_ctl_diag_release(9)

💅 _ctl_diag_release(9) — the Kernel API Manual page you didn't know you needed 🎀

okay so bestie, welcome to the Kernel API Manual, and today's main character is _ctl_diag_release(9). it's a tiny little function with a big job and i'm obsessed. let's get into it ✨

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🌸 NAME 🌸

_ctl_diag_release — request to send Diag Release Message to firmware

like, that's the whole vibe. it asks the firmware to release the diag buffer. slay. 💅

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🦋 SYNOPSIS 🦋

long _ctl_diag_release (struct MPT3SAS_ADAPTER *ioc , void __user *arg
);

yes bestie, that's the signature, character for character, no notes. it returns a long, it takes an ioc and an arg. that's it, that's the whole door. 🚪

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🎀 ARGUMENTS 🎀

• ioc — the manpage just says ? here, and honestly? relatable. we don't have extra deets, so i'm not gonna make any up. the mystery stays a mystery. 🕵️‍♀️
• arg — user space buffer containing ioctl content. that's the actual documented tea, right there. 🍵

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💖 DESCRIPTION 💖

so what does this icon actually do? it lets ownership of the specified buffer be returned to the driver. which means — and this is the important part — an application can then read the buffer without fear that firmware is overwriting information in the buffer. no race-y nightmare, no "why is my data changing under me" moment, just clean reading energy. 🧚

firmware out here doing the most, and this function is the one that says "okay bestie, hands off the buffer, we're reading now." periodt. 👑

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🌈 SEE ALSO 🌈

okay this list is LONG, but every single one is here because we do not skip the boring parts in this house. go read them, they're all (9) kernel API pages, iykyk.

first up, the kernel file: ./drivers/scsi/mpt3sas/mpt3sas_ctl.c, and then:

• enum block_state(9), _ctl_display_some_debug(9), mpt3sas_ctl_done(9), _ctl_check_event_type(9), mpt3sas_ctl_add_to_event_log(9), mpt3sas_ctl_event_callback(9), _ctl_verify_adapter(9)
• mpt3sas_ctl_pre_reset_handler(9), mpt3sas_ctl_clear_outstanding_ioctls(9), mpt3sas_ctl_reset_done_handler(9), _ctl_fasync(9), _ctl_poll(9), _ctl_set_task_mid(9)
• _ctl_send_mctp_passthru_req(9), _ctl_do_mpt_command(9), _ctl_getiocinfo(9), _ctl_eventquery(9), _ctl_eventenable(9), _ctl_eventreport(9), _ctl_do_reset(9)
• _ctl_btdh_search_sas_device(9), _ctl_btdh_search_pcie_device(9), _ctl_btdh_search_raid_device(9), _ctl_btdh_mapping(9)
• _ctl_diag_capability(9), _ctl_diag_get_bufftype(9), _ctl_diag_register_2(9), mpt3sas_enable_diag_buffer(9), _ctl_diag_register(9), _ctl_diag_unregister(9), _ctl_diag_query(9), mpt3sas_send_diag_release(9), _ctl_diag_read_buffer(9), _ctl_addnl_diag_query(9), _ctl_enable_diag_sbr_reload(9)
• _ctl_compat_mpt_command(9), _ctl_ioctl_main(9), _ctl_get_mpt_mctp_passthru_adapter(9), mpt3sas_get_device_count(9), _ctl_ioctl(9), _ctl_mpt2_ioctl(9), _ctl_ioctl_compat(9), _ctl_mpt2_ioctl_compat(9)
• version_fw_show(9), version_bios_show(9), version_mpi_show(9), version_product_show(9), version_nvdata_persistent_show(9), version_nvdata_default_show(9)
• board_name_show(9), board_assembly_show(9), board_tracer_show(9), io_delay_show(9), device_delay_show(9), fw_queue_depth_show(9), host_sas_address_show(9), logging_level_show(9), fwfault_debug_show(9), ioc_reset_count_show(9), reply_queue_count_show(9), BRM_status_show(9)
• host_trace_buffer_size_show(9), host_trace_buffer_show(9), host_trace_buffer_enable_show(9)
• diag_trigger_master_show(9), diag_trigger_master_store(9), diag_trigger_event_show(9), diag_trigger_event_store(9), diag_trigger_scsi_show(9), diag_trigger_scsi_store(9), diag_trigger_mpi_show(9), diag_trigger_mpi_store(9)
• drv_support_bitmap_show(9), enable_sdev_max_qd_show(9), enable_sdev_max_qd_store(9)
• sas_address_show(9), sas_device_handle_show(9), sas_ncq_prio_supported_show(9), sas_ncq_prio_enable_show(9)
• mpt3sas_ctl_init(9), mpt3sas_ctl_release(9), mpt3sas_ctl_exit(9)

that's the whole crew. no cap, every last one is in there. 🫶

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heads up bestie: nothing in this page is marked dangerous, deprecated or undefined — it's just the ownership handoff described above, exactly as written. don't go reading extra behaviour into it, okay? 🙈

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🌸 that's the page! this one lives over in ./drivers/scsi/mpt3sas, dated October 2026, and it's filed under _ctl_diag_release(9). mwah, go read a buffer safely, ily. 💜🎀