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Subject[PATCH 08/19] staging/lustre/o2iblnd: connection refcount fix for kiblnd_post_rx
Date
From: Liang Zhen <liang.zhen@intel.com>

kiblnd_post_rx() can't refer to rx::rx_conn anymore after
ib_post_recv() because this rx can be polled out by another thread
which may drop this rx and destroy rx::rx_conn.

This patch fixes this issue by taking an extra refcount on connection
before calling ib_post_recv().

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-on: http://review.whamcloud.com/12852
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5678
Reviewed-by: Isaac Huang <he.huang@intel.com>
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
---
drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
index 345ed4d..c0f5682 100644
--- a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
+++ b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
@@ -178,24 +178,28 @@ kiblnd_post_rx(kib_rx_t *rx, int credit)

rx->rx_nob = -1; /* flag posted */

+ /* NB: need an extra reference after ib_post_recv because we don't
+ * own this rx (and rx::rx_conn) anymore, LU-5678.
+ */
+ kiblnd_conn_addref(conn);
rc = ib_post_recv(conn->ibc_cmid->qp, &rx->rx_wrq, &bad_wrq);
- if (rc != 0) {
+ if (unlikely(rc != 0)) {
CERROR("Can't post rx for %s: %d, bad_wrq: %p\n",
libcfs_nid2str(conn->ibc_peer->ibp_nid), rc, bad_wrq);
rx->rx_nob = 0;
}

if (conn->ibc_state < IBLND_CONN_ESTABLISHED) /* Initial post */
- return rc;
+ goto out;

- if (rc != 0) {
+ if (unlikely(rc != 0)) {
kiblnd_close_conn(conn, rc);
kiblnd_drop_rx(rx); /* No more posts for this rx */
- return rc;
+ goto out;
}

if (credit == IBLND_POSTRX_NO_CREDIT)
- return 0;
+ goto out;

spin_lock(&conn->ibc_lock);
if (credit == IBLND_POSTRX_PEER_CREDIT)
@@ -205,7 +209,9 @@ kiblnd_post_rx(kib_rx_t *rx, int credit)
spin_unlock(&conn->ibc_lock);

kiblnd_check_sends(conn);
- return 0;
+out:
+ kiblnd_conn_decref(conn);
+ return rc;
}

static kib_tx_t *
--
2.1.0


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