ftrace_regex_open(9)

💅 ftrace_regex_open(9) — Kernel API Manual ✨

okay so this is the Kernel API Manual page for ftrace_regex_open(9), and it's giving "tiny setup function with main character energy" 🎀 bestie, let's get into it.

🌸 NAME 🌸

ftrace_regex_open — initialize function tracer filter files. 💖

✨ SYNOPSIS ✨

int ftrace_regex_open (struct trace_array *tr , struct ftrace_ops *ops ,
int flag , struct inode *inode , struct file *file );

🎀 ARGUMENTS 🎀

• tr — the trace_array that holds the ftrace_ops [optional]. 🫶
• ops — the ftrace_ops that hold the hash filters [optional]. 🌸
• flag — the type of filter to process. 🔥
• inode — the inode, usually passed in to your open routine. 🎀
• file — the file, usually passed in to your open routine. 🎀

🦋 DESCRIPTION 🦋

Okay so ftrace_regex_open initializes the filter files for ops. Depending on flag, it may process the filter hash or the notrace hash of ops. 🦋

With this called from the open routine, you can use ftrace_filter_write for the write routine if flag has FTRACE_ITER_FILTER set, or ftrace_notrace_write if flag has FTRACE_ITER_NOTRACE set. tracing_lseek should be used as the lseek routine, and release must call ftrace_regex_release. 💅

Note, bestie: if tr is not NULL, its reference has to be taken before ops may be referenced. If ops is NULL and tr is not, then tr->ops is used. If tr is NULL and ops is not, then ops->private is used for tr. If both tr and ops are NULL, then the global_ops is to be used, and tr will be the global_ops.private pointer. 🫶

⭐ RETURN ⭐

0 on success or a negative errno value on failure. That's the whole contract, no cap. ✨

🌈 SEE ALSO 🌈

Kernel file: ./kernel/trace/ftrace.c. Here's the whole cross-reference lineup, fr fr:

• 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)
• 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_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)

---

made with 💖 from source/version ./kernel/trace, dated October 2026, for page ftrace_regex_open(9). 🎀