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ceph: don't reference req after put

PATCH In review Alex Elder 2 participants 2 messages Nov 29, 2012 Ceph common code (libceph)

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Alex Elder

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#0 lore raw

PATCH 1/1 ceph: don't reference req after put

In __unregister_request(), there is a call to list_del_init() referencing a request that was the subject of a call to ceph_osdc_put_request() on the previous line. This is not safe, because the request structure could have been freed by the time we reach the list_del_init().

Fix this by reversing the order of these lines.

Signed-off-by Alex Elder <[email protected]>
---
 net/ceph/osd_client.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
net/ceph/osd_client.c +0 -0
index 9b6f0e4..d1177ec 100644
@@ -797,9 +797,9 @@ static void __unregister_request(struct

ceph_osd_client *osdc,
req->r_osd = NULL;
}

+ list_del_init(&req->r_req_lru_item);
ceph_osdc_put_request(req);

- list_del_init(&req->r_req_lru_item);
if (osdc->num_requests == 0) {
dout(" no requests, canceling timeout\n"); __cancel_osd_timeout(osdc);

Signature · 1 line
1.7.9.5
Reviewed-by on v1 1/1
#1 lore raw
Reviewed-by Sage Weil <[email protected]>
Quoted 38 lines · Alex Elder

In __unregister_request(), there is a call to list_del_init() referencing a request that was the subject of a call to ceph_osdc_put_request() on the previous line. This is not safe, because the request structure could have been freed by the time we reach the list_del_init().

Fix this by reversing the order of these lines.

Signed-off-by Alex Elder <[email protected]>
---
 net/ceph/osd_client.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
net/ceph/osd_client.c +1 -1
index 9b6f0e4..d1177ec 100644
@@ -797,9 +797,9 @@ static void __unregister_request(struct
 ceph_osd_client *osdc,
 			req->r_osd = NULL;
 	}
 
+	list_del_init(&req->r_req_lru_item);
 	ceph_osdc_put_request(req);
 
-	list_del_init(&req->r_req_lru_item);
 	if (osdc->num_requests == 0) {
 		dout(" no requests, canceling timeout\n");

__cancel_osd_timeout(osdc);

Signature · 6 lines
1.7.9.5

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