Re: [PATCH v3 1/6] event/dpaa2: disable channel before closing it

[Hemant Agrawal <hemant.agrawal@oss.nxp.com>]

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On 30-06-2026 20:13, Maxime Leroy wrote:
> rte_dpaa2_close_dpcon_device() called dpcon_close() but not
> dpcon_disable(). close only releases the MC control session; it does not
> disable the channel. Cosmetic: an idle DPCON generates nothing and every
> consumer reprograms on setup, so disable before close only to return the
> channel clean, as the symmetric counterpart of the dpcon_enable() done on
> setup.
>
> Signed-off-by: Maxime Leroy<maxime@leroys.fr>
> ---
>   drivers/event/dpaa2/dpaa2_hw_dpcon.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/event/dpaa2/dpaa2_hw_dpcon.c b/drivers/event/dpaa2/dpaa2_hw_dpcon.c
> index ea5b0d4b85..f65a63a786 100644
> --- a/drivers/event/dpaa2/dpaa2_hw_dpcon.c
> +++ b/drivers/event/dpaa2/dpaa2_hw_dpcon.c
> @@ -128,6 +128,7 @@ rte_dpaa2_close_dpcon_device(int object_id)
>   
>   	if (dpcon_dev) {
>   		rte_dpaa2_free_dpcon_dev(dpcon_dev);
> +		dpcon_disable(&dpcon_dev->dpcon, CMD_PRI_LOW, dpcon_dev->token);
>   		dpcon_close(&dpcon_dev->dpcon, CMD_PRI_LOW, dpcon_dev->token);
>   		TAILQ_REMOVE(&dpcon_dev_list, dpcon_dev, next);
>   		rte_free(dpcon_dev);

The ordering here is wrong. |rte_dpaa2_free_dpcon_dev(dpcon_dev)| is 
called *before* |dpcon_disable()|. Once the device is returned to the 
shared pool via |rte_dpaa2_free_dpcon_dev()|, another thread can 
immediately re-allocate the same |dpcon_dev| pointer. The subsequent 
|dpcon_disable()| call would then quiesce a channel already in active 
use by the new owner — a use-after-free on the pool object.

The correct teardown sequence must be:

 1. dpcon_disable() — quiesce the hardware channel
 2. dpcon_close() — release the MC control session
 3. rte_dpaa2_free_dpcon_dev() — return to pool

Please reorder accordingly:

dpcon_disable(&dpcon_dev->dpcon, CMD_PRI_LOW, dpcon_dev->token);

dpcon_close(&dpcon_dev->dpcon, CMD_PRI_LOW, dpcon_dev->token);

  TAILQ_REMOVE(&dpcon_dev_list, dpcon_dev, next);

  rte_dpaa2_free_dpcon_dev(dpcon_dev);

  rte_free(dpcon_dev);



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