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eventpoll: refresh epi_fget() / ep_remove_file() comments

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Two comments drifted from the code they sit on.

epi_fget()'s block comment still referenced atomic_long_inc_not_zero,
which has been file_ref_get() for a while, and described only one of
the function's two roles: safe dereference of epi->ffd.file under
ep->mtx. Since commit a6dc643c69 ("eventpoll: fix ep_remove struct
eventpoll / struct file UAF") the refcount bump also serves as a pin
that blocks __fput() from starting, which is what lets ep_remove()
touch file->f_lock and file->f_ep without racing
eventpoll_release_file(). Update the block to name both roles and the
commit that introduced the pin role.

ep_remove_file()'s one-line "See eventpoll_release() for details"
pointed at an inline in include/linux/eventpoll.h but said nothing
about what those details were. Replace it with a short explanation:
we publish NULL so the eventpoll_release() fastpath can skip the slow
path, and this is safe because every f_ep writer either holds a pin
via epi_fget() or is __fput() itself.

Comment-only; no functional change.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Link: https://patch.msgid.link/20260424-work-epoll-rework-v1-4-249ed00a20f3@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2026-04-24 15:46:35 +02:00
commit a573cb40f9
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1 changed files with 22 additions and 15 deletions
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