> -----Original Message-----
> From: Andrzej Ostruszka <a...@semihalf.com>
> Sent: Monday, April 6, 2020 11:27 PM
> To: Jerin Jacob Kollanukkaran <jer...@marvell.com>; Kiran Kumar Kokkilagadda
> <kirankum...@marvell.com>
> Cc: dev@dpdk.org; tho...@monjalon.net; david.march...@redhat.com;
> m...@ashroe.eu; mattias.ronnb...@ericsson.com; Pavan Nikhilesh
> Bhagavatula <pbhagavat...@marvell.com>; Nithin Kumar Dabilpuram
> <ndabilpu...@marvell.com>; xiao.w.w...@intel.com
> Subject: [EXT] Re: [dpdk-dev] [PATCH v4 03/29] graph: implement node
> operations
>
> External Email
>
> ----------------------------------------------------------------------
> On 4/5/20 10:55 AM, jer...@marvell.com wrote:
> [...]
> > diff --git a/lib/librte_graph/node.c b/lib/librte_graph/node.c index
> > 336cd1c94..d04a0fce0 100644
> > --- a/lib/librte_graph/node.c
> > +++ b/lib/librte_graph/node.c
> [...]
> > +static rte_edge_t
> > +edge_update(struct node *node, struct node *prev, rte_edge_t from,
> > + const char **next_nodes, rte_edge_t nb_edges) {
> > + rte_edge_t i, max_edges, count = 0;
> > + struct node *new_node;
> > + bool need_realloc;
> > + size_t sz;
> > +
> > + if (from == RTE_EDGE_ID_INVALID)
> > + from = node->nb_edges;
> > +
> > + /* Don't create hole in next_nodes[] list */
> > + if (from > node->nb_edges) {
> > + rte_errno = ENOMEM;
> > + goto fail;
> > + }
> > +
> > + /* Remove me from list */
> > + STAILQ_REMOVE(&node_list, node, node, next);
This is where we will remove the node first unconditionally. Later we update
the new node.
> > +
> > + /* Allocate the storage space for new node if required */
> > + max_edges = from + nb_edges;
> > + need_realloc = max_edges > node->nb_edges;
> > + if (need_realloc) {
> > + sz = sizeof(struct node) + (max_edges * RTE_NODE_NAMESIZE);
> > + new_node = realloc(node, sz);
> > + if (new_node == NULL) {
> > + rte_errno = ENOMEM;
> > + goto restore;
> > + } else {
> > + node = new_node;
> > + }
> > + }
> > +
> > + /* Update the new nodes name */
> > + for (i = from; i < max_edges; i++, count++) {
> > + if (rte_strscpy(node->next_nodes[i], next_nodes[count],
> > + RTE_NODE_NAMESIZE) < 0) {
> > + rte_errno = E2BIG;
> > + goto restore;
> > + }
> > + }
> > +restore:
> > + /* Update the linked list to point new node address in prev node */
> > + if (prev)
> > + STAILQ_INSERT_AFTER(&node_list, prev, node, next);
> > + else
> > + STAILQ_INSERT_HEAD(&node_list, node, next);
>
> AFAIU node_list keeps the list of nodes - so I guess you wanted here "replace"
> the old node pointer with the new one. I have not yet seen the usage of this
> function but it seems to me like you unconditionally insert the updated node -
> possibly having node pointer present doubly or with stale pointer. I might be
> missing something here.
>
See above.
> > +
> > + if (need_realloc)
> > + node->nb_edges += max_edges;
>
> It looks to me like this should be simple '='.
>
> > +
> > +fail:
> > + return count;
> > +}
> [...]
> > +rte_edge_t
> > +rte_node_edge_update(rte_node_t id, rte_edge_t from, const char
> **next_nodes,
> > + uint16_t nb_edges)
> > +{
> > + rte_edge_t rc = RTE_EDGE_ID_INVALID;
> > + struct node *n, *prev;
> > +
> > + NODE_ID_CHECK(id);
> > + graph_spinlock_lock();
> > +
> > + prev = NULL;
> > + STAILQ_FOREACH(n, &node_list, next) {
> > + if (n->id == id) {
> > + rc = edge_update(n, prev, from, next_nodes,
> nb_edges);
> > + break;
> > + }
> > + prev = n;
> > + }
>
> OK so in this context my comment above seems to be valid. When we find the id
> we have: prev -> n, we call update() and in there we insert new_node after
> prev
> so we end up with: prev -> n' -> n where n' might be new address for n or
> just n
> when no realloc was performed.
>
> Do I miss anything?
>
See above.
> > +
> > + graph_spinlock_unlock();
> > +fail:
> > + return rc;
> > +}
> > +
> > +static rte_node_t
> > +node_copy_edges(struct node *node, char *next_nodes[]) {
> > + rte_edge_t i;
> > +
> > + for (i = 0; i < node->nb_edges; i++)
> > + next_nodes[i] = node->next_nodes[i];
> > +
> > + return i;
> > +}
> > +
> > +rte_node_t
> > +rte_node_edge_get(rte_node_t id, char *next_nodes[]) {
> > + rte_node_t rc = RTE_NODE_ID_INVALID;
> > + struct node *node;
> > +
> > + NODE_ID_CHECK(id);
> > + graph_spinlock_lock();
> > +
> > + STAILQ_FOREACH(node, &node_list, next) {
> > + if (node->id == id) {
> > + if (next_nodes == NULL)
> > + rc = sizeof(char *) * node->nb_edges;
> > + else
> > + rc = node_copy_edges(node, next_nodes);
>
> Do we want to ready for next_nodes not large enough?
>
> > + break;
> > + }
> > + }
> > +
> > + graph_spinlock_unlock();
> > +fail:
> > + return rc;
> > +}
>
> [...]
>
> With regards
> Andrzej Ostruszka
