ftrace_set_filter(9)

✨ ftrace_set_filter(9) ✨

okay bestie, welcome to the ftrace_set_filter page 💅 this is straight out of the Kernel API Manual, and it's literally the glow-up you need to understand function filtering in ftrace. no cap.

---

🌸 NAME 🌸

ftrace_set_filter — set a function to filter on in ftrace 🎀

---

✨ SYNOPSIS ✨

int ftrace_set_filter (struct ftrace_ops *ops , unsigned char *buf , int
len , int reset );

---

🦋 ARGUMENTS 🦋

• ops — the ops you're setting the filter with, bestie. this is the main character here 👑
• buf — the string that holds the function filter text ✍️
• len — the length of that string, fr fr
• reset — non-zero to reset all the filters before applying this filter. like a full clear before the new aesthetic 💀

---

💖 DESCRIPTION 💖

Filters denote which functions should be enabled when tracing is enabled. that's the whole vibe — they decide who gets to show up to the party 🎉

If buf is NULL and reset is set, all functions will be enabled for tracing. everyone's invited, no guest list, no drama 🫶

⚠️ okay important: this can allocate memory which must be freed before ops can be freed — either by removing each filtered addr or by using ftrace_free_filter(ops). don't leave that memory hanging, it's giving bad manners 😭

---

🌈 SEE ALSO 🌈

Kernel file ./kernel/trace/ftrace.c, plus the whole squad:

ftrace_lookup_ip(9), ftrace_free_filter(9), ftrace_hash_move(9), ftrace_location_range(9), ftrace_location(9), ftrace_text_reserved(9), ftrace_bug(9), ftrace_update_record(9), ftrace_test_record(9), ftrace_get_addr_new(9), ftrace_get_addr_curr(9), ftrace_rec_iter_start(9), ftrace_rec_iter_next(9), ftrace_rec_iter_record(9), ftrace_run_stop_machine(9), arch_ftrace_update_code(9), ftrace_startup_subops(9), ftrace_shutdown_subops(9), ftrace_regex_open(9), allocate_ftrace_func_mapper(9), ftrace_func_mapper_find_ip(9), ftrace_func_mapper_add_ip(9), ftrace_func_mapper_remove_ip(9), free_ftrace_func_mapper(9), register_ftrace_direct(9), unregister_ftrace_direct(9), modify_ftrace_direct_nolock(9), modify_ftrace_direct(9), hash_add(9), update_ftrace_direct_add(9), hash_sub(9), update_ftrace_direct_del(9), update_ftrace_direct_mod(9), ftrace_set_filter_ip(9), ftrace_set_filter_ips(9), ftrace_ops_set_global_filter(9), ftrace_set_notrace(9), ftrace_set_global_filter(9), ftrace_set_global_notrace(9), ftrace_ops_get_func(9), ftrace_kill(9), ftrace_is_dead(9), register_ftrace_function(9), unregister_ftrace_function(9), ftrace_lookup_symbols(9)

---

and that's the whole page, bestie 🧚💜 this one lives in ./kernel/trace and it's stamped October 2026 — go forth and filter your functions responsibly, ily, mwah 🍓💅