dma_buf_put(9)

📦 version 7.3.1, in nixpkgs unstable

💅 dma_buf_put — a Kernel API Manual moment (yes, that's the 9 section, iykyk)

okay so bestie, welcome to the group chat. this page lives in the Kernel API Manual and it's literally about letting go of a buffer. one function, huge main character energy. let's get into it 💖

🌸 NAME 🌸

dma_buf_put — decreases refcount of the buffer

like, it's the "okay bye ily but I'm leaving" of reference counting. no cap.

✨ SYNOPSIS ✨

void dma_buf_put (struct dma_buf *dmabuf );

that's it. that's the whole signature. she's simple, she's iconic, she returns nothing (void) and she's not sorry about it. 🎀

🫶 ARGUMENTS 🫶

  • dmabuf — [in] the buffer to reduce refcount of. that's your little guy. you're lowering his refcount. be gentle. 🦋

💅 DESCRIPTION 💅

so here's the tea: this function uses the file's refcounting, and that refcounting is done implicitly by fput. no extra work from you, it just vibes through the file layer. ✨

now the dramatic part — if, as a result of this call, the refcount becomes 0, then the 'release' file operation related to this fd gets called. and that in turn calls the dma_buf_ops.release vfunc, and frees the memory allocated for dmabuf when it was exported. so it's giving final rose ceremony. when the count hits zero, the memory gets its goodbye moment. 😭👑

ngl this is the important bit: the cleanup doesn't happen at some random time. it happens on this call, the one that drops the count to 0. so like, mind your refcounts bestie. 💀

🔥 SEE ALSO 🔥

that's the whole friend group. the dma_buf_get / dma_buf_put duo is literally the classic paired set — grab one, put one back. iykyk 💜

and that's the page bestie! 🌈 this one comes to you from ./drivers/dma-buf, dated October 2026, and the page itself is dma_buf_put(9). go forth and decrement responsibly. mwah 🍓🧚💖

📦 where this page comes from