From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B3ED52E9ED4; Mon, 8 Sep 2025 13:30:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757338227; cv=none; b=i3RbV6oqENItaOQcwTIZyoHMBTxIn8gDx7uSUiYc/+Q/vy4Hi682SyrjmNF8Pz63qS/xzjERXwj2ZVow7Tj1Guadpyg+sxCxNrudN8FG8wi5qpFJlPdlyq8hdY4UwigKgUd75MUrtnshjmCCTe+vJ/ZEcDI7mzU5TCxMxrnvl4E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757338227; c=relaxed/simple; bh=CZTn/zUMVStp6lNcr/hrrgF5WR38lS/xc+w5UwVRfuQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=SGdi9bWuuTl/omon5v5Cy1caMR0ODDCIvYCuF7zwW772wsRNSs/hSzsF3fsHWQCAUzubMATPorfCX5VO+bMq+o3+t7osmPCf4kj78571Bcl/rr5gG/ozb0zwyvTpsw65lBDVUVgFv8N5Pg1bwfkAvhY0FgCVteg5z4S2OAeHzU8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=zM7OQuiq; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Dtz20LEL; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="zM7OQuiq"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Dtz20LEL" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1757338218; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=QDiE7+12FoK+K6JwIJkB7PeHaR+Gh06/ZX6DgEpac6w=; b=zM7OQuiqNxvMMTGw/6vBwwVNHKnbmv5P16z70f2WR6jeyO+BxReLS8Q6Q5FkSZQt2+44/y wTvcC0BiRhSz27hatHHqtOsMo3cLijAjDOBIZF2gQE3RWdZ3UWuMIo2ZaCkSRypyLX5p38 eNyj5uNcqopdQwXIkA0TnoheW+q5NlLPqGGd/g1EDCkQwO6Cpfnl1vreqDY6lqB1h386Xm GQAMkyVhC5vcqDABRd0Ulqgd6Na5p5ZlfVq//fPp7qpJ7b0GABL43bMpyItmO7gmYO8h7H D+N9GlATlpMCAiADwsmNiYBHKi93EUsM+hnsTlQ+RkV5o7v0HtVMBeVMM2ojxw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1757338218; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=QDiE7+12FoK+K6JwIJkB7PeHaR+Gh06/ZX6DgEpac6w=; b=Dtz20LELY1TpS5eB+tAKMoDZ95Z7fGNrV2eBJvSUJ8dB3p95jwZh6dxVqkgeqQGkZU8FyD tSzYyParAFAknIDw== To: Mike Galbraith , Breno Leitao , Simon Horman , kuba@kernel.org, calvin@wbinvd.org Cc: Pavel Begunkov , Johannes Berg , paulmck@kernel.org, LKML , netdev@vger.kernel.org, boqun.feng@gmail.com Subject: Re: netconsole: HARDIRQ-safe -> HARDIRQ-unsafe lock order warning In-Reply-To: <7fc8a1db60de959fd22ae898e86683f57fb07be2.camel@gmx.de> References: <3dd73125-7f9b-405c-b5cd-0ab172014d00@gmail.com> <4c4ed7b836828d966bc5bf6ef4d800389ba65e77.camel@gmx.de> <7a2b44c9e95673829f6660cc74caf0f1c2c0cffe.camel@gmx.de> <5b509b1370d42fd0cc109fc8914272be6dcfcd54.camel@gmx.de> <84a539f4kf.fsf@jogness.linutronix.de> <7fc8a1db60de959fd22ae898e86683f57fb07be2.camel@gmx.de> Date: Mon, 08 Sep 2025 15:36:17 +0206 Message-ID: <84frcx842e.fsf@jogness.linutronix.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On 2025-09-06, Mike Galbraith wrote: >> The ->write_atomic() callback is intended to perform immediate >> transmission. It is called with hardware interrupts disabled and is even >> expected to work from NMI context. If you are not able to implement >> these requirements, do not implement ->write_atomic(). Implementing some >> sort of deferrment mechanism is inappropriate. Such a mechanism already >> exists based on ->write_thread(). > > Truly atomic packet blasting would be a case of happiness, but barring > that, deferment is way better than the nothing that's available to both > RT and !RT+wireless here/now. With a .write_atomic that's really just > .write_thread, both RT and !RT+wireless managed to successfully send a > death rattle with the WIP nbcon patch.. a progression for each of them. Just be aware that ->write_atomic() will be called from _any_ context (including scheduler and NMI) and a console implementing this callback must handle the message or the message is lost for that console. I request that I am added CC to the next incarnation of this series. Thanks! John Ogness