STRUCT LINEREQ(9)

✨ NAME ✨

okay so bestie, meet struct linereq(9) from the Kernel API Manual — it's literally the struct that contains the state of a userspace line request. no cap, it's giving main-character energy for your GPIO line request lore. 💅

🌸 SYNOPSIS 🌸

here's the exact shape of this cutie, bestie — field names and all, copy them character for character:

struct linereq {
    struct gpio_device *gdev;
    const char *label;
    u32 num_lines;
    wait_queue_head_t wait;
    struct notifier_block device_unregistered_nb;
    u32 event_buffer_size;
    struct gpio_v2_line_event *events;
    atomic_t seqno;
    struct mutex config_mutex;
    struct line lines[];
 };

🫶 Members 🫶

• gdev — the GPIO device that this line request is all about. 💖
• label — the consumer label, aka the little tag used to tag GPIO descriptors. 🎀
• num_lines — the number of lines in the lines array. ✨
• wait — the wait queue that handles blocking reads of events. 🦋
• device_unregistered_nb — the notifier block for receiving gdev unregister events. 👑
• event_buffer_size — the number of elements allocated in events. 🌸
• events — the KFIFO for the GPIO events. 🔥
• seqno — the sequence number for edge events generated on all lines in this line request. heads up though: this is not used when num_lines is 1, because the line_seqno is then the same and it's cheaper to calculate. 💀
• config_mutex — the mutex for serializing ioctl calls to ensure consistency of configuration, particularly those multi-step accesses to desc flags. 🫶
• lines — the lines held by this line request, with num_lines elements. 💜

🔥 SEE ALSO 🔥

• Kernel file ./drivers/gpio/gpiolib-cdev.c
• struct linehandle_state(9)
• struct line(9)
• struct lineevent_state(9)
• gpio_chrdev_open(9)
• gpio_chrdev_release(9)

mwah 💋 — this one comes from ./drivers/gpio, October 2026, and yes bestie, it's literally struct linereq(9). 🧚