+++ /dev/null
-From 8a56d7761d2d041ae5e8215d20b4167d8aa93f51 Mon Sep 17 00:00:00 2001
-From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
-Date: Mon, 25 Nov 2013 20:59:46 -0500
-Subject: ftrace: Fix function graph with loading of modules
-
-From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
-
-commit 8a56d7761d2d041ae5e8215d20b4167d8aa93f51 upstream.
-
-Commit 8c4f3c3fa9681 "ftrace: Check module functions being traced on reload"
-fixed module loading and unloading with respect to function tracing, but
-it missed the function graph tracer. If you perform the following
-
- # cd /sys/kernel/debug/tracing
- # echo function_graph > current_tracer
- # modprobe nfsd
- # echo nop > current_tracer
-
-You'll get the following oops message:
-
- ------------[ cut here ]------------
- WARNING: CPU: 2 PID: 2910 at /linux.git/kernel/trace/ftrace.c:1640 __ftrace_hash_rec_update.part.35+0x168/0x1b9()
- Modules linked in: nfsd exportfs nfs_acl lockd ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables uinput snd_hda_codec_idt
- CPU: 2 PID: 2910 Comm: bash Not tainted 3.13.0-rc1-test #7
- Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
- 0000000000000668 ffff8800787efcf8 ffffffff814fe193 ffff88007d500000
- 0000000000000000 ffff8800787efd38 ffffffff8103b80a 0000000000000668
- ffffffff810b2b9a ffffffff81a48370 0000000000000001 ffff880037aea000
- Call Trace:
- [<ffffffff814fe193>] dump_stack+0x4f/0x7c
- [<ffffffff8103b80a>] warn_slowpath_common+0x81/0x9b
- [<ffffffff810b2b9a>] ? __ftrace_hash_rec_update.part.35+0x168/0x1b9
- [<ffffffff8103b83e>] warn_slowpath_null+0x1a/0x1c
- [<ffffffff810b2b9a>] __ftrace_hash_rec_update.part.35+0x168/0x1b9
- [<ffffffff81502f89>] ? __mutex_lock_slowpath+0x364/0x364
- [<ffffffff810b2cc2>] ftrace_shutdown+0xd7/0x12b
- [<ffffffff810b47f0>] unregister_ftrace_graph+0x49/0x78
- [<ffffffff810c4b30>] graph_trace_reset+0xe/0x10
- [<ffffffff810bf393>] tracing_set_tracer+0xa7/0x26a
- [<ffffffff810bf5e1>] tracing_set_trace_write+0x8b/0xbd
- [<ffffffff810c501c>] ? ftrace_return_to_handler+0xb2/0xde
- [<ffffffff811240a8>] ? __sb_end_write+0x5e/0x5e
- [<ffffffff81122aed>] vfs_write+0xab/0xf6
- [<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85
- [<ffffffff81122dbd>] SyS_write+0x59/0x82
- [<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85
- [<ffffffff8150a2d2>] system_call_fastpath+0x16/0x1b
- ---[ end trace 940358030751eafb ]---
-
-The above mentioned commit didn't go far enough. Well, it covered the
-function tracer by adding checks in __register_ftrace_function(). The
-problem is that the function graph tracer circumvents that (for a slight
-efficiency gain when function graph trace is running with a function
-tracer. The gain was not worth this).
-
-The problem came with ftrace_startup() which should always be called after
-__register_ftrace_function(), if you want this bug to be completely fixed.
-
-Anyway, this solution moves __register_ftrace_function() inside of
-ftrace_startup() and removes the need to call them both.
-
-Reported-by: Dave Wysochanski <dwysocha@redhat.com>
-Fixes: ed926f9b35cd ("ftrace: Use counters to enable functions to trace")
-Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- kernel/trace/ftrace.c | 64 +++++++++++++++++++++++++++-----------------------
- 1 file changed, 35 insertions(+), 29 deletions(-)
-
---- a/kernel/trace/ftrace.c
-+++ b/kernel/trace/ftrace.c
-@@ -312,9 +312,6 @@ static int remove_ftrace_list_ops(struct
-
- static int __register_ftrace_function(struct ftrace_ops *ops)
- {
-- if (ftrace_disabled)
-- return -ENODEV;
--
- if (FTRACE_WARN_ON(ops == &global_ops))
- return -EINVAL;
-
-@@ -348,9 +345,6 @@ static int __unregister_ftrace_function(
- {
- int ret;
-
-- if (ftrace_disabled)
-- return -ENODEV;
--
- if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)))
- return -EBUSY;
-
-@@ -1940,10 +1934,15 @@ static void ftrace_startup_enable(int co
- static int ftrace_startup(struct ftrace_ops *ops, int command)
- {
- bool hash_enable = true;
-+ int ret;
-
