STRUCT SRPT_RDMA_CH(9)

💅 struct srpt_rdma_ch(9) — Kernel API Manual, but make it cute ✨

okay so bestie, we're in the kernel API manual today (yes, that manual) and the star of the show is struct srpt_rdma_ch 🎀

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✨ NAME ✨

struct srpt_rdma_ch — literally just an RDMA channel. that's the whole vibe. slay. 💖

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🦋 SYNOPSIS 🦋

here's the whole struct, character for character, no cap — don't touch a single glyph, she's perfect:

struct srpt_rdma_ch {
    struct srpt_nexus       *nexus;
    struct ib_qp            *qp;
    union {
      struct {
        struct ib_cm_id         *cm_id;
      } ib_cm;
      struct {
        struct rdma_cm_id       *cm_id;
      } rdma_cm;
    };
    struct ib_cq            *cq;
    u32 cq_size;
    struct ib_cqe           zw_cqe;
    struct rcu_head         rcu;
    struct kref             kref;
    struct completion       *closed;
    int rq_size;
    u32 max_rsp_size;
    atomic_t sq_wr_avail;
    struct srpt_port        *sport;
    int max_ti_iu_len;
    atomic_t req_lim;
    atomic_t req_lim_delta;
    u16 imm_data_offset;
    spinlock_t spinlock;
    enum rdma_ch_state      state;
    struct kmem_cache       *rsp_buf_cache;
    struct srpt_send_ioctx  **ioctx_ring;
    struct kmem_cache       *req_buf_cache;
    struct srpt_recv_ioctx  **ioctx_recv_ring;
    struct list_head        list;
    struct list_head        cmd_wait_list;
    uint16_t pkey;
    bool using_rdma_cm;
    bool processing_wait_list;
    struct se_session       *sess;
    u8 sess_name[40];
    struct work_struct      release_work;
 };

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🌸 Members 🌸

okay this is the part where we meet every single field like they're members of the friend group 🫶

• nexus — the I_T nexus this channel is associated with. her plus-one, basically.
• qp — the IB queue pair used for communicating over this channel. the actual mouthpiece 💬
• {unnamed_union} — anonymous. she has no name and she doesn't need one 💅
• ib_cm — see below bestie 👇
• ib_cm.cm_id — the IB CM ID associated with the channel.
• rdma_cm — see below, again 👇
• rdma_cm.cm_id — the RDMA CM ID associated with the channel.
• cq — the IB completion queue for this channel.
• cq_size — the number of CQEs in cq. it's giving headcount 🔢
• zw_cqe — the zero-length write CQE. tiny but iconic.
• rcu — an RCU head.
• kref — the kref for this channel.
• closed — a completion object that will be signaled as soon as a new channel object with the same identity can be created. she tells you the moment the seat's free 🪑
• rq_size — the IB receive queue size.
• max_rsp_size — the maximum size of an RSP response message, in bytes.
• sq_wr_avail — the number of work requests available in the send queue.
• sport — a pointer to the information of the HCA port used by this channel.
• max_ti_iu_len — the maximum target-to-initiator information unit length.
• req_lim — the request limit: the maximum number of requests that may be sent by the initiator without having received a response. boundaries, bestie ✋
• req_lim_delta — the number of credits not yet sent back to the initiator.
• imm_data_offset — the offset from start of SRP_CMD for immediate data.
• spinlock — protects free_list and state. do not skip the lock, i'm begging 😭
• state — the channel state. see also enum rdma_ch_state.
• rsp_buf_cache — the kmem_cache for ioctx_ring.
• ioctx_ring — the send ring.
• req_buf_cache — the kmem_cache for ioctx_recv_ring.
• ioctx_recv_ring — the receive I/O context ring.
• list — the node in srpt_nexus.ch_list.
• cmd_wait_list — the list of SCSI commands that arrived before the RTU event. this list contains struct srpt_ioctx elements and is protected against concurrent modification by the cm_id spinlock. 🔒 very much protected, very much not to be touched by just anybody.
• pkey — the P_Key of the IB partition for this SRP channel.
• using_rdma_cm — whether the RDMA/CM or IB/CM is used for this channel. pick a lane, she said 💁‍♀️
• processing_wait_list — whether or not cmd_wait_list is being processed.
• sess — the session information associated with this SRP channel.
• sess_name — the session name.
• release_work — allows scheduling of srpt_release_channel.

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👑 SEE ALSO 👑

go read these next, i promise they eat 🔥

Kernel file ./drivers/infiniband/ulp/srpt/ib_srpt.h enum srpt_command_state(9), struct srpt_ioctx(9), struct srpt_recv_ioctx(9), struct srpt_send_ioctx(9), enum rdma_ch_state(9), struct srpt_nexus(9), struct srpt_port_attrib(9), struct srpt_tpg(9), struct srpt_port_id(9), struct srpt_port(9), struct srpt_device(9)

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and that's the page, bestie 🌈 mwah 💋 — brought to you by the fine folks at ./drivers/infiniband/ulp/srpt, dated October 2026, and titled struct srpt_rdma_ch(9) in case you forgot already 🙈 periodt ✨