[lustre-devel] [PATCH 06/22] lnet: tidy lnet_discover and fix mem accounting bug.
James Simmons
jsimmons at infradead.org
Tue Jun 2 17:59:45 PDT 2020
From: Mr NeilBrown <neilb at suse.de>
A recent patch introduce a memory accounting bug because "n_ids"
can change between the ALLOC call and the FREE call.
With this patch we fix that by ensuring n_ids doesn't change - the
current change is not needed.
Also:
- discard 'max_intf' var. It is always exactly lnet_interfaces_max,
so just use that directly.
- only copy back the number of interfaces found
- report the number of interfaces actually copied.
- Move the copy_to_user until after all locks and references are
dropped so there is no need to re-take any locks.
WC-bug-id: https://jira.whamcloud.com/browse/LU-9679
Lustre-commit: 45722de60a8fb ("LU-9679 lnet: tidy lnet_discover and fix mem accounting bug.")
Signed-off-by: Mr NeilBrown <neilb at suse.de>
Reviewed-on: https://review.whamcloud.com/38644
Reviewed-by: Shaun Tancheff <shaun.tancheff at hpe.com>
Reviewed-by: Chris Horn <chris.horn at hpe.com>
Reviewed-by: Oleg Drokin <green at whamcloud.com>
Signed-off-by: James Simmons <jsimmons at infradead.org>
---
net/lnet/lnet/api-ni.c | 28 ++++++++++------------------
1 file changed, 10 insertions(+), 18 deletions(-)
diff --git a/net/lnet/lnet/api-ni.c b/net/lnet/lnet/api-ni.c
index e2c364b..629a597 100644
--- a/net/lnet/lnet/api-ni.c
+++ b/net/lnet/lnet/api-ni.c
@@ -4163,7 +4163,6 @@ static int lnet_ping(struct lnet_process_id id, signed long timeout,
int cpt;
int i;
int rc;
- int max_intf = lnet_interfaces_max;
if (n_ids <= 0 ||
id.nid == LNET_NID_ANY)
@@ -4172,11 +4171,11 @@ static int lnet_ping(struct lnet_process_id id, signed long timeout,
if (id.pid == LNET_PID_ANY)
id.pid = LNET_PID_LUSTRE;
- /* if the user buffer has more space than the max_intf
- * then only fill it up to max_intf
+ /* If the user buffer has more space than the lnet_interfaces_max,
+ * then only fill it up to lnet_interfaces_max.
*/
- if (n_ids > max_intf)
- n_ids = max_intf;
+ if (n_ids > lnet_interfaces_max)
+ n_ids = lnet_interfaces_max;
buf = kcalloc(n_ids, sizeof(*buf), GFP_KERNEL);
if (!buf)
@@ -4204,11 +4203,6 @@ static int lnet_ping(struct lnet_process_id id, signed long timeout,
if (rc)
goto out_decref;
- /* Peer may have changed. */
- lp = lpni->lpni_peer_net->lpn_peer;
- if (lp->lp_nnis < n_ids)
- n_ids = lp->lp_nnis;
-
i = 0;
p = NULL;
while ((p = lnet_get_next_peer_ni_locked(lp, NULL, p)) != NULL) {
@@ -4217,20 +4211,18 @@ static int lnet_ping(struct lnet_process_id id, signed long timeout,
if (++i >= n_ids)
break;
}
+ rc = i;
- lnet_net_unlock(cpt);
-
- rc = -EFAULT;
- if (copy_to_user(ids, buf, n_ids * sizeof(*buf)))
- goto out_relock;
- rc = n_ids;
-out_relock:
- lnet_net_lock(cpt);
out_decref:
lnet_peer_ni_decref_locked(lpni);
out:
lnet_net_unlock(cpt);
+
+ if (rc >= 0)
+ if (copy_to_user(ids, buf, rc * sizeof(*buf)))
+ rc = -EFAULT;
kfree(buf);
+
return rc;
}
--
1.8.3.1
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