Re: [PATCH v2 net 1/5] pds_core: Prevent possible adminq overflow/stuck condition

[Simon Horman]

On Thu, Apr 10, 2025 at 05:32:05PM -0700, Shannon Nelson wrote:
> From: Brett Creeley <brett.creeley@xxxxxxx>
> 
> The pds_core's adminq is protected by the adminq_lock, which prevents
> more than 1 command to be posted onto it at any one time. This makes it
> so the client drivers cannot simultaneously post adminq commands.
> However, the completions happen in a different context, which means
> multiple adminq commands can be posted sequentially and all waiting
> on completion.
> 
> On the FW side, the backing adminq request queue is only 16 entries
> long and the retry mechanism and/or overflow/stuck prevention is
> lacking. This can cause the adminq to get stuck, so commands are no
> longer processed and completions are no longer sent by the FW.
> 
> As an initial fix, prevent more than 16 outstanding adminq commands so
> there's no way to cause the adminq from getting stuck. This works
> because the backing adminq request queue will never have more than 16
> pending adminq commands, so it will never overflow. This is done by
> reducing the adminq depth to 16.
> 
> Fixes: 45d76f492938 ("pds_core: set up device and adminq")
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@xxxxxxxxxxxxxxx>
> Signed-off-by: Brett Creeley <brett.creeley@xxxxxxx>
> Signed-off-by: Shannon Nelson <shannon.nelson@xxxxxxx>

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>