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Date: Tue, 4 Nov 2025 15:48:28 -0800
From: Jakub Kicinski <kuba@kernel.org>
To: Meghana Malladi <m-malladi@ti.com>
Cc: Paolo Abeni <pabeni@redhat.com>, <horms@kernel.org>,
 <namcao@linutronix.de>, <vadim.fedorenko@linux.dev>,
 <jacob.e.keller@intel.com>, <christian.koenig@amd.com>,
 <sumit.semwal@linaro.org>, <sdf@fomichev.me>, <john.fastabend@gmail.com>,
 <hawk@kernel.org>, <daniel@iogearbox.net>, <ast@kernel.org>,
 <edumazet@google.com>, <davem@davemloft.net>, <andrew+netdev@lunn.ch>,
 <linaro-mm-sig@lists.linaro.org>, <dri-devel@lists.freedesktop.org>,
 <linux-media@vger.kernel.org>, <bpf@vger.kernel.org>,
 <linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
 <linux-arm-kernel@lists.infradead.org>, <srk@ti.com>, Vignesh Raghavendra
 <vigneshr@ti.com>, Roger Quadros <rogerq@kernel.org>, <danishanwar@ti.com>
Subject: Re: [EXTERNAL] Re: [PATCH net-next v4 2/6] net: ti: icssg-prueth:
 Add XSK pool helpers
Message-ID: <20251104154828.7aa20642@kernel.org>
In-Reply-To: <c792f4da-3385-4c14-a625-e31b09675c32@ti.com>
References: <20251023093927.1878411-1-m-malladi@ti.com>
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	<05efdc9a-8704-476e-8179-1a9fc0ada749@redhat.com>
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On Tue, 4 Nov 2025 14:23:24 +0530 Meghana Malladi wrote:
> > I tried honoring Jakub's comment to avoid freeing the rx memory wherever 
> > necessary.
> > 
> > "In case of icssg driver, freeing the rx memory is necessary as the
> > rx descriptor memory is owned by the cppi dma controller and can be
> > mapped to a single memory model (pages/xdp buffers) at a given time.
> > In order to remap it, the memory needs to be freed and reallocated."
> 
> Just to make sure we are on the same page, does the above explanation 
> make sense to you or do you want me to make any changes in this series 
> for v5 ?

No. Based on your reply below you seem to understand what is being
asked, so you're expected to do it.

> >> I think you should:
> >> - stop the H/W from processing incoming packets,
> >> - spool all the pending packets
> >> - attach/detach the xsk_pool
> >> - refill the ring
> >> - re-enable the H/W
> > 
> > Current implementation follows the same sequence:
> > 1. Does a channel teardown -> stop incoming traffic
> > 2. free the rx descriptors from free queue and completion queue -> spool 
> > all pending packets/descriptors
> > 3. attach/detach the xsk pool
> > 4. allocate rx descriptors and fill the freeq after mapping them to the 
> > correct memory buffers -> refill the ring
> > 5. restart the NAPI - re-enable the H/W to recv the traffic
> > 
> > I am still working on skipping 2 and 4 steps but this will be a long 
> > shot. Need to make sure all corner cases are getting covered. If this 
> > approach looks doable without causing any regressions I might post it as 
> > a followup patch later in the future.