[PATCH v2 04/10] svcrdma: Scrub BUG_ON() and WARN_ON() call sites

Chuck Lever
2015-01-13T16:03:03Z

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-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 11 --------
net/sunrpc/xprtrdma/svc_rdma_sendto.c | 28 +++++++++++++++-----
net/sunrpc/xprtrdma/svc_rdma_transport.c | 43 +++++++++++++++++++-----------
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 b3b7bb8..577f865 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 9f1b506..7d79897 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 4ba11d0..f2e059b 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++;