gsm_control_retransmit(9)

💖 gsm_control_retransmit 💖

okay so bestie, we're in the Kernel API Manual today and the star of the show is gsm_control_retransmit(9) — literally the "oops did that control frame get lost, lemme send it again" girlie. sit down, grab a strawberry drink 🍓, and let's get into it.

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✨ NAME ✨

gsm_control_retransmit — retransmit a control frame 🫶

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🌸 SYNOPSIS 🌸

void gsm_control_retransmit (struct timer_list *t );

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

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🎀 ARGUMENTS 🎀

• t — the timer that's contained in our gsm object ⏰

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🦋 DESCRIPTION 🦋

so here's the vibe: this gets called off the T2 timer expiry, and its whole job is to retransmit control frames that have been lost in the system somewhere 😭 like genuinely lost, gone, ghosted.

The control_lock protects us from colliding with another sender or a receive completion event — it's giving bodyguard energy ngl 🔥

⚠️ but bestie, hear me: in that situation the timer may still occur in a small window, but gsm->pending_cmd will be NULL and we just let the timer expire. no drama, no crash, we simply let it go 💀

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👑 SEE ALSO 👑

the kernel file is ./drivers/tty/n_gsm.c and honestly the whole friend group is here — every single one, no cap:

• gsm_fcs_add(9)
• gsm_fcs_add_block(9)
• gsm_read_ea(9)
• gsm_read_ea_val(9)
• gsm_encode_modem(9)
• gsm_encode_params(9)
• gsm_register_devices(9)
• gsm_unregister_devices(9)
• gsm_print_packet(9)
• gsm_stuff_frame(9)
• gsm_send(9)
• gsm_dlci_clear_queues(9)
• gsm_response(9)
• gsm_command(9)
• gsm_data_alloc(9)
• gsm_send_packet(9)
• gsm_is_flow_ctrl_msg(9)
• gsm_data_kick(9)
• __gsm_data_queue(9)
• gsm_data_queue(9)
• gsm_dlci_data_output(9)
• gsm_dlci_data_output_framed(9)
• gsm_dlci_modem_output(9)
• gsm_dlci_data_sweep(9)
• gsm_dlci_data_kick(9)
• gsm_control_command(9)
• gsm_control_reply(9)
• gsm_process_modem(9)
• gsm_process_negotiation(9)
• gsm_control_modem(9)
• gsm_control_negotiation(9)
• gsm_control_rls(9)
• gsm_control_message(9)
• gsm_control_response(9)
• gsm_control_keep_alive(9)
• gsm_control_transmit(9)
• gsm_control_send(9)
• gsm_control_wait(9)
• gsm_dlci_close(9)
• gsm_dlci_open(9)
• gsm_dlci_negotiate(9)
• gsm_dlci_t1(9)
• gsm_dlci_begin_open(9)
• gsm_dlci_set_opening(9)
• gsm_dlci_set_wait_config(9)
• gsm_dlci_begin_close(9)
• gsm_dlci_data(9)
• gsm_dlci_command(9)
• gsm_kick_timer(9)
• gsm_dlci_copy_config_values(9)
• gsm_dlci_config(9)
• gsm_dlci_alloc(9)
• gsm_dlci_free(9)
• gsm_dlci_release(9)
• gsm_queue(9)
• gsm0_receive_state_check_and_fix(9)
• gsm0_receive(9)
• gsm1_receive_state_check_and_fix(9)
• gsm1_receive(9)
• gsm_error(9)
• gsm_cleanup_mux(9)
• gsm_activate_mux(9)
• gsm_free_mux(9)
• gsm_free_muxr(9)
• gsm_alloc_mux(9)
• gsmld_output(9)
• gsmld_write_trigger(9)
• gsmld_write_task(9)
• gsmld_attach_gsm(9)
• gsmld_detach_gsm(9)
• gsmld_flush_buffer(9)
• gsmld_close(9)
• gsmld_open(9)
• gsmld_write_wakeup(9)
• gsmld_read(9)
• gsmld_write(9)
• gsmld_poll(9)
• gsm_modem_upd_via_data(9)
• gsm_modem_upd_via_msc(9)
• gsm_modem_update(9)
• gsm_wait_modem_change(9)

like, the way this list ate and left no crumbs 🌈 go read them all iykyk 💜

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sign-off time 🧚✨

this little masterpiece lives in ./drivers/tty, dated October 2026, and it's gsm_control_retransmit(9) through and through. mwah 💋 go retransmit those frames bestie, periodt 💅🎀