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Tue, 12 May 2026 13:04:08 -0700 (PDT) Message-ID: Date: Tue, 12 May 2026 14:04:07 -0600 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/5] io_uring/epoll: disallow adding an epoll file to an epoll context To: Christian Brauner Cc: io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, Linus Torvalds References: <20260503085101.112698-1-axboe@kernel.dk> <20260503085101.112698-6-axboe@kernel.dk> <177861542131.846060.10743549776459529700.b4-review@b4> Content-Language: en-US From: Jens Axboe In-Reply-To: <177861542131.846060.10743549776459529700.b4-review@b4> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/12/26 1:50 PM, Christian Brauner wrote: > On Sun, 03 May 2026 02:49:16 -0600, Jens Axboe wrote: >> diff --git a/io_uring/epoll.c b/io_uring/epoll.c >> index 59cd4f009648..42057aab9124 100644 >> --- a/io_uring/epoll.c >> +++ b/io_uring/epoll.c >> @@ -62,6 +62,9 @@ int io_epoll_ctl(struct io_kiocb *req, unsigned int issue_flags) >> CLASS(fd, tf)(ie->fd); >> if (fd_empty(tf)) >> return -EBADF; >> + /* disallow adding an epoll context to another epoll context */ >> + if (ie->op == EPOLL_CTL_ADD && is_file_epoll(fd_file(tf))) >> + return -EINVAL; > > This is the same pattern in epoll itself. > Might be worth also adding a tiny helper for this that both codepaths > can reuse.\ My preference would be to just open-code it, then it's immediately obviously what it does. Unless you feel strongly about it? -- Jens Axboe