Upstream-Status: Backport Signed-off-by: Bruce Ashfield From 4ba1f53c5aebb4433fedc25d65af010274985043 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Thu, 21 Aug 2014 10:53:12 -0400 Subject: [PATCH 2/3] Update statedump to 3.17 nsproxy locking This Linux upstream commit introduces locking strategy back and forth: commit 728dba3a39c66b3d8ac889ddbe38b5b1c264aec3 Author: Eric W. Biederman Date: Mon Feb 3 19:13:49 2014 -0800 namespaces: Use task_lock and not rcu to protect nsproxy Use the task lock starting from kernel 3.17 rather than RCU to access the task nsproxy. Signed-off-by: Mathieu Desnoyers --- lttng-statedump-impl.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/lttng-statedump-impl.c b/lttng-statedump-impl.c index dad51ddaa250..e4caa488e436 100644 --- a/lttng-statedump-impl.c +++ b/lttng-statedump-impl.c @@ -378,6 +378,9 @@ 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, @@ -389,8 +392,18 @@ 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)) rcu_read_lock(); proxy = task_nsproxy(p); +#else /* #if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0)) */ + proxy = p->nsproxy; +#endif /* #else #if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0)) */ if (proxy) { pid_ns = lttng_get_proxy_pid_ns(proxy); do { @@ -402,7 +415,9 @@ 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)) rcu_read_unlock(); +#endif /* #if (LINUX_VERSION_CODE < KERNEL_VERSION(3,17,0)) */ } static -- 1.8.1.2