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Date: Wed, 5 Jun 2024 19:54:20 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>, Andrew Lunn
 <andrew@lunn.ch>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, "David S. Miller"
 <davem@davemloft.net>, Daniel Bristot de Oliveira <bristot@kernel.org>,
 Boqun Feng <boqun.feng@gmail.com>, Daniel Borkmann <daniel@iogearbox.net>,
 Eric Dumazet <edumazet@google.com>, Frederic Weisbecker
 <frederic@kernel.org>, Ingo Molnar <mingo@redhat.com>, Paolo Abeni
 <pabeni@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner
 <tglx@linutronix.de>, Waiman Long <longman@redhat.com>, Will Deacon
 <will@kernel.org>
Subject: Re: [PATCH v4 net-next 03/14] net: Use nested-BH locking for
 napi_alloc_cache.
Message-ID: <20240605195420.2f47e6a1@kernel.org>
In-Reply-To: <20240604154425.878636-4-bigeasy@linutronix.de>
References: <20240604154425.878636-1-bigeasy@linutronix.de>
	<20240604154425.878636-4-bigeasy@linutronix.de>
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On Tue,  4 Jun 2024 17:24:10 +0200 Sebastian Andrzej Siewior wrote:
> @@ -308,6 +311,7 @@ void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
>  	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
>  
>  	fragsz = SKB_DATA_ALIGN(fragsz);
> +	guard(local_lock_nested_bh)(&napi_alloc_cache.bh_lock);
>  
>  	return __page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC,
>  				       align_mask);

We have decided to advise against the use of guard() in networking, 
at least for now.

Andrew, wasn't it on your TODO list to send the update to the docs? :)