[Apologies for multiple resends, formatting issue]
Hi Steven, Thanks for taking a look. This sample module is dependent on - - commit: f45d122 tracing: Kernel access to Ftrace instances - Patches pending review: https://lore.kernel.org/lkml/[email protected]/ I mentioned it in the cover page, but will add to this patch as well to avoid confusion. So, I think the messages you are seeing is due to the absence of Patches pending review: https://lore.kernel.org/lkml/[email protected]/ Let me know if you prefer to have the sample module and this patch-set (pending review) as part of one patch set. For reference, adding the cover page details here - ------------------------------------------------------------------------------------------------------------------ This patch is for a sample module to demonstrate the use of APIs that were introduced/exported in order to access Ftrace instances from within the kernel. Please Note: This module is dependent on - - commit: f45d122 tracing: Kernel access to Ftrace instances - Patches pending review: https://lore.kernel.org/lkml/[email protected]/ The sample module creates/lookup a trace array called sample-instance on module load time. We then start a kernel thread(simple-thread) to - 1) Enable tracing for event "sample_event" to buffer associated with the trace array - "sample-instance". 2) Start a timer that will disable tracing to this buffer after 5 sec. (Tracing disabled after 5 sec ie at count=4) 3) Write to the buffer using trace_array_printk() 4) Stop the kernel thread and destroy the buffer during module unload. A sample output for the same - # tracer: nop # # entries-in-buffer/entries-written: 16/16 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | sample-instance-26797 [003] .... 955180.489833: simple_thread: trace_array_printk: count=0 sample-instance-26797 [003] .... 955180.489836: sample_event: count value=0 at jiffies=5249940864 sample-instance-26797 [003] .... 955181.513722: simple_thread: trace_array_printk: count=1 sample-instance-26797 [003] .... 955181.513724: sample_event: count value=1 at jiffies=5249941888 sample-instance-26797 [003] .... 955182.537629: simple_thread: trace_array_printk: count=2 sample-instance-26797 [003] .... 955182.537631: sample_event: count value=2 at jiffies=5249942912 sample-instance-26797 [003] .... 955183.561516: simple_thread: trace_array_printk: count=3 sample-instance-26797 [003] .... 955183.561518: sample_event: count value=3 at jiffies=5249943936 sample-instance-26797 [003] .... 955184.585423: simple_thread: trace_array_printk: count=4 sample-instance-26797 [003] .... 955184.585427: sample_event: count value=4 at jiffies=5249944960 sample-instance-26797 [003] .... 955185.609344: simple_thread: trace_array_printk: count=5 sample-instance-26797 [003] .... 955186.633241: simple_thread: trace_array_printk: count=6 sample-instance-26797 [003] .... 955187.657157: simple_thread: trace_array_printk: count=7 sample-instance-26797 [003] .... 955188.681039: simple_thread: trace_array_printk: count=8 sample-instance-26797 [003] .... 955189.704937: simple_thread: trace_array_printk: count=9 sample-instance-26797 [003] .... 955190.728840: simple_thread: trace_array_printk: count=10 -------------------------------------------------------------------------------------------------------------------- Thanks, Divya On 10/15/19 10:05 AM, Steven Rostedt wrote:
On Fri, 20 Sep 2019 16:59:26 -0700 Divya Indi <[email protected]> wrote:This is a sample module to demostrate the use of the newly introduced and exported APIs to access Ftrace instances from within the kernel. Newly introduced APIs used here - 1. Create a new trace array if it does not exist. struct trace_array *trace_array_create(const char *name) 2. Destroy/Remove a trace array. int trace_array_destroy(struct trace_array *tr) 3. Lookup a trace array, given its name. struct trace_array *trace_array_lookup(const char *name) 4. Enable/Disable trace events: int trace_array_set_clr_event(struct trace_array *tr, const char *system, const char *event, int set); Exported APIs - 1. trace_printk equivalent for instances. int trace_array_printk(struct trace_array *tr, unsigned long ip, const char *fmt, ...); 2. Helper function. void trace_printk_init_buffers(void); 3. To decrement the reference counter. void trace_array_put(struct trace_array *tr) Signed-off-by: Divya Indi <[email protected]> Reviewed-by: Manjunath Patil <[email protected]> Reviewed-by: Joe Jin <[email protected]> --- samples/Kconfig | 7 ++ samples/Makefile | 1 + samples/ftrace_instance/Makefile | 6 ++ samples/ftrace_instance/sample-trace-array.c | 134 +++++++++++++++++++++++++++ samples/ftrace_instance/sample-trace-array.h | 84 +++++++++++++++++ 5 files changed, 232 insertions(+) create mode 100644 samples/ftrace_instance/Makefile create mode 100644 samples/ftrace_instance/sample-trace-array.c create mode 100644 samples/ftrace_instance/sample-trace-array.hI applied this patch but get this: /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘mytimer_handler’: /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:35:2: error: implicit declaration of function ‘trace_array_set_clr_event’; did you mean ‘trace_set_clr_event’? [-Werror=implicit-function-declaration] trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", 0); ^~~~~~~~~~~~~~~~~~~~~~~~~ trace_set_clr_event /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘simple_thread_func’: /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:47:2: error: implicit declaration of function ‘trace_array_printk’; did you mean ‘trace_seq_printf’? [-Werror=implicit-function-declaration] trace_array_printk(tr, _THIS_IP_, "trace_array_printk: count=%d\n", ^~~~~~~~~~~~~~~~~~ trace_seq_printf /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘simple_thread’: /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:85:2: error: implicit declaration of function ‘trace_array_put’; did you mean ‘trace_seq_putc’? [-Werror=implicit-function-declaration] trace_array_put(tr); ^~~~~~~~~~~~~~~ trace_seq_putc /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘sample_trace_array_init’: /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:100:7: error: implicit declaration of function ‘trace_array_lookup’; did you mean ‘radix_tree_lookup’? [-Werror=implicit-function-declaration] tr = trace_array_lookup("sample-instance"); ^~~~~~~~~~~~~~~~~~ radix_tree_lookup /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:100:5: warning: assignment to ‘struct trace_array *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion] tr = trace_array_lookup("sample-instance"); ^ /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:102:8: error: implicit declaration of function ‘trace_array_create’; did you mean ‘ftrace_force_update’? [-Werror=implicit-function-declaration] tr = trace_array_create("sample-instance"); ^~~~~~~~~~~~~~~~~~ ftrace_force_update /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:102:6: warning: assignment to ‘struct trace_array *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion] tr = trace_array_create("sample-instance"); ^ /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:110:2: error: implicit declaration of function ‘trace_printk_init_buffers’; did you mean ‘trace_event_get_offsets’? [-Werror=implicit-function-declaration] trace_printk_init_buffers(); ^~~~~~~~~~~~~~~~~~~~~~~~~ trace_event_get_offsets /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘sample_trace_array_exit’: /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:126:2: error: implicit declaration of function ‘trace_array_destroy’; did you mean ‘assoc_array_destroy’? [-Werror=implicit-function-declaration] trace_array_destroy(tr); ^~~~~~~~~~~~~~~~~~~ assoc_array_destroy cc1: some warnings being treated as errors make[3]: *** [/work/git/linux-trace.git/scripts/Makefile.build:266: samples/ftrace_instance/sample-trace-array.o] Error 1 make[2]: *** [/work/git/linux-trace.git/scripts/Makefile.build:509: samples/ftrace_instance] Error 2 make[1]: *** [/work/git/linux-trace.git/Makefile:1650: samples] Error 2 make[1]: *** Waiting for unfinished jobs.... -- Steve
