[PATCH v4 01/21] xprtrdma: Fix panic in rpcrdma_register_frmr_external()

Chuck Lever
2014-07-22T14:51:07Z

seg1->mr_nsegs is not yet initialized when it is used to unmap
segments during an error exit. Use the same unmapping logic for
all error exits.

"if (frmr_wr.wr.fast_reg.length < len) {" used to be a BUG_ON check.
The broken code will never be executed under normal operation.

Fixes: c977dea (xprtrdma: Remove BUG_ON() call sites)
Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
Tested-by: Shirley Ma <shirley.ma-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Devesh Sharma <devesh.sharma-laKkSmNT4hbQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/verbs.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 13dbd1c..78bd7c6 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1545,9 +1545,8 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
frmr_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
frmr_wr.wr.fast_reg.length = page_no << PAGE_SHIFT;
if (frmr_wr.wr.fast_reg.length < len) {
- while (seg1->mr_nsegs--)
- rpcrdma_unmap_one(ia, seg++);
- return -EIO;
+ rc = -EIO;
+ goto out_err;
}

/* Bump the key */
@@ -1565,8 +1564,7 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
if (rc) {
dprintk("RPC: %s: failed ib_post_send for register,"
" status %i\n", __func__, rc);
- while (i--)
- rpcrdma_unmap_one(ia, --seg);
+ goto out_err;
} else {
seg1->mr_rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
seg1->mr_base = seg1->mr_dma + pageoff;
@@ -1574,6 +1572,10 @@ rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
seg1->mr_len = len;
}
*nsegs = i;
+ return 0;
+out_err:
+ while (i--)
+ rpcrdma_unmap_one(ia, --seg);
return rc;