From 1b2f121c1418249e56048d816754b479b3cb6fb3 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 25 Jun 2014 10:39:46 -0400 Subject: ftrace-graph: Remove dependency of ftrace_stop() from ftrace_graph_stop() ftrace_stop() is going away as it disables parts of function tracing that affects users that should not be affected. But ftrace_graph_stop() is built on ftrace_stop(). Here's another example of killing all of function tracing because something went wrong with function graph tracing. Instead of disabling all users of function tracing on function graph error, disable only function graph tracing. A new function is created called ftrace_graph_is_dead(). This is called in strategic paths to prevent function graph from doing more harm and allowing at least a warning to be printed before the system crashes. NOTE: ftrace_stop() is still used until all the archs are converted over to use ftrace_graph_is_dead(). After that, ftrace_stop() will be removed. Reviewed-by: Masami Hiramatsu Cc: Frederic Weisbecker Signed-off-by: Steven Rostedt --- kernel/trace/trace_functions_graph.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'kernel/trace/trace_functions_graph.c') diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 4de3e57f723..3604690be70 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -15,6 +15,38 @@ #include "trace.h" #include "trace_output.h" +static bool kill_ftrace_graph; + +/** + * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called + * + * ftrace_graph_stop() is called when a severe error is detected in + * the function graph tracing. This function is called by the critical + * paths of function graph to keep those paths from doing any more harm. + */ +bool ftrace_graph_is_dead(void) +{ + return kill_ftrace_graph; +} + +/** + * ftrace_graph_stop - set to permanently disable function graph tracincg + * + * In case of an error int function graph tracing, this is called + * to try to keep function graph tracing from causing any more harm. + * Usually this is pretty severe and this is called to try to at least + * get a warning out to the user. + */ +void ftrace_graph_stop(void) +{ + kill_ftrace_graph = true; + /* + * ftrace_stop() will be removed when all archs are updated to + * use ftrace_graph_is_dead() + */ + ftrace_stop(); +} + /* When set, irq functions will be ignored */ static int ftrace_graph_skip_irqs; @@ -92,6 +124,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, unsigned long long calltime; int index; + if (unlikely(ftrace_graph_is_dead())) + return -EBUSY; + if (!current->ret_stack) return -EBUSY; -- cgit v1.2.3-70-g09d2 From 545d47b8f359f7e9b5beabc28bfeecb3fc6af1ee Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 25 Jun 2014 11:13:27 -0400 Subject: ftrace-graph: Remove usage of ftrace_stop() in ftrace_graph_stop() All archs now use ftrace_graph_is_dead() to stop function graph tracing. Remove the usage of ftrace_stop() as that is no longer needed. Cc: Frederic Weisbecker Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt --- kernel/trace/trace_functions_graph.c | 5 ----- 1 file changed, 5 deletions(-) (limited to 'kernel/trace/trace_functions_graph.c') diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 3604690be70..2c944e6c4a9 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -40,11 +40,6 @@ bool ftrace_graph_is_dead(void) void ftrace_graph_stop(void) { kill_ftrace_graph = true; - /* - * ftrace_stop() will be removed when all archs are updated to - * use ftrace_graph_is_dead() - */ - ftrace_stop(); } /* When set, irq functions will be ignored */ -- cgit v1.2.3-70-g09d2 From 6508fa761c330a1d2b4ae36199d08dbcb70e3ddb Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Fri, 18 Jul 2014 15:17:27 +0400 Subject: tracing: let user specify tracing_thresh after selecting function_graph Currently, tracing_thresh works only if we specify it before selecting function_graph tracer. If we do the opposite, tracing_thresh will change it's value, but it will not be applied. To fix it, we add update_thresh callback which is called whenever tracing_thresh is updated and for function_graph tracer we register handler which reinitializes tracer depending on tracing_thresh. Link: http://lkml.kernel.org/p/20140718111727.GA3206@stfomichev-desktop.yandex.net Signed-off-by: Stanislav Fomichev Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 65 ++++++++++++++++++++++++++++++++---- kernel/trace/trace.h | 2 ++ kernel/trace/trace_functions_graph.c | 7 ++++ 3 files changed, 67 insertions(+), 7 deletions(-) (limited to 'kernel/trace/trace_functions_graph.c') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4a343db45d4..2752147ed31 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4201,10 +4201,9 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf, } static ssize_t -tracing_max_lat_read(struct file *filp, char __user *ubuf, - size_t cnt, loff_t *ppos) +tracing_nsecs_read(unsigned long *ptr, char __user *ubuf, + size_t cnt, loff_t *ppos) { - unsigned long *ptr = filp->private_data; char buf[64]; int r; @@ -4216,10 +4215,9 @@ tracing_max_lat_read(struct file *filp, char __user *ubuf, } static ssize_t -tracing_max_lat_write(struct file *filp, const char __user *ubuf, - size_t cnt, loff_t *ppos) +tracing_nsecs_write(unsigned long *ptr, const char __user *ubuf, + size_t cnt, loff_t *ppos) { - unsigned long *ptr = filp->private_data; unsigned long val; int ret; @@ -4232,6 +4230,52 @@ tracing_max_lat_write(struct file *filp, const char __user *ubuf, return cnt; } +static ssize_t +tracing_thresh_read(struct file *filp, char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + return tracing_nsecs_read(&tracing_thresh, ubuf, cnt, ppos); +} + +static ssize_t +tracing_thresh_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + struct trace_array *tr = filp->private_data; + int ret; + + mutex_lock(&trace_types_lock); + ret = tracing_nsecs_write(&tracing_thresh, ubuf, cnt, ppos); + if (ret < 0) + goto out; + + if (tr->current_trace->update_thresh) { + ret = tr->current_trace->update_thresh(tr); + if (ret < 0) + goto out; + } + + ret = cnt; +out: + mutex_unlock(&trace_types_lock); + + return ret; +} + +static ssize_t +tracing_max_lat_read(struct file *filp, char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + return tracing_nsecs_read(filp->private_data, ubuf, cnt, ppos); +} + +static ssize_t +tracing_max_lat_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + return tracing_nsecs_write(filp->private_data, ubuf, cnt, ppos); +} + static int tracing_open_pipe(struct inode *inode, struct file *filp) { struct trace_array *tr = inode->i_private; @@ -5133,6 +5177,13 @@ static int snapshot_raw_open(struct inode *inode, struct file *filp) #endif /* CONFIG_TRACER_SNAPSHOT */ +static const struct file_operations tracing_thresh_fops = { + .open = tracing_open_generic, + .read = tracing_thresh_read, + .write = tracing_thresh_write, + .llseek = generic_file_llseek, +}; + static const struct file_operations tracing_max_lat_fops = { .open = tracing_open_generic, .read = tracing_max_lat_read, @@ -6494,7 +6545,7 @@ static __init int tracer_init_debugfs(void) init_tracer_debugfs(&global_trace, d_tracer); trace_create_file("tracing_thresh", 0644, d_tracer, - &tracing_thresh, &tracing_max_lat_fops); + &global_trace, &tracing_thresh_fops); trace_create_file("README", 0444, d_tracer, NULL, &tracing_readme_fops); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 9258f5a815d..385391fb1d3 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -339,6 +339,7 @@ struct tracer_flags { * @reset: called when one switches to another tracer * @start: called when tracing is unpaused (echo 1 > tracing_enabled) * @stop: called when tracing is paused (echo 0 > tracing_enabled) + * @update_thresh: called when tracing_thresh is updated * @open: called when the trace file is opened * @pipe_open: called when the trace_pipe file is opened * @close: called when the trace file is released @@ -357,6 +358,7 @@ struct tracer { void (*reset)(struct trace_array *tr); void (*start)(struct trace_array *tr); void (*stop)(struct trace_array *tr); + int (*update_thresh)(struct trace_array *tr); void (*open)(struct trace_iterator *iter); void (*pipe_open)(struct trace_iterator *iter); void (*close)(struct trace_iterator *iter); diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 2c944e6c4a9..74d98820497 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -475,6 +475,12 @@ static void graph_trace_reset(struct trace_array *tr) unregister_ftrace_graph(); } +int graph_trace_update_thresh(struct trace_array *tr) +{ + graph_trace_reset(tr); + return graph_trace_init(tr); +} + static int max_bytes_for_cpu; static enum print_line_t @@ -1525,6 +1531,7 @@ static struct trace_event graph_trace_ret_event = { static struct tracer graph_trace __tracer_data = { .name = "function_graph", + .update_thresh = graph_trace_update_thresh, .open = graph_trace_open, .pipe_open = graph_trace_open, .close = graph_trace_close, -- cgit v1.2.3-70-g09d2 From ba1afef6a47c4133831fefcad4e0d7bf1d0ee99e Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Fri, 18 Jul 2014 18:07:49 -0400 Subject: tracing: Convert local function_graph functions to static Local functions should be static. Reported-by: kbuild test robot Signed-off-by: Steven Rostedt --- kernel/trace/trace_functions_graph.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/trace/trace_functions_graph.c') diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 74d98820497..f0a0c982cde 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -353,7 +353,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace) return ret; } -int trace_graph_thresh_entry(struct ftrace_graph_ent *trace) +static int trace_graph_thresh_entry(struct ftrace_graph_ent *trace) { if (tracing_thresh) return 1; @@ -442,7 +442,7 @@ void set_graph_array(struct trace_array *tr) smp_mb(); } -void trace_graph_thresh_return(struct ftrace_graph_ret *trace) +static void trace_graph_thresh_return(struct ftrace_graph_ret *trace) { if (tracing_thresh && (trace->rettime - trace->calltime < tracing_thresh)) @@ -475,7 +475,7 @@ static void graph_trace_reset(struct trace_array *tr) unregister_ftrace_graph(); } -int graph_trace_update_thresh(struct trace_array *tr) +static int graph_trace_update_thresh(struct trace_array *tr) { graph_trace_reset(tr); return graph_trace_init(tr); @@ -1435,7 +1435,7 @@ static void __print_graph_headers_flags(struct seq_file *s, u32 flags) seq_printf(s, " | | | |\n"); } -void print_graph_headers(struct seq_file *s) +static void print_graph_headers(struct seq_file *s) { print_graph_headers_flags(s, tracer_flags.val); } -- cgit v1.2.3-70-g09d2