STRUCT SSH_RTL(9)

🌸 struct ssh_rtl(9) — SSH request transport layer, bestie edition 🌸

okay so this is a page from the Kernel API Manual, and honestly? It's a struct page, which means it's basically a little tour of a data structure's inner life. No cap. Stick with me and we'll go through every single field together, because the way that this thing is laid out is lowkey iconic 💅

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✨ NAME ✨

struct ssh_rtl — the SSH request transport layer. That's the whole vibe. It's the struct that handles getting SSH requests from here to there. 🦋

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🎀 SYNOPSIS 🎀

here's the actual shape of it, verbatim, no edits from me:

struct ssh_rtl {
    struct ssh_ptl ptl;
    unsigned long state;
    struct {
      spinlock_t lock;
      struct list_head head;
    } queue;
    struct {
      spinlock_t lock;
      struct list_head head;
      atomic_t count;
    } pending;
    struct {
      struct work_struct work;
    } tx;
    struct {
      spinlock_t lock;
      ktime_t timeout;
      ktime_t expires;
      struct delayed_work reaper;
    } rtx_timeout;
    struct ssh_rtl_ops ops;
 };

look at those nested anonymous structs. she's got structure, she's got layers. main character energy fr fr 👑

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💖 Members 💖

every member, one by one, no skipping, we do not leave anyone out in this house 🫶

• ptl — the underlying packet transport layer. Like, this is the layer under this layer. Layers on layers on layers. It's giving onion 🧅
• state — the state(-flags) of the transport layer. Flags! Plural-ish! Keeping track of where things are at ✨
• queue — the request submission queue. The lineup. The waiting room. The "you're on the list" zone.
  • queue.lock — the lock for modifying the request submission queue. You wanna touch the queue, you take the lock first. Manners 💅
  • queue.head — the list-head of the request submission queue. Head of the line, literally.
• pending — the set/list of pending requests. Everything that's still cooking 🍓
  • pending.lock — the lock for modifying the request set. Same energy, different list.
  • pending.head — the list-head of the pending set/list. Again: head of the line. We love consistency.
  • pending.count — the number of currently pending requests. An actual tally. We're counting, bestie 🔢
• tx — the transmitter subsystem. The send-it side of things 📤
  • tx.work — the transmitter work item. That's the actual unit of work that does the transmitting.
• rtx_timeout — the retransmission timeout subsystem. Yes, rtx is retransmission. Yes, it's a whole subsystem. She's got her own little world in here ⏰
  • rtx_timeout.lock — the lock for modifying the retransmission timeout reaper. (the reaper!! spooky but make it kernel 🌈)
  • rtx_timeout.timeout — the timeout interval for retransmission. How long we wait before we go "hmm, maybe again?"
  • rtx_timeout.expires — the time specifying when the reaper work is next scheduled. A little calendar entry for the reaper.
  • rtx_timeout.reaper — the work performing timeout checks and subsequent actions. It checks. It acts. It's the reaper. Obsessed 😭
• ops — the request layer operations. The function-pointer crew. The queeroes, if you will 💜

real talk: none of these fields are optional reading. If you're touching ssh_rtl you need to know what each one does, and now you do. slay.

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/platform/surface/aggregator/ssh_request_layer.h
• enum ssh_rtl_state_flags(9)
• struct ssh_rtl_ops(9)
• ssh_rtl_get_device(9)
• ssh_request_rtl(9)

like, go read those too. iykyk 🧚

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and that's the whole page, bestie 💖 this one came out of ./drivers/platform/surface/agg... (yes, truncated, that's how the page does it, don't come for me) and it's dated October 2026 — so it's a struct page from the future, which is very main character of it. periodt. 🎀✨