- if (unlikely(ftrace_disabled))
- return -ENODEV;
-
-+ ret = __register_ftrace_function(ops);
-+ if (ret)
-+ return ret;
-+
- ftrace_start_up++;
- command |= FTRACE_UPDATE_CALLS;
-
-@@ -1965,12 +1964,17 @@ static int ftrace_startup(struct ftrace_
- return 0;
- }
-
--static void ftrace_shutdown(struct ftrace_ops *ops, int command)
-+static int ftrace_shutdown(struct ftrace_ops *ops, int command)
- {
- bool hash_disable = true;
-+ int ret;
-
- if (unlikely(ftrace_disabled))
-- return;
-+ return -ENODEV;
-+
-+ ret = __unregister_ftrace_function(ops);
-+ if (ret)
-+ return ret;
-
- ftrace_start_up--;
- /*
-@@ -2005,9 +2009,10 @@ static void ftrace_shutdown(struct ftrac
- }
-
- if (!command || !ftrace_enabled)
-- return;
-+ return 0;
-
- ftrace_run_update_code(command);
-+ return 0;
- }
-
- static void ftrace_startup_sysctl(void)
-@@ -2873,16 +2878,13 @@ static void __enable_ftrace_function_pro
- if (i == FTRACE_FUNC_HASHSIZE)
- return;
-
-- ret = __register_ftrace_function(&trace_probe_ops);
-- if (!ret)
-- ret = ftrace_startup(&trace_probe_ops, 0);
-+ ret = ftrace_startup(&trace_probe_ops, 0);
-
- ftrace_probe_registered = 1;
- }
-
- static void __disable_ftrace_function_probe(void)
- {
-- int ret;
- int i;
-
- if (!ftrace_probe_registered)
-@@ -2895,9 +2897,7 @@ static void __disable_ftrace_function_pr
- }
-
- /* no more funcs left */
-- ret = __unregister_ftrace_function(&trace_probe_ops);
-- if (!ret)
-- ftrace_shutdown(&trace_probe_ops, 0);
-+ ftrace_shutdown(&trace_probe_ops, 0);
-
- ftrace_probe_registered = 0;
- }
-@@ -3948,12 +3948,15 @@ device_initcall(ftrace_nodyn_init);
- static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
- static inline void ftrace_startup_enable(int command) { }
- /* Keep as macros so we do not need to define the commands */
--# define ftrace_startup(ops, command) \
-- ({ \
-- (ops)->flags |= FTRACE_OPS_FL_ENABLED; \
-- 0; \
-+# define ftrace_startup(ops, command) \
-+ ({ \
-+ int ___ret = __register_ftrace_function(ops); \
-+ if (!___ret) \
-+ (ops)->flags |= FTRACE_OPS_FL_ENABLED; \
-+ ___ret; \
- })
--# define ftrace_shutdown(ops, command) do { } while (0)
-+# define ftrace_shutdown(ops, command) __unregister_ftrace_function(ops)
-+
- # define ftrace_startup_sysctl() do { } while (0)
- # define ftrace_shutdown_sysctl() do { } while (0)
-
-@@ -4326,9 +4329,7 @@ int register_ftrace_function(struct ftra
- if (unlikely(ftrace_disabled))
- goto out_unlock;
-
-- ret = __register_ftrace_function(ops);
-- if (!ret)
-- ret = ftrace_startup(ops, 0);
-+ ret = ftrace_startup(ops, 0);
-
-
- out_unlock:
-@@ -4348,9 +4349,7 @@ int unregister_ftrace_function(struct ft
- int ret;
-
- mutex_lock(&ftrace_lock);
-- ret = __unregister_ftrace_function(ops);
-- if (!ret)
-- ftrace_shutdown(ops, 0);
-+ ret = ftrace_shutdown(ops, 0);
- mutex_unlock(&ftrace_lock);
-
- return ret;
-@@ -4544,6 +4543,13 @@ ftrace_suspend_notifier_call(struct noti
- return NOTIFY_DONE;
- }
-
-+/* Just a place holder for function graph */
-+static struct ftrace_ops fgraph_ops __read_mostly = {
-+ .func = ftrace_stub,
-+ .flags = FTRACE_OPS_FL_STUB | FTRACE_OPS_FL_GLOBAL |
-+ FTRACE_OPS_FL_RECURSION_SAFE,
-+};
-+
- int register_ftrace_graph(trace_func_graph_ret_t retfunc,
- trace_func_graph_ent_t entryfunc)
- {
-@@ -4570,7 +4576,7 @@ int register_ftrace_graph(trace_func_gra
- ftrace_graph_return = retfunc;
- ftrace_graph_entry = entryfunc;
-
-- ret = ftrace_startup(&global_ops, FTRACE_START_FUNC_RET);
-+ ret = ftrace_startup(&fgraph_ops, FTRACE_START_FUNC_RET);
-
- out:
- mutex_unlock(&ftrace_lock);
-@@ -4587,7 +4593,7 @@ void unregister_ftrace_graph(void)
- ftrace_graph_active--;
- ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
- ftrace_graph_entry = ftrace_graph_entry_stub;
-- ftrace_shutdown(&global_ops, FTRACE_STOP_FUNC_RET);
-+ ftrace_shutdown(&fgraph_ops, FTRACE_STOP_FUNC_RET);
- unregister_pm_notifier(&ftrace_suspend_notifier);
- unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
-
projects / thirdparty / kernel / stable-queue.git / commitdiff
