Fix compile error on kernel 3.0.101 with CONFIG_PERF_EVENTS

[lttng-modules.git] / lttng-statedump-impl.c

diff --git a/lttng-statedump-impl.c b/lttng-statedump-impl.c
index 17b02faf2be564385ff3c2bd5b7a210ef77988d8..cf92aa44689a4587cc6ab4f0cd4cd441f4abb71b 100644 (file)
--- a/lttng-statedump-impl.c
+++ b/lttng-statedump-impl.c
@@ -390,6 +390,9 @@ int lttng_list_interrupts(struct lttng_session *session)
 }
 #endif
 
+/*
+ * Called with task lock held.
+ */
 static
 void lttng_statedump_process_ns(struct lttng_session *session,
                struct task_struct *p,
@@ -401,8 +404,20 @@ void lttng_statedump_process_ns(struct lttng_session *session,
        struct nsproxy *proxy;
        struct pid_namespace *pid_ns;
 
+       /*
+        * Back and forth on locking strategy within Linux upstream for nsproxy.
+        * See Linux upstream commit 728dba3a39c66b3d8ac889ddbe38b5b1c264aec3
+        * "namespaces: Use task_lock and not rcu to protect nsproxy"
+        * for details.
+        */
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) || \
+               LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
+               LTTNG_UBUNTU_KERNEL_RANGE(3,16,0,11, 3,17,0,0))
+       proxy = p->nsproxy;
+#else
        rcu_read_lock();
        proxy = task_nsproxy(p);
+#endif
        if (proxy) {
                pid_ns = lttng_get_proxy_pid_ns(proxy);
                do {
@@ -414,7 +429,13 @@ void lttng_statedump_process_ns(struct lttng_session *session,
                trace_lttng_statedump_process_state(session,
                        p, type, mode, submode, status, NULL);
        }
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) || \
+               LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
+               LTTNG_UBUNTU_KERNEL_RANGE(3,16,0,11, 3,17,0,0))
+       /* (nothing) */
+#else
        rcu_read_unlock();
+#endif
 }
 
 static