From: Pavel Begunkov <[email protected]>
To: Markus Elfring <[email protected]>,
[email protected], [email protected],
Gabriel Krisman Bertazi <[email protected]>,
Jens Axboe <[email protected]>
Cc: LKML <[email protected]>
Subject: Re: [PATCH v2 2/2] io_uring: Improve exception handling in io_ring_ctx_alloc()
Date: Thu, 11 Jan 2024 13:23:31 +0000 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 1/10/24 20:50, Markus Elfring wrote:
> From: Markus Elfring <[email protected]>
> Date: Wed, 10 Jan 2024 21:15:48 +0100
>
> The label “err” was used to jump to a kfree() call despite of
> the detail in the implementation of the function “io_ring_ctx_alloc”
> that it was determined already that a corresponding variable contained
> a null pointer because of a failed memory allocation.
It's _much_ simpler the way it currently is, compare it with maintaining
a bunch of labels. That is the advantage of being able to distinguish
un-allocated state like NULL, just kfree them and don't care about
jumping to a wrong one or keeping them in order.
> 1. Thus use more appropriate labels instead.
>
> 2. Reorder jump targets at the end.
>
> Signed-off-by: Markus Elfring <[email protected]>
> ---
>
> See also:
> https://wiki.sei.cmu.edu/confluence/display/c/MEM12-C.+Consider+using+a+goto+chain+when+leaving+a+function+on+error+when+using+and+releasing+resources
>
>
> io_uring/io_uring.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index c9a63c39cdd0..7727cdd505ae 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -295,12 +295,14 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
> hash_bits = ilog2(p->cq_entries) - 5;
> hash_bits = clamp(hash_bits, 1, 8);
> if (io_alloc_hash_table(&ctx->cancel_table, hash_bits))
> - goto err;
> + goto destroy_io_bl_xa;
> +
> if (io_alloc_hash_table(&ctx->cancel_table_locked, hash_bits))
> - goto err;
> + goto free_cancel_table_hbs;
> +
> if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
> 0, GFP_KERNEL))
> - goto err;
> + goto free_cancel_table_locked_hbs;
>
> ctx->flags = p->flags;
> init_waitqueue_head(&ctx->sqo_sq_wait);
> @@ -341,9 +343,12 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
> INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
> INIT_HLIST_HEAD(&ctx->cancelable_uring_cmd);
> return ctx;
> -err:
> - kfree(ctx->cancel_table.hbs);
> +
> +free_cancel_table_locked_hbs:
> kfree(ctx->cancel_table_locked.hbs);
> +free_cancel_table_hbs:
> + kfree(ctx->cancel_table.hbs);
> +destroy_io_bl_xa:
> xa_destroy(&ctx->io_bl_xa);
> kfree(ctx);
> return NULL;
> --
> 2.43.0
>
--
Pavel Begunkov
next prev parent reply other threads:[~2024-01-11 13:33 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <[email protected]>
[not found] ` <[email protected]>
2024-01-10 11:23 ` io_uring: Fix exception handling in io_ring_ctx_alloc() Markus Elfring
2024-01-10 16:55 ` [cocci] [PATCH] " Gabriel Krisman Bertazi
2024-01-10 20:45 ` [PATCH v2 0/2] io_uring: Adjustments for io_ring_ctx_alloc() Markus Elfring
2024-01-10 20:48 ` [PATCH v2 1/2] io_uring: Delete a redundant kfree() call in io_ring_ctx_alloc() Markus Elfring
2024-01-12 14:25 ` Gabriel Krisman Bertazi
2024-01-12 16:18 ` Jens Axboe
2024-01-12 17:15 ` Gabriel Krisman Bertazi
2024-01-12 17:50 ` [v2 " Markus Elfring
2024-01-10 20:50 ` [PATCH v2 2/2] io_uring: Improve exception handling " Markus Elfring
2024-01-11 13:23 ` Pavel Begunkov [this message]
2024-01-12 14:30 ` Gabriel Krisman Bertazi
2024-01-12 15:00 ` [v2 " Markus Elfring
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