Messages in this thread Patch in this message | | | From | Divya Indi <> | Subject | [PATCH 5/5] tracing: New functions for kernel access to Ftrace instances | Date | Wed, 14 Aug 2019 10:55:27 -0700 |
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Adding 2 new functions - 1) trace_array_lookup : Look up and return a trace array, given its name. 2) trace_array_set_clr_event : Enable/disable event recording to the given trace array.
NOTE: trace_array_lookup returns a trace array and also increments the reference counter associated with the returned trace array. Make sure to call trace_array_put() once the use is done so that the instance can be removed at a later time.
Example use:
tr = trace_array_lookup("foo-bar"); if (!tr) tr = trace_array_create("foo-bar"); // Log to tr // Enable/disable events to tr trace_array_set_clr_event(tr, _THIS_IP,"system","event",1);
// Done using tr trace_array_put(tr); ..
Also, use trace_array_set_clr_event to enable/disable events to a trace array. So now we no longer need to have ftrace_set_clr_event as an exported API.
Signed-off-by: Divya Indi <divya.indi@oracle.com> --- include/linux/trace.h | 2 ++ include/linux/trace_events.h | 3 ++- kernel/trace/trace.c | 28 ++++++++++++++++++++++++++++ kernel/trace/trace_events.c | 23 ++++++++++++++++++++++- 4 files changed, 54 insertions(+), 2 deletions(-)
diff --git a/include/linux/trace.h b/include/linux/trace.h index 2c782d5..05164bb 100644 --- a/include/linux/trace.h +++ b/include/linux/trace.h @@ -32,6 +32,8 @@ int trace_array_printk(struct trace_array *tr, unsigned long ip, struct trace_array *trace_array_create(const char *name); int trace_array_destroy(struct trace_array *tr); void trace_array_put(struct trace_array *tr); +struct trace_array *trace_array_lookup(const char *name); + #endif /* CONFIG_TRACING */ #endif /* _LINUX_TRACE_H */ diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 8a62731..05a7514 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -540,7 +540,8 @@ extern int trace_define_field(struct trace_event_call *call, const char *type, #define is_signed_type(type) (((type)(-1)) < (type)1) int trace_set_clr_event(const char *system, const char *event, int set); - +int trace_array_set_clr_event(struct trace_array *tr, const char *system, + const char *event, int set); /* * The double __builtin_constant_p is because gcc will give us an error * if we try to allocate the static variable to fmt if it is not a diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 7b6a37a..e394d55 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8514,6 +8514,34 @@ static int instance_rmdir(const char *name) return ret; } +/** + * trace_array_lookup - Lookup the trace array, given its name. + * @name: The name of the trace array to be looked up. + * + * Lookup and return the trace array associated with @name. + * + * NOTE: The reference counter associated with the returned trace array is + * incremented to ensure it is not freed when in use. Make sure to call + * "trace_array_put" for this trace array when its use is done. + */ +struct trace_array *trace_array_lookup(const char *name) +{ + struct trace_array *tr; + + mutex_lock(&trace_types_lock); + + list_for_each_entry(tr, &ftrace_trace_arrays, list) { + if (tr->name && strcmp(tr->name, name) == 0) { + tr->ref++; + mutex_unlock(&trace_types_lock); + return tr; + } + } + mutex_unlock(&trace_types_lock); + return NULL; +} +EXPORT_SYMBOL_GPL(trace_array_lookup); + static __init void create_trace_instances(struct dentry *d_tracer) { trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer, diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 2621995..96dd997 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -834,7 +834,6 @@ static int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set) return ret; } -EXPORT_SYMBOL_GPL(ftrace_set_clr_event); /** * trace_set_clr_event - enable or disable an event @@ -859,6 +858,28 @@ int trace_set_clr_event(const char *system, const char *event, int set) } EXPORT_SYMBOL_GPL(trace_set_clr_event); +/** + * trace_array_set_clr_event - enable or disable an event for a trace array + * @system: system name to match (NULL for any system) + * @event: event name to match (NULL for all events, within system) + * @set: 1 to enable, 0 to disable + * + * This is a way for other parts of the kernel to enable or disable + * event recording to instances. + * + * Returns 0 on success, -EINVAL if the parameters do not match any + * registered events. + */ +int trace_array_set_clr_event(struct trace_array *tr, const char *system, + const char *event, int set) +{ + if (!tr) + return -ENOENT; + + return __ftrace_set_clr_event(tr, NULL, system, event, set); +} +EXPORT_SYMBOL_GPL(trace_array_set_clr_event); + /* 128 should be much more than enough */ #define EVENT_BUF_SIZE 127 -- 1.8.3.1
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