From patchwork Thu Nov 12 20:47:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sven Van Asbroeck X-Patchwork-Id: 1399331 Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=N242L88X; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CXDFK6n3Nz9sSn for ; Fri, 13 Nov 2020 07:47:49 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727159AbgKLUrq (ORCPT ); Thu, 12 Nov 2020 15:47:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33276 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726621AbgKLUrq (ORCPT ); Thu, 12 Nov 2020 15:47:46 -0500 Received: from mail-qk1-x741.google.com (mail-qk1-x741.google.com [IPv6:2607:f8b0:4864:20::741]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22B00C0613D1; Thu, 12 Nov 2020 12:47:46 -0800 (PST) Received: by mail-qk1-x741.google.com with SMTP id v143so6809682qkb.2; Thu, 12 Nov 2020 12:47:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=36FLese2veI3iWY1QIV+jskXlXxefI3GQpE+1eH4p2M=; b=N242L88XsM3GRxlJ2PrswON7oLbOaXDRPkFkUypxgYjX70C2zM4TZ4z24sFdgzA5wO AGb9xNXSszor6MsYuSNJDjb5UZbLxVDyNYmvpqHyIXF8jkwegXAW+Chhn/nyIxtCb3oU H+EXURpITkmZlqTUEBwnNrgANQE1shcem8X9KTHmNIJEBmSlW/zYHzq8xl44thxor6IU sb/C91xxIwysSeTGnith13BHsiyF2THFRKtg4pn1R3shTmpX0kY4V6xuM6EhN9dX0UeO oRUNk7rR4kBHi4VudSvjH1yRt3n/E8rGLJWguEH0kEdXoB/VEQmS98RdPH8/mgbPKfcX M+7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=36FLese2veI3iWY1QIV+jskXlXxefI3GQpE+1eH4p2M=; b=Mq3h1bDmwyfPuCzMGIPLjuFRgY98qTmVF9fTjO9wAM4ziwUzizNsW/dPRXh2tNT680 5mc/zDmFbsQfDXJ2c+u9D2T1QJ9mCdk+Jh58uOBpotPy8/Ht3hhfJd7NFEbFjgHd+nRJ zGQeNez+Mfvht1xDDcIFJya14EXYmJkqse3XfBoezIaq8RpMLl3QgoI1aOvqCK304ymS KEKK/7bLzhtwQRFoCpBKlLRjCH2MVF72B0MsAGOwK2NuovB/xPxzoG92b78mhIyXr2nt 0rvHku8uURijhe35LAJQkCkuzePwmkFPa3EXznjIKyo071TtzrisnUeLuWUUGqQp1sEG uCEg== X-Gm-Message-State: AOAM53042bnP7pMkI0VonKa8xCGoYuES1MeCG7vew2r+IrekKapeP/ks +ePfIe6UlQtVp6p53OQ3GgM= X-Google-Smtp-Source: ABdhPJywpb2aGtJbMUBTz7dHBirLYndXq9uNXazWC4ByK4FHtHoZyXJNI3QQNh4eAvU69x7oIlMddQ== X-Received: by 2002:ae9:ef02:: with SMTP id d2mr1760318qkg.68.1605214065166; Thu, 12 Nov 2020 12:47:45 -0800 (PST) Received: from localhost.localdomain ([198.52.185.246]) by smtp.gmail.com with ESMTPSA id f61sm5369419qtb.75.2020.11.12.12.47.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2020 12:47:44 -0800 (PST) From: Sven Van Asbroeck X-Google-Original-From: Sven Van Asbroeck To: Jakub Kicinski , Bryan Whitehead , David S Miller Cc: Sven Van Asbroeck , Microchip Linux Driver Support , Andrew Lunn , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net v1] lan743x: prevent entire kernel HANG on open, for some platforms Date: Thu, 12 Nov 2020 15:47:41 -0500 Message-Id: <20201112204741.12375-1-TheSven73@gmail.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Sven Van Asbroeck On arm imx6, when opening the chip's netdev, the whole Linux kernel intermittently hangs/freezes. This is caused by a bug in the driver code which tests if pcie interrupts are working correctly, using the software interrupt: 1. open: enable the software interrupt 2. open: tell the chip to assert the software interrupt 3. open: wait for flag 4. ISR: acknowledge s/w interrupt, set flag 5. open: notice flag, disable the s/w interrupt, continue Unfortunately the ISR only acknowledges the s/w interrupt, but does not disable it. This will re-trigger the ISR in a tight loop. On some (lucky) platforms, open proceeds to disable the s/w interrupt even while the ISR is 'spinning'. On arm imx6, the spinning ISR does not allow open to proceed, resulting in a hung Linux kernel. Fix minimally by disabling the s/w interrupt in the ISR, which will prevent it from spinning. This won't break anything because the s/w interrupt is used as a one-shot interrupt. Note that this is a minimal fix, overlooking many possible cleanups, e.g.: - lan743x_intr_software_isr() is completely redundant and reads INT_STS twice for no apparent reason - disabling the s/w interrupt in lan743x_intr_test_isr() is now redundant, but harmless - waiting on software_isr_flag can be converted from a sleeping poll loop to wait_event_timeout() Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver") Tested-by: Sven Van Asbroeck # arm imx6 lan7430 Signed-off-by: Sven Van Asbroeck --- Tree: git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git # edbc21113bde To: Jakub Kicinski To: Bryan Whitehead To: "David S. Miller" Cc: Microchip Linux Driver Support Cc: Andrew Lunn Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org drivers/net/ethernet/microchip/lan743x_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c index 065e10bc98f2..f4a09e0f3ec5 100644 --- a/drivers/net/ethernet/microchip/lan743x_main.c +++ b/drivers/net/ethernet/microchip/lan743x_main.c @@ -148,7 +148,8 @@ static void lan743x_intr_software_isr(void *context) int_sts = lan743x_csr_read(adapter, INT_STS); if (int_sts & INT_BIT_SW_GP_) { - lan743x_csr_write(adapter, INT_STS, INT_BIT_SW_GP_); + /* disable the interrupt to prevent repeated re-triggering */ + lan743x_csr_write(adapter, INT_EN_CLR, INT_BIT_SW_GP_); intr->software_isr_flag = 1; } }