Re: [PATCH] io_uring/uring_cmd: add missing READ_ONCE() on shared memory read

[Jens Axboe]

On 1/22/25 12:38 PM, Jens Axboe wrote:
> 
> On Tue, 21 Jan 2025 17:09:59 +0100, Jann Horn wrote:
>> cmd->sqe seems to point to shared memory here; so values should only be
>> read from it with READ_ONCE(). To ensure that the compiler won't generate
>> code that assumes the value in memory will stay constant, add a
>> READ_ONCE().
>> The callees io_uring_cmd_getsockopt() and io_uring_cmd_setsockopt() already
>> do this correctly.
>>
>> [...]
> 
> Applied, thanks!
> 
> [1/1] io_uring/uring_cmd: add missing READ_ONCE() on shared memory read
>       commit: 0963dba3dc006b454c54fd019bbbdb931e7a7c70

I took a closer look and this isn't necessary. Either ->sqe is a full
copy at this point. Should probably be renamed as such... If we want to
make this clearer, then we should do:

-       switch (cmd->sqe->cmd_op) {
+       switch (cmd->cmd_op) {

instead.

I'll drop this one.

-- 
Jens Axboe