RDMA_DEREG_MR(3)

💖 RDMA_DEREG_MR 💖

okay bestie, so this one lives in section 3 of the Librdmacm Programmer's Manual — yeah, the rdma_dereg_mr page. it's the cleanup girlie of the RDMA world and honestly? she serves. 🧹✨

✨ NAME ✨

rdma_dereg_mr — deregisters a registered memory region.

like. she UN-registers it. the memory region gets its walking papers. 💅

🌸 SYNOPSIS 🌸

#include <rdma/rdma_verbs.h>

int rdma_dereg_mr (struct ibv_mr *mr);

🎀 ARGUMENTS 🎀

• mr — a reference to a registered memory buffer. that's it. that's the whole vibe. she just needs to know which buffer you're breaking up with. 💔

🦋 DESCRIPTION 🦋

so here's the tea: rdma_dereg_mr deregisters a memory buffer that had been registered for RDMA or message operations. basically, the buffer said yes to the registration, and now it's saying "we need to talk." 🫶

and like, bestie, this is not optional-optional. a user should call rdma_dereg_mr for all registered memory associated with an rdma_cm_id before destroying the rdma_cm_id. do not skip this step. do not pass go. do not leave your registered memory just hanging there. 😭

think of it as the "text them back before you block them" of RDMA. clean exits only. ✨

🔥 RETURN VALUE 🔥

• Returns 0 on success — slay, it worked, iconic, no notes. 👑
• Returns -1 on error — and if an error occurs, errno will be set to indicate the failure reason. so like, check errno, she's telling you exactly what went wrong. 🙈

💜 NOTES 💜

real talk: all memory registered with an rdma_cm_id is associated with the protection domain associated with the id. so they're linked. they're bonded. they're in a situationship that you created. 🌈

and users must deregister all registered memory before the protection domain can be destroyed. like, the protection domain will not go quietly until every last region has been deregistered. periodt. 💅

⚠️ okay so this is the part where people get messy — don't be the person who tries to destroy the protection domain with registered memory still clinging to it. deregister first. always. no cap.

⭐ SEE ALSO ⭐

• rdma_cm(7)
• rdma_create_id(3)
• rdma_create_ep(3)
• rdma_destroy_id(3)
• rdma_destroy_ep(3)
• rdma_reg_msgs(3)
• rdma_reg_read(3)
• rdma_reg_write(3)
• ibv_reg_mr(3)
• ibv_dereg_mr(3)

iykyk. go read them, bestie, they're all in the same friend group. 🍓

and that's the whole page!! this lil masterpiece came from librdmacm, dated 2010-07-19 — yeah she's been around since forever and she's still relevant, main character energy fr fr. mwah, take care of your memory regions 💖✨🎀