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([2001:a61:133d:ff01:f29d:4e4:f043:caa2]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b07d2870da1sm1004985666b.13.2025.09.17.03.10.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 17 Sep 2025 03:10:50 -0700 (PDT) Message-ID: <0f2fe17b-89bb-4464-890d-0b73ed1cf117@suse.com> Date: Wed, 17 Sep 2025 12:10:48 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v1 1/1] net: usb: asix: forbid runtime PM to avoid PM/MDIO + RTNL deadlock To: Oleksij Rempel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: =?UTF-8?Q?Hubert_Wi=C5=9Bniewski?= , Marek Szyprowski , stable@vger.kernel.org, kernel@pengutronix.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Lukas Wunner , Russell King , Xu Yang , linux-usb@vger.kernel.org References: <20250917095457.2103318-1-o.rempel@pengutronix.de> Content-Language: en-US From: Oliver Neukum In-Reply-To: <20250917095457.2103318-1-o.rempel@pengutronix.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 17.09.25 11:54, Oleksij Rempel wrote: > With autosuspend active, resume paths may require calling phylink/phylib > (caller must hold RTNL) and doing MDIO I/O. Taking RTNL from a USB PM > resume can deadlock (RTNL may already be held), and MDIO can attempt a > runtime-wake while the USB PM lock is held. Given the lack of benefit > and poor test coverage (autosuspend is usually disabled by default in > distros), forbid runtime PM here to avoid these hazards. This reasoning depends on netif_running() returning false during system resume. Is that guaranteed? Regards Oliver