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authorPavel Emelyanov <xemul@openvz.org>2007-12-04 00:45:06 -0800
committerDavid S. Miller <davem@sunset.davemloft.net>2007-12-05 05:37:27 -0800
commit4ac63ad6c52e9cdefbcb54ec4575ab12b78b49d9 (patch)
treee8ff9d5a9bbe01c68a95f71f1707cc24afa770d1 /net/ipv4
parenta014bc8f0f0a3a0cac4fef656f101cdfb77b71eb (diff)
[IPVS]: Fix sched registration race when checking for name collision.
The register_ip_vs_scheduler() checks for the scheduler with the same name under the read-locked __ip_vs_sched_lock, then drops, takes it for writing and puts the scheduler in list. This is racy, since we can have a race window between the lock being re-locked for writing. The fix is to search the scheduler with the given name right under the write-locked __ip_vs_sched_lock. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Simon Horman <horms@verge.net.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ipvs/ip_vs_sched.c27
1 files changed, 14 insertions, 13 deletions
diff --git a/net/ipv4/ipvs/ip_vs_sched.c b/net/ipv4/ipvs/ip_vs_sched.c
index 1602304abbf..43223586190 100644
--- a/net/ipv4/ipvs/ip_vs_sched.c
+++ b/net/ipv4/ipvs/ip_vs_sched.c
@@ -183,19 +183,6 @@ int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
/* increase the module use count */
ip_vs_use_count_inc();
- /*
- * Make sure that the scheduler with this name doesn't exist
- * in the scheduler list.
- */
- sched = ip_vs_sched_getbyname(scheduler->name);
- if (sched) {
- ip_vs_scheduler_put(sched);
- ip_vs_use_count_dec();
- IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
- "already existed in the system\n", scheduler->name);
- return -EINVAL;
- }
-
write_lock_bh(&__ip_vs_sched_lock);
if (scheduler->n_list.next != &scheduler->n_list) {
@@ -207,6 +194,20 @@ int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler)
}
/*
+ * Make sure that the scheduler with this name doesn't exist
+ * in the scheduler list.
+ */
+ list_for_each_entry(sched, &ip_vs_schedulers, n_list) {
+ if (strcmp(scheduler->name, sched->name) == 0) {
+ write_unlock_bh(&__ip_vs_sched_lock);
+ ip_vs_use_count_dec();
+ IP_VS_ERR("register_ip_vs_scheduler(): [%s] scheduler "
+ "already existed in the system\n",
+ scheduler->name);
+ return -EINVAL;
+ }
+ }
+ /*
* Add it into the d-linked scheduler list
*/
list_add(&scheduler->n_list, &ip_vs_schedulers);