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[DLM] fix a couple of races

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Fix two races in fs/dlm/config.c:

(1) Grab the configfs subsystem semaphore before calling
config_group_find_obj() in get_space(). This solves a potential race
between get_space() and concurrent mkdir(2) or rmdir(2).

(2) Grab a reference on the found config_item _while_ holding the configfs
subsystem semaphore in get_comm(), and not after it. This solves a
potential race between get_comm() and concurrent rmdir(2).

Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Satyam Sharma 2007-05-08 09:18:58 +01:00 committed by Steven Whitehouse
parent b524fe646c
commit 3168b0780d
1 changed files with 11 additions and 4 deletions
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15
fs/dlm/config.c
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@ -748,9 +748,16 @@ static ssize_t node_weight_write(struct node *nd, const char *buf, size_t len)
static struct space *get_space(char *name)
{
struct config_item *i;
if (!space_list)
return NULL;
return to_space(config_group_find_obj(space_list, name));
down(&space_list->cg_subsys->su_sem);
i = config_group_find_obj(space_list, name);
up(&space_list->cg_subsys->su_sem);
return to_space(i);
}
static void put_space(struct space *sp)
@ -776,20 +783,20 @@ static struct comm *get_comm(int nodeid, struct sockaddr_storage *addr)
if (cm->nodeid != nodeid)
continue;
found = 1;
config_item_get(i);
break;
} else {
if (!cm->addr_count ||
memcmp(cm->addr[0], addr, sizeof(*addr)))
continue;
found = 1;
config_item_get(i);
break;
}
}
up(&clusters_root.subsys.su_sem);
if (found)
config_item_get(i);
else
if (!found)
cm = NULL;
return cm;
}