Messages in this thread Patch in this message | | | From | Steven Whitehouse <> | Subject | [PATCH 2/4] [DLM] fix a couple of races | Date | Mon, 18 Jun 2007 15:54:28 +0100 |
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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> --- fs/dlm/config.c | 15 +++++++++++---- 1 files changed, 11 insertions(+), 4 deletions(-)diff --git a/fs/dlm/config.c b/fs/dlm/config.c index 822abdc..5a3d390 100644 --- a/fs/dlm/config.c +++ b/fs/dlm/config.c @@ -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; }
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