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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Tantilov, Emil S" <emil.s.tantilov@intel.com>
Cc: intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
	anthony.l.nguyen@intel.com, aleksandr.loktionov@intel.com,
	przemyslaw.kitszel@intel.com, andrew+netdev@lunn.ch,
	davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
	pabeni@redhat.com, clrkwllms@kernel.org, rostedt@goodmis.org,
	linux-rt-devel@lists.linux.dev, sgzhang@google.com,
	boolli@google.com
Subject: Re: [PATCH iwl-net 0/3] idpf: virtchnl locking and async fixes
Message-ID: <20260317143850.BLrnAox8@linutronix.de>
References: <20260316232819.6872-1-emil.s.tantilov@intel.com>
 <20260317090054.DuPZ6O0O@linutronix.de>
 <7247024b-fc8d-4a75-ba15-a10399db03bc@intel.com>
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In-Reply-To: <7247024b-fc8d-4a75-ba15-a10399db03bc@intel.com>

On 2026-03-17 07:20:18 [-0700], Tantilov, Emil S wrote:
> > Why is there a raw_spinlock_t? From a quick look a spinlock_t would do
> > just fine with not runtime change for !PREEMPT_RT.
> 
> The handling of the virtchannel messages is done via the completion API
> and the transactions are using the raw spinlock from struct
> swait_queue_head:
> 
> https://elixir.bootlin.com/linux/v6.19.8/source/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c#L298
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/tnguy/net-queue.git/tree/include/linux/swait.h?h=dev-queue#n44

I am aware that completions use a raw_spinlock_t. I don't see the link.
What would break if you make that lock a spinlock_t?

> Thanks,
> Emil

Sebastian