Re: [PATCH] tracing: tprobe-events: Fix to clean up tprobe correctly when module unload

From: Steven Rostedt
Date: Fri Mar 07 2025 - 12:20:08 EST

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In reply to: Masami Hiramatsu (Google): "[PATCH] tracing: tprobe-events: Fix to clean up tprobe correctly when module unload"
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On Thu, 6 Mar 2025 15:21:44 +0900
"Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote:

> When unloading module, the tprobe events are not correctly cleaned
> up. Thus it becomes `fprobe-event` and never be enabled again even
> if loading the same module again.
>
> For example;
>
> # cd /sys/kernel/tracing
> # modprobe trace_events_sample
> # echo 't:my_tprobe foo_bar' >> dynamic_events
> # cat dynamic_events
> t:tracepoints/my_tprobe foo_bar
> # rmmod trace_events_sample
> # cat dynamic_events
> f:tracepoints/my_tprobe foo_bar
>
> As you can see, the second time my_tprobe starts with 'f' instead
> of 't'.
>
> This cleans up (unregister) the tprobe events when module is
> unloaded.

After applying this, I tried it out:

# cd /sys/kernel/tracing
# modprobe trace_events_sample
# echo 't:my_tprobe foo_bar a=$arg1' > dynamic_events
# echo 1 > events/tracepoints/enable
[wait]
# echo 0 > events/tracepoints/enable
# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 13/13 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
event-sample-1041 [005] ...1. 1957.632897: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1958.656935: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1959.680883: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1960.704855: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1961.728977: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1962.751822: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1963.776834: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1964.800748: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1965.824788: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1966.848789: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1967.872902: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1968.896754: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1969.920737: my_tprobe: (__probestub_foo_bar+0x4/0x20 [trace_events_sample]) a=0xffffffffc006c186
# rmmod trace_events_sample
# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 13/13 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
event-sample-1041 [005] ...1. 1957.632897: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1958.656935: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1959.680883: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1960.704855: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1961.728977: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1962.751822: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1963.776834: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1964.800748: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1965.824788: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1966.848789: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1967.872902: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1968.896754: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1969.920737: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186

# modprobe trace_events_sample
# echo 1 > events/tracepoints/enable
# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 13/13 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
event-sample-1041 [005] ...1. 1957.632897: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1958.656935: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1959.680883: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1960.704855: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1961.728977: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1962.751822: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1963.776834: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1964.800748: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1965.824788: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1966.848789: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1967.872902: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1968.896754: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186
event-sample-1041 [005] ...1. 1969.920737: my_tprobe: (0xffffffffc00620b4) a=0xffffffffc006c186

Tracing doesn't restart.

-- Steve

Next message: Luck, Tony: "RE: [PATCH v4 0/3] mm/hwpoison: Fix regressions in memory failure handling"
Previous message: Florent Revest: "Re: [PATCH] x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodes"
In reply to: Masami Hiramatsu (Google): "[PATCH] tracing: tprobe-events: Fix to clean up tprobe correctly when module unload"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]