wr_id = (unsigned long)ctxt;
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 4ba11d0cefe1..f2e059bbab42 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -139,7 +139,6 @@ void svc_rdma_put_context(struct svc_rdma_op_ctxt *ctxt, int free_pages)
         struct svcxprt_rdma *xprt;
         int i;
 
-        BUG_ON(!ctxt);
         xprt = ctxt->xprt;
         if (free_pages)
                 for (i = 0; i < ctxt->count; i++)
@@ -339,12 +338,14 @@ static void process_context(struct svcxprt_rdma *xprt,
 
         switch (ctxt->wr_op) {
         case IB_WR_SEND:
-                BUG_ON(ctxt->frmr);
+                if (ctxt->frmr)
+                        pr_err("svcrdma: SEND: ctxt->frmr != NULL\n");
                 svc_rdma_put_context(ctxt, 1);
                 break;
 
         case IB_WR_RDMA_WRITE:
-                BUG_ON(ctxt->frmr);
+                if (ctxt->frmr)
+                        pr_err("svcrdma: WRITE: ctxt->frmr != NULL\n");
                 svc_rdma_put_context(ctxt, 0);
                 break;
 
@@ -353,19 +354,21 @@ static void process_context(struct svcxprt_rdma *xprt,
                 svc_rdma_put_frmr(xprt, ctxt->frmr);
                 if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
                         struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr;
-                        BUG_ON(!read_hdr);
-                        spin_lock_bh(&xprt->sc_rq_dto_lock);
-                        set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
-                        list_add_tail(&read_hdr->dto_q,
-                                      &xprt->sc_read_complete_q);
-                        spin_unlock_bh(&xprt->sc_rq_dto_lock);
+                        if (read_hdr) {
+                                spin_lock_bh(&xprt->sc_rq_dto_lock);
+                                set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
+                                list_add_tail(&read_hdr->dto_q,
+                                              &xprt->sc_read_complete_q);
+                                spin_unlock_bh(&xprt->sc_rq_dto_lock);
+                        } else {
+                                pr_err("svcrdma: ctxt->read_hdr == NULL\n");
+                        }
                         svc_xprt_enqueue(&xprt->sc_xprt);
                 }
                 svc_rdma_put_context(ctxt, 0);
                 break;
 
         default:
-                BUG_ON(1);
                 printk(KERN_ERR "svcrdma: unexpected completion type, "
                        "opcode=%d\n",
                        ctxt->wr_op);
@@ -513,7 +516,10 @@ int svc_rdma_post_recv(struct svcxprt_rdma *xprt)
         buflen = 0;
         ctxt->direction = DMA_FROM_DEVICE;
         for (sge_no = 0; buflen < xprt->sc_max_req_size; sge_no++) {
-                BUG_ON(sge_no >= xprt->sc_max_sge);
+                if (sge_no >= xprt->sc_max_sge) {
+                        pr_err("svcrdma: Too many sges (%d)\n", sge_no);
+                        goto err_put_ctxt;
+                }
                 page = svc_rdma_get_page();
                 ctxt->pages[sge_no] = page;
                 pa = ib_dma_map_page(xprt->sc_cm_id->device,
@@ -820,7 +826,7 @@ void svc_rdma_put_frmr(struct svcxprt_rdma *rdma,
         if (frmr) {
                 frmr_unmap_dma(rdma, frmr);
                 spin_lock_bh(&rdma->sc_frmr_q_lock);
-                BUG_ON(!list_empty(&frmr->frmr_list));
+                WARN_ON_ONCE(!list_empty(&frmr->frmr_list));
                 list_add(&frmr->frmr_list, &rdma->sc_frmr_q);
                 spin_unlock_bh(&rdma->sc_frmr_q_lock);
         }
@@ -1123,7 +1129,9 @@ static void __svc_rdma_free(struct work_struct *work)
         dprintk("svcrdma: svc_rdma_free(%p)\n", rdma);
 
         /* We should only be called from kref_put */
-        BUG_ON(atomic_read(&rdma->sc_xprt.xpt_ref.refcount) != 0);
+        if (atomic_read(&rdma->sc_xprt.xpt_ref.refcount) != 0)
+                pr_err("svcrdma: sc_xprt still in use? (%d)\n",
+                       atomic_read(&rdma->sc_xprt.xpt_ref.refcount));
 
         /*
          * Destroy queued, but not processed read completions. Note
@@ -1151,8 +1159,12 @@ static void __svc_rdma_free(struct work_struct *work)
         }
 
         /* Warn if we leaked a resource or under-referenced */
-        WARN_ON(atomic_read(&rdma->sc_ctxt_used) != 0);
-        WARN_ON(atomic_read(&rdma->sc_dma_used) != 0);
+        if (atomic_read(&rdma->sc_ctxt_used) != 0)
+                pr_err("svcrdma: ctxt still in use? (%d)\n",
+                       atomic_read(&rdma->sc_ctxt_used));
+        if (atomic_read(&rdma->sc_dma_used) != 0)
+                pr_err("svcrdma: dma still in use? (%d)\n",
+                       atomic_read(&rdma->sc_dma_used));
 
         /* De-allocate fastreg mr */
         rdma_dealloc_frmr_q(rdma);
@@ -1252,7 +1264,6 @@ int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
         if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
                 return -ENOTCONN;
 
-        BUG_ON(wr->send_flags != IB_SEND_SIGNALED);
         wr_count = 1;
         for (n_wr = wr->next; n_wr; n_wr = n_wr->next)
                 wr_count++;