Re: [PATCH 1/2] tracing: Have futex syscall trace event show specific user data

[Peter Zijlstra]

On Tue, Mar 03, 2026 at 04:47:36PM -0500, Steven Rostedt wrote:
> From: Steven Rostedt <rostedt@xxxxxxxxxxx>
> 
> Add specific reporting of the futex system call. This allows for debugging
> the futex code a bit easier. Instead of just showing the values passed
> into the futex system call, read the value of the user space memory
> pointed to by the addr parameter.
> 
> Also make the op parameter more readable by parsing the values to show
> what the command is:
> 
>  futex_requeue_p-3251    [002] .....  2101.068479: sys_futex(uaddr: 0x55e79a4da834 (0x80000cb1), FUTEX_LOCK_PI|FUTEX_PRIVATE_FLAG, val: 0)
>  futex_requeue_p-3248    [001] .....  2101.068970: sys_futex(uaddr: 0x7f859072f990 (0xcb2), FUTEX_WAIT_BITSET|FUTEX_CLOCK_REALTIME, val: 3250)
>  futex_requeue_p-3252    [005] .....  2101.069108: sys_futex(uaddr: 0x55e79a4da838 (0), FUTEX_WAIT_REQUEUE_PI|FUTEX_PRIVATE_FLAG, val: 0, timespec: 0x7ffe61076aa0, uaddr2: 0x55e79a4da834, uaddr2: 94453214586932, val3: 0)
>  futex_requeue_p-3252    [005] .....  2101.069410: sys_futex(uaddr: 0x55e79a4da834 (0x80000cb1), FUTEX_LOCK_PI|FUTEX_PRIVATE_FLAG, val: 0)
> 
> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> ---
>  kernel/trace/trace_syscalls.c | 266 +++++++++++++++++++++++++++++++++-
>  1 file changed, 263 insertions(+), 3 deletions(-)

Egads, I really dislike how all sorts of syscall crud is 'duplicated' in
this file, rather than near or in the actual syscall definition.