From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3BB31E7719A for ; Sat, 11 Jan 2025 08:12:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: Message-ID:Date:References:In-Reply-To:Subject:Cc:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=IeQj/164SGrmH9lzgL8p5lsNgKqMm7GxQlCG6lh3BS4=; b=eWXBvM5be/cGDQEdXe94xXcnoc L8avgOJd0LF0nEqDboaIpn7XLslhEcXXAw0zLmphYKAOMYOBWRabV7LkMcf7aLKkGmJoZbv3P9A4Q OYv9LwYZuduo4RIzV8rAqjwXCKMXcBsJZrZkggocrorWcDzwjXHmBoAPKOSWPSuamBCK5chSWb2T4 TNZOKKW5PazT9AxcwWx09GeE/cOtJXGD3gTw0DbhnArHrwuEaaiBo45CaqjMVuMHN20SvaCwZF0zj TMVQMKSglzuhDV/8zs2ZqVKBgWNTmj8kgS0W5T/EYYKJs1TAUlXTimmb0kLTUKFy2QrQsletXaFF6 FETI2ohg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tWWbL-00000000Pd9-0kJx; Sat, 11 Jan 2025 08:12:11 +0000 Received: from galois.linutronix.de ([2a0a:51c0:0:12e:550::1]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tWWa6-00000000PY2-1oA0 for linux-arm-kernel@lists.infradead.org; Sat, 11 Jan 2025 08:10:55 +0000 From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1736583049; 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=IeQj/164SGrmH9lzgL8p5lsNgKqMm7GxQlCG6lh3BS4=; b=n/VjPBu6RVxY/jd7/8ahukh+XhN8jl0TOU60fQm0lvgPHNpL5UGHyPLCU4qiDpVuz/P/fM Baq+YHYooJezQqzqekMCLlKMDROe+sbMilyNnTxxRQaZT1GlIgmmFOssoQKMCxCgPeHpdu C2TRtQU+y06mrOz5qDqZFIakhhG8EK6oniyYfefyQ0Qj6ibsdOBPmw0o736XKaWL83RMUG MMwg4rR7lsDvJ6EI0tIRjarpIGlnEZct3TDYkfCnEKtNiJxJu0ae1kOpHaD5Bwb/ZlRo4x zX5UlKMToWVyF+B/iGJphUlhJm6CItkUEGU2CD4aRwBKTLDFYZYOU2fBcpdItA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1736583049; 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=IeQj/164SGrmH9lzgL8p5lsNgKqMm7GxQlCG6lh3BS4=; b=U0RLWQenj5Pis/8c/yvegsbHfJFijpGnoXgqcP3V+STKLFb6zDGjAw6m+UkuSPoY2qE5Qj /wyWXytrTVwfqOBA== To: Sean Anderson , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org Cc: Manikanta Guntupalli , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Michal Simek , Thomas Gleixner , Sean Anderson , stable@vger.kernel.org Subject: Re: [PATCH] tty: xilinx_uartps: split sysrq handling In-Reply-To: <20250110213822.2107462-1-sean.anderson@linux.dev> References: <20250110213822.2107462-1-sean.anderson@linux.dev> Date: Sat, 11 Jan 2025 09:16:49 +0106 Message-ID: <841px9u5x2.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250111_001054_611581_F4B4E9AB X-CRM114-Status: UNSURE ( 7.06 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2025-01-10, Sean Anderson wrote: > Fix this by splitting sysrq handling into two parts. We use the prepare > helper under the port lock and defer handling until we release the lock. Note that this fix is only necessary because this console driver is using the legacy console API. For the NBCON API it is allowed to call printk() while holding the port lock. But since code already exists to allow deferring the sysrq execution until the port lock is not held, this patch is probably a good idea anyway because it can reduce port lock contention. AFAIK there are no sysrq actions that require port lock synchronization. Acked-by: John Ogness