drm_event_reserve_init(9)

💫 drm_event_reserve_init(9) 💫

okay bestie, so this one lives in the Kernel API Manual and it's literally the "get your event ready and grab the space for it" function. no cap. 🎀

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✨ SYNOPSIS ✨

int drm_event_reserve_init (struct drm_device *dev , struct drm_file
*file_priv , struct drm_pending_event *p , struct drm_event *e );

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🌸 ARGUMENTS 🌸

• dev — the DRM device, your main character 🫶
• file_priv — DRM file private data, iykyk
• p — the tracking structure for the pending event (yes, the whole point)
• e — the actual event data you're gonna deliver to userspace 💌

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🦋 DESCRIPTION 🦋

So this function's whole job is prepping the event you passed in for eventual delivery. it's giving "make it ready for its moment."

But — and this is the important part, so listen up — if the event doesn't get delivered (like, the IOCTL fails later on, before anything gets queued up), then you must cancel and free it using drm_event_cancel_free. no leaving it hanging, that's so not slay. 😭

Once events are successfully initialized, you send them out with drm_send_event or drm_send_event_locked to signal that the asynchronous event has completed. periodt. 💅

⭐ Little structural rule for you: if callers embedded p into a larger structure, it must be allocated with kmalloc, and p must be the first member element. that's the vibe check, don't fight it.

And if you're already holding drm_device.event_lock? then you should use drm_event_reserve_init_locked instead. no double-locking drama please. 🙈

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🔥 RETURN 🔥

0 on success, or a negative error code if it failed. that's it, that's the whole report. 🍓

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👑 SEE ALSO 👑

Kernel file ./drivers/gpu/drm/drm_file.c file operations(9), drm_file_alloc(9), drm_file_free(9), drm_open(9), drm_release(9), drm_release_noglobal(9), drm_read(9), drm_poll(9), drm_event_reserve_init_locked(9), drm_event_cancel_free(9), drm_send_event_timestamp_locked(9), drm_send_event_locked(9), drm_send_event(9), drm_print_memory_stats(9), drm_show_memory_stats(9), drm_show_fdinfo(9), drm_file_err(9), mock_drm_getfile(9) — go read them, they're all icons ✨

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💖 that's the whole page bestie, go forth and reserve your events 💖

this masterpiece came from ./drivers/gpu/drm, dated October 2026. mwah, love u, bye 🧚💜