set_trigger_filter(9)

💅 set_trigger_filter(9) — a Kernel API Manual moment ✨

okay so real talk, this is a page from the Kernel API Manual and it's genuinely such a helpful little function. welcome bestie, let's get into it 🫶

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✨ NAME ✨

set_trigger_filter — the Generic event_command @set_filter implementation 👑

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🌸 SYNOPSIS 🌸

int set_trigger_filter (char *filter_str , struct event_trigger_data
*trigger_data , struct trace_event_file *file );

like, that's the whole signature, no notes 💅

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🎀 ARGUMENTS 🎀

• filter_str — the filter string for the trigger, and honestly if you pass NULL it just nukes the filter, bye 👋
• trigger_data — trigger-specific data, iykyk, it's the trigger's own little bag of stuff 🍓
• file — the trace_event_file that's associated with the event, it's giving "which event are we even talking about" energy 🙈

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🦋 DESCRIPTION 🦋

So this is the common implementation for event command filter parsing and filter instantiation — lowkey the whole filter pipeline lives here ✨

Most of the time it's used directly as the set_filter method in event command implementations, like that's just its job and it ate 💅

It's also the one you call to remove a filter, and the way you do that is if filter_str = NULL — periodt, that's the whole removal mechanism 🎀

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🔥 RETURN 🔥

0 on success, errno otherwise 😭 (so like, check your return value bestie, fr fr)

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👑 SEE ALSO 👑

Kernel file ./kernel/trace/trace_events_trigger.c — the source, go read it, it's iconic 📖

And the whole squad, no cap:

• event_triggers_call(9)
• event_triggers_post_call(9)
• event_trigger_count(9)
• event_trigger_print(9)
• event_trigger_init(9)
• event_trigger_free(9)
• clear_event_triggers(9)
• update_cond_flag(9)
• register_trigger(9)
• unregister_trigger(9)
• event_trigger_check_remove(9)
• event_trigger_empty_param(9)
• event_trigger_separate_filter(9)
• trigger_data_alloc(9)
• event_trigger_parse_num(9)
• event_trigger_set_filter(9)
• event_trigger_reset_filter(9)
• event_trigger_register(9)
• event_trigger_unregister(9)
• event_trigger_parse(9)
• find_named_trigger(9)
• is_named_trigger(9)
• save_named_trigger(9)
• del_named_trigger(9)
• pause_named_trigger(9)
• unpause_named_trigger(9)
• set_named_trigger_data(9)

like okay go off, trigger function family reunion 🌈

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this slice of kernel lore comes to you from ./kernel/trace and it's dated October 2026 — catch you in the next one, mwah 💖✨🎀