On 08/03/2021 13:20, Matthew Wilcox wrote:
> On Mon, Mar 08, 2021 at 10:46:37AM +0000, Pavel Begunkov wrote:
>> Matthew, any chance you remember whether idr_for_each tolerates
>> idr_remove() from within the callback? Nothing else is happening in
>> parallel.
>
> No, that's not allowed. The design of the IDR is that you would free
> the thing being pointed to and then call idr_destroy() afterwards to
Gotcha, thanks!
> free the IDR's data structures. But this should use an XArray anyway.
> Compile-tested only.
Yeah, I remember this patch, looks good but 1 comments below.
Anyway, I'll rebase and resend it shortly for convenience.
[...]
> @@ -9532,14 +9531,16 @@ static int io_probe(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_args)
> static int io_register_personality(struct io_ring_ctx *ctx)
> {
> const struct cred *creds;
> + u32 id;
> int ret;
>
> creds = get_current_cred();
>
> - ret = idr_alloc_cyclic(&ctx->personality_idr, (void *) creds, 1,
> - USHRT_MAX, GFP_KERNEL);
> - if (ret < 0)
> - put_cred(creds);
> + ret = xa_alloc_cyclic(&ctx->personalities, &id, (void *)creds,
> + XA_LIMIT(0, USHRT_MAX), &ctx->pers_next, GFP_KERNEL);
ids are >=1, because 0 is kind of a reserved value for io_uring, so I guess
XA_LIMIT(1, USHRT_MAX)
> + if (!ret)
> + return id;
> + put_cred(creds);
> return ret;
> }
>
>
--
Pavel Begunkov
