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Date: Mon, 29 Apr 2024 13:57:42 +0100
From: Simon Horman <horms@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: intel-wired-lan@lists.osuosl.org,
	Michal Kubiak <michal.kubiak@intel.com>,
	Wojciech Drewek <wojciech.drewek@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	nex.sw.ncis.osdt.itp.upstreaming@intel.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH iwl] idpf: don't enable NAPI and interrupts prior to
 allocating Rx buffers
Message-ID: <20240429125742.GX516117@kernel.org>
References: <20240426144408.1353962-1-aleksander.lobakin@intel.com>
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In-Reply-To: <20240426144408.1353962-1-aleksander.lobakin@intel.com>

On Fri, Apr 26, 2024 at 04:44:08PM +0200, Alexander Lobakin wrote:
> Currently, idpf enables NAPI and interrupts prior to allocating Rx
> buffers.
> This may lead to frame loss (there are no buffers to place incoming
> frames) and even crashes on quick ifup-ifdown. Interrupts must be
> enabled only after all the resources are here and available.
> Split interrupt init into two phases: initialization and enabling,
> and perform the second only after the queues are fully initialized.
> Note that we can't just move interrupt initialization down the init
> process, as the queues must have correct a ::q_vector pointer set
> and NAPI already added in order to allocate buffers correctly.
> Also, during the deinit process, disable HW interrupts first and
> only then disable NAPI. Otherwise, there can be a HW event leading
> to napi_schedule(), but the NAPI will already be unavailable.
> 
> Fixes: d4d558718266 ("idpf: initialize interrupts and enable vport")
> Reported-by: Michal Kubiak <michal.kubiak@intel.com>
> Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
> Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>

Reviewed-by: Simon Horman <horms@kernel.org>