Jens Axboe <axboe@xxxxxxxxx> writes:
> On 3/13/24 4:32 PM, Gabriel Krisman Bertazi wrote:
>> Pavel Begunkov <asml.silence@xxxxxxxxx> writes:
>>
>>> io_mem_alloc() returns a pointer on success and a pointer-encoded error
>>> otherwise. However, it can only fail with -ENOMEM, just return NULL on
>>> failure. PTR_ERR is usually pretty error prone.
>>>
>>> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
>>> ---
>>> io_uring/io_uring.c | 14 +++++---------
>>> io_uring/kbuf.c | 4 ++--
>>> 2 files changed, 7 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
>>> index e7d7a456b489..1d0eac0cc8aa 100644
>>> --- a/io_uring/io_uring.c
>>> +++ b/io_uring/io_uring.c
>>> @@ -2802,12 +2802,8 @@ static void io_rings_free(struct io_ring_ctx *ctx)
>>> void *io_mem_alloc(size_t size)
>>> {
>>> gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
>>> - void *ret;
>>>
>>> - ret = (void *) __get_free_pages(gfp, get_order(size));
>>> - if (ret)
>>> - return ret;
>>> - return ERR_PTR(-ENOMEM);
>>> + return (void *) __get_free_pages(gfp, get_order(size));
>>> }
>>>
>>> static unsigned long rings_size(struct io_ring_ctx *ctx, unsigned int sq_entries,
>>> @@ -3762,8 +3758,8 @@ static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
>>> else
>>> rings = io_rings_map(ctx, p->cq_off.user_addr, size);
>>>
>>> - if (IS_ERR(rings))
>>> - return PTR_ERR(rings);
>>> + if (!rings)
>>> + return -ENOMEM;
>>>
>>
>> Sorry, I started reviewing this, got excited about the error path quick
>> fix, and didn't finish the review before it got it.
>>
>> I think this change is broken for the ctx->flags & IORING_SETUP_NO_MMAP
>> case, because io_rings_map returns ERR_PTR, and not NULL. In addition,
>> io_rings_map might fail for multiple reasons, and we want to propagate
>> the different error codes up here.
>
> Yeah, see my reply from some hours ago. I dropped it back then.
ah, thanks. I've configured lei to fetch the io_uring list every few
hours. This ended up fetching part of the thread at first, and I only saw
it dropped in the next fetch, after I sent the email. sorry for the noise.
--
Gabriel Krisman Bertazi
