From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793790123; b=KDHsv5U3Rtjka4vVYSOszPNWjcaIXHbLn+x3HCu1a2IQU8a6J19Mvi5AJ+XZ0aKQQxz0 16EzW+d06LF6yb1hqWsH7Uo6pglSsoLg4AQp2nSpB7Y9+r4nX5kKIYeDfg5JCjHsEzh0+ Q6d0Ujl3mmFxx0nOEI5N+anhYHmc09OMDgcZzb6j0jWHJVxgFgtQUbyWhCG0PcFEpX357 KLNh19MznBZ3kxBYAKS0zMfYcYLcW6ICAPijufdp/3gfbj7QcYpf85NWhOODBhZn/oDIe b8g4v7R3/8yXskDhI2O9XB1nQhmIopYJBgZJlYD+N0/GDzwQbNlyTeGLXcm71ogEeUw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793790123; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=Y8jmoenn5x6HnOWI433fGlVPwdvHn98UjlBn+9E6RNQ=; b=Z/PVcWO8lSRmbBqh2sul/ch5xTrM2wXVIE4R2SVwoa2fhNWkxqhCIZg1gXJBmsPQ8RFM poVIoGrymrZFuPzyBP2EvKOldj+b4tNlpUF0IECySZ7P7/IShEwjQUa4EB3s71/Psmwog RjC9/UMaVVeDHsmKqDnMH5hdRINoRKxnuZgJWIJu93LqFDUzvzgM4M1lZfpVSg5lTw2eq 7soQ2DIR8Ghh6RTnCdRcv+n6Y+U5E8yd73qMZeM1GHVOsd8nTlkAdjgbBm00WQjTjMrHD dDg0q6XVWSkc5qWgs6psMPBxgZp+sW2Jxn1UWXSDJU57qz/+7Ktl5gPpRTiqwQ/ywBQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="bBVZ5Xp/"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BA0D3606A31B for ; Wed, 4 Nov 2026 11:02:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=bBVZ5Xp/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38DCC1F000C1; Wed, 4 Nov 2026 11:02:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793790122; bh=Y8jmoenn5x6HnOWI433fGlVPwdvHn98UjlBn+9E6RNQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=bBVZ5Xp/u1nJDGEROb4Su82vLzkXxMgOrAt78xCDVs2KQns87dlN8oRfw+ymrj90J B5+BE3mfjvfvOGvOgpwYaX89nmTBtIzkbsAGGmCocfjGFSvj5ag2er4xkA22X4bQz3 u84uBBBs+hv46IFCQspellDUVe90tXqflrLOr9MSbr1n7847ccZeZXNovtrOlaShHk oehrhGx6xSq1yo98KKMVHPw0Qbi7UijRkKBb994/8v+XxbFz+RXgJOOYSfNLwNVtRe oL6RxVZC38IXwnVsk7seKhjOzSIoqqUnHLTOgflXGYnjtqlnH+JH+M3J9zIUThs/Nz wZdsWkfSum1yA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH] serial: amba-pl011: touch the watchdogs in write_atomic() Reply-To: sashiko-reviews@lists.linux.dev To: "Breno Leitao" Cc: linux-serial@vger.kernel.org In-Reply-To: <20261104-pl011_touch-v1-1-e292bd834e14@debian.org> References: <20261104-pl011_touch-v1-1-e292bd834e14@debian.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 04 Nov 2026 11:02:01 +0000 X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > In emergency context, such as WARN(), nbcon prints the pending records > through write_atomic() with preemption disabled. >=20 > On arm64, WARN() can run with IRQs masked, so the whole backlog is > printed with IRQs off as well. >=20 > Commit 9bd18e1262c0 ("printk/nbcon: Restore IRQ in atomic flush after > each emitted record") does not help here, as it only restores the > caller's IRQ state between records. >=20 > pl011_console_write_atomic() busy-waits on the UART for every > character, and at 115200 baud it prints about 11.5KB per second. > Flushing a few hundred kilobytes outlasts the hard lockup threshold > (10 seconds by default), so the printing CPU is reported, or the > machine panics with hardlockup_panic set. See [1]. >=20 > The 8250 driver avoids this by calling touch_nmi_watchdog() while it > polls the transmitter. Do the same in pl011_console_write_atomic(), > once per record. >=20 > Suggested-by: John Ogness > Link: https://lore.kernel.org/all/87wlqtxb14.fsf@jogness.linutronix.de/ [= 1] > Signed-off-by: Breno Leitao Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261104-pl011_touc= h-v1-1-e292bd834e14@debian.org?part=3D1