ftrace: Fix function graph with loading of modules
Commit8c4f3c3fa9"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:ed926f9b35("ftrace: Use counters to enable functions to trace") Cc: stable@vger.kernel.org # 3.0+ Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat)
Steven Rostedt
parent
4e58e54754
commit
8a56d7761d
1 changed files with 35 additions and 29 deletions
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@ -367,9 +367,6 @@ static int remove_ftrace_list_ops(struct ftrace_ops **list,
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static int __register_ftrace_function(struct ftrace_ops *ops)
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{
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if (unlikely(ftrace_disabled))
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return -ENODEV;
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if (FTRACE_WARN_ON(ops == &global_ops))
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return -EINVAL;
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@ -428,9 +425,6 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
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{
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int ret;
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if (ftrace_disabled)
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return -ENODEV;
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if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)))
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return -EBUSY;
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@ -2088,10 +2082,15 @@ static void ftrace_startup_enable(int command)
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static int ftrace_startup(struct ftrace_ops *ops, int command)
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{
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bool hash_enable = true;
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int ret;
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if (unlikely(ftrace_disabled))
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return -ENODEV;
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ret = __register_ftrace_function(ops);
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if (ret)
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return ret;
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ftrace_start_up++;
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command |= FTRACE_UPDATE_CALLS;
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@ -2113,12 +2112,17 @@ static int ftrace_startup(struct ftrace_ops *ops, int command)
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return 0;
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}
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static void ftrace_shutdown(struct ftrace_ops *ops, int command)
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static int ftrace_shutdown(struct ftrace_ops *ops, int command)
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{
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bool hash_disable = true;
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int ret;
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if (unlikely(ftrace_disabled))
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return;
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return -ENODEV;
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ret = __unregister_ftrace_function(ops);
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if (ret)
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return ret;
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ftrace_start_up--;
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/*
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@ -2153,9 +2157,10 @@ static void ftrace_shutdown(struct ftrace_ops *ops, int command)
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}
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if (!command || !ftrace_enabled)
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return;
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return 0;
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ftrace_run_update_code(command);
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return 0;
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}
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static void ftrace_startup_sysctl(void)
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@ -3060,8 +3065,6 @@ static void __enable_ftrace_function_probe(void)
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if (i == FTRACE_FUNC_HASHSIZE)
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return;
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ret = __register_ftrace_function(&trace_probe_ops);
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if (!ret)
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ret = ftrace_startup(&trace_probe_ops, 0);
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ftrace_probe_registered = 1;
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@ -3069,7 +3072,6 @@ static void __enable_ftrace_function_probe(void)
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static void __disable_ftrace_function_probe(void)
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{
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int ret;
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int i;
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if (!ftrace_probe_registered)
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@ -3082,8 +3084,6 @@ static void __disable_ftrace_function_probe(void)
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}
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/* no more funcs left */
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ret = __unregister_ftrace_function(&trace_probe_ops);
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if (!ret)
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ftrace_shutdown(&trace_probe_ops, 0);
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ftrace_probe_registered = 0;
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@ -4368,10 +4368,13 @@ static inline void ftrace_startup_enable(int command) { }
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/* Keep as macros so we do not need to define the commands */
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# define ftrace_startup(ops, command) \
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({ \
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int ___ret = __register_ftrace_function(ops); \
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if (!___ret) \
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(ops)->flags |= FTRACE_OPS_FL_ENABLED; \
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0; \
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___ret; \
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})
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# define ftrace_shutdown(ops, command) do { } while (0)
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# define ftrace_shutdown(ops, command) __unregister_ftrace_function(ops)
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# define ftrace_startup_sysctl() do { } while (0)
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# define ftrace_shutdown_sysctl() do { } while (0)
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@ -4780,8 +4783,6 @@ int register_ftrace_function(struct ftrace_ops *ops)
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mutex_lock(&ftrace_lock);
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ret = __register_ftrace_function(ops);
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if (!ret)
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ret = ftrace_startup(ops, 0);
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mutex_unlock(&ftrace_lock);
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@ -4801,9 +4802,7 @@ int unregister_ftrace_function(struct ftrace_ops *ops)
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int ret;
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mutex_lock(&ftrace_lock);
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ret = __unregister_ftrace_function(ops);
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if (!ret)
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ftrace_shutdown(ops, 0);
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ret = ftrace_shutdown(ops, 0);
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mutex_unlock(&ftrace_lock);
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return ret;
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@ -4997,6 +4996,13 @@ ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
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return NOTIFY_DONE;
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}
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/* Just a place holder for function graph */
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static struct ftrace_ops fgraph_ops __read_mostly = {
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.func = ftrace_stub,
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.flags = FTRACE_OPS_FL_STUB | FTRACE_OPS_FL_GLOBAL |
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FTRACE_OPS_FL_RECURSION_SAFE,
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};
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int register_ftrace_graph(trace_func_graph_ret_t retfunc,
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trace_func_graph_ent_t entryfunc)
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{
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@ -5023,7 +5029,7 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
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ftrace_graph_return = retfunc;
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ftrace_graph_entry = entryfunc;
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ret = ftrace_startup(&global_ops, FTRACE_START_FUNC_RET);
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ret = ftrace_startup(&fgraph_ops, FTRACE_START_FUNC_RET);
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out:
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mutex_unlock(&ftrace_lock);
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@ -5040,7 +5046,7 @@ void unregister_ftrace_graph(void)
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ftrace_graph_active--;
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ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
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ftrace_graph_entry = ftrace_graph_entry_stub;
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ftrace_shutdown(&global_ops, FTRACE_STOP_FUNC_RET);
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ftrace_shutdown(&fgraph_ops, FTRACE_STOP_FUNC_RET);
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unregister_pm_notifier(&ftrace_suspend_notifier);
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unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
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