rtla: Allow unsetting non-list custom-callback CLI options

libsubcmd implicitly allows the user to unset already set options using
a "no-" prefix for long options. For example, if I set the period like
this:

$ rtla timerlat -D
Loading BPF program
reading osnoise/timerlat_period_us returned 1000
setting osnoise/timerlat_period_us to 1000
reading osnoise/print_stack returned 0
setting osnoise/print_stack to 0
...
<timerlat top>

it can be unset by a subsequent --no-debug:

$ rtla timerlat -D --no-debug
...
<timerlat top>

Currently, this works only for boolean options. Extend the feature for
all options by implementing handling of the "unset" argument in opt_*()
callbacks defined in cli_p.h, except for list options, i.e. options that
can be passed multiple times (--event, --filter, --trigger,
--on-threshold, --on-end).

This allows, for example, unsetting of int/long long options, e.g. "-p":

$ rtla timerlat -D -p100 --no-period
...
setting osnoise/timerlat_period_us to 1000
...

By default, options in params struct are reset to zero. A constant is
added for every parameter with a different default value, which is then
used both in <tool>_hist_args() while setting the initial value and in
opt_*() when unsetting the option. This refactoring ensures there is no
duplicate "magic number".

The default value for opt_llong_callback() and opt_int_callback() is
passed in struct option's defval field; new macros
RTLA_OPT_{LLONG,INT}{,_DEFVAL} are added to define the field
conveniently. The default value for other callbacks is hardcoded inside
each callback's unset logic.

Reviewed-by: Wander Lairson Costa <wander@redhat.com>
Link: https://lore.kernel.org/r/20260629083654.1548925-1-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>

0 files changed, 0 insertions, 0 deletions