Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=3168b0780d06ace875696f8a648d04d6089654e5
Commit:     3168b0780d06ace875696f8a648d04d6089654e5
Parent:     b524fe646c9a226a847e30ca1221dc22e952f16b
Author:     Satyam Sharma <[EMAIL PROTECTED]>
AuthorDate: Tue May 8 09:18:58 2007 +0100
Committer:  Steven Whitehouse <[EMAIL PROTECTED]>
CommitDate: Mon Jul 9 08:22:10 2007 +0100

    [DLM] fix a couple of races
    
    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 <[EMAIL PROTECTED]>
    Signed-off-by: David Teigland <[EMAIL PROTECTED]>
    Signed-off-by: Steven Whitehouse <[EMAIL PROTECTED]>
---
 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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