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[34.48.33.21]) by smtp.gmail.com with UTF8SMTPSA id 00721157ae682-7952a085999sm70633397b3.25.2026.02.08.08.25.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Feb 2026 08:25:40 -0800 (PST) Date: Sun, 08 Feb 2026 11:25:40 -0500 From: Willem de Bruijn To: Vadim Fedorenko , Willem de Bruijn , Sebastian Andrzej Siewior , Willem de Bruijn , Jakub Kicinski , Paolo Abeni , Eric Dumazet , "David S. Miller" Cc: "Loktionov, Aleksandr" , Kurt Kanzenbach , "Nguyen, Anthony L" , "Kitszel, Przemyslaw" , Paul Menzel , "Gomes, Vinicius" , "netdev@vger.kernel.org" , Richard Cochran , "linux-kernel@vger.kernel.org" , Andrew Lunn , "intel-wired-lan@lists.osuosl.org" , "Keller, Jacob E" Message-ID: In-Reply-To: <601f0c4b-52d8-4b60-96bf-f2d65f8073d8@linux.dev> References: <20260205-igb_irq_ts-v3-1-2efc7bc4b885@linutronix.de> <20260205100347.ssTBDAI_@linutronix.de> <6a0f4cbb-e8b3-4f0e-b7f1-7f9ca5cba97d@linux.dev> <20260205145104.iWinkXHv@linutronix.de> <66925f09-ef9f-4401-baec-7d4c82a68ce3@linux.dev> <20260205164341.pJvni8kA@linutronix.de> <76acd5cc-eb6f-4c56-a5e6-f6413736afbb@linux.dev> <601f0c4b-52d8-4b60-96bf-f2d65f8073d8@linux.dev> Subject: Re: [Intel-wired-lan] [PATCH iwl-next v3] igb: Retrieve Tx timestamp directly from interrupt for i210 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Vadim Fedorenko wrote: > On 05.02.2026 21:41, Willem de Bruijn wrote: > > Vadim Fedorenko wrote: > >> On 05/02/2026 16:43, Sebastian Andrzej Siewior wrote: > >>> On 2026-02-05 16:27:03 [+0000], Vadim Fedorenko wrote: > >>>>> So the only thing that bothers me is the read_lock_bh() in > >>>>> skb_may_tx_timestamp() which deadlocks if the socket is write-loc= ked on > >>>>> the same CPU. > >>>> > >>>> Alright. Now you make me think whether we should enforce OPT_TSONL= Y > >>>> option on socket which doesn't have CAP_NET_RAW? Then we can get r= id of this > >>>> check, and in case sysctl was flipped off - drop TX timestamps as > >>>> it's done now? > >>> > >>> This would "fix" this problem for all users which do deliver the > >>> timestamp from their IRQ handler instead of napi. There are a few o= f > >>> those=E2=80=A6 > >>> This would be considered stable material, right? (despite the fact = that > >>> we have it for quite some time and nobody complained so far). > >> > >> cc: Willem as he is the author of the check introduced back in 2015.= > >> > >> But it's more like a question to maintainers whether it is acceptabl= e > >> way of "fixing" drivers or it's no-go solution > > = > > Requiring OPT_TSONLY unless CAP_NET_RAW would break legacy users. > = > Well, they are kinda broken already. Without OPT_TSONLY and CAP_NET_RAW= all TX > timestamps are silently dropped. Are you referring to sysctl_tstamp_allow_data? That is enabled by default. > To receive these timestamps users have to get > CAP_NET_RAW permission, and it will work with the updated logic as well= ...