STRUCT W1_MASTER(9)

👑 struct w1_master(9) 👑

okay so welcome to the Kernel API Manual, bestie — this entry is all about struct w1_master, and the whole vibe is literally one per bus master. no cap.

🌸 NAME 🌸

struct w1_master — one per bus master. that's it, that's the energy. icon.

✨ SYNOPSIS ✨

here's the full struct, no skipping, no summarizing, we respect the whole thing:

struct w1_master {
    struct list_head        w1_master_entry;
    struct module           *owner;
    unsigned char           name[W1_MAXNAMELEN];
    struct mutex            list_mutex;
    struct list_head        slist;
    struct list_head        async_list;
    int max_slave_count, slave_count;
    unsigned long           attempts;
    int slave_ttl;
    int initialized;
    u32 id;
    int search_count;
    u64 search_id;
    atomic_t refcnt;
    void *priv;
    int enable_pullup;
    int pullup_duration;
    long flags;
    struct task_struct      *thread;
    struct mutex            mutex;
    struct mutex            bus_mutex;
    struct device_driver    *driver;
    struct device           dev;
    struct w1_bus_master    *bus_master;
    u32 seq;
 };

🧚 Members 🧚

okay so every member, one by one, because we do not leave the group chat on read:

• w1_master_entry — the master linked list. it's giving linked-list energy.
• owner — the module owner.
• name — a dynamically allocated bus name.
• list_mutex — protects slist and async_list.
• slist — the linked list of slaves.
• async_list — the linked list of netlink commands to execute.
• max_slave_count — the maximum number of slaves to search for at a time.
• slave_count — the current number of slaves known.
• attempts — the number of searches run.
• slave_ttl — the number of searches before a slave is timed out.
• initialized — prevents init/removal race conditions.
• id — the w1 bus number.
• search_count — the number of automatic searches to run; -1 means unlimited.
• search_id — allows continuing a search.
• refcnt — the reference count.
• priv — private data storage.
• enable_pullup — allows a strong pullup.
• pullup_duration — the time for the next strong pullup.
• flags — one of w1_master_flags.
• thread — the thread for bus search and netlink commands.
• mutex — protects most of w1_master.
• bus_mutex — protects concurrent bus access (the page says pretect, iconic typo, same meaning tho).
• driver — the sysfs driver.
• dev — the sysfs device.
• bus_master — the I/O operations available.
• seq — the sequence number used for netlink broadcasts.

💫 SEE ALSO 💫

go look at these too, bestie — the kernel file is ./include/linux/w1.h, and the whole friend group is:

• struct w1_reg_num(9)
• struct w1_slave(9)
• struct w1_bus_master(9)
• enum w1_master_flags(9)
• struct w1_family_ops(9)
• struct w1_family(9)
• module_w1_family(9)

xoxo, source/version ./include/linux, dated October 2026 — byeee bestie, slay responsibly 💅💖