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 X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CA6C9C71156 for ; Mon, 23 Nov 2020 12:31:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7EF1E2076E for ; Mon, 23 Nov 2020 12:31:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="zai45BnD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730804AbgKWMa7 (ORCPT ); Mon, 23 Nov 2020 07:30:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:41870 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730799AbgKWMa7 (ORCPT ); Mon, 23 Nov 2020 07:30:59 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1E43220728; Mon, 23 Nov 2020 12:30:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1606134658; bh=oWESSb/KESHk/7RZ6Qu/BgrRa8Q1K148M9X3dlhSkyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zai45BnD8cd3HRYWnouPTR0NguEVxX34Q8/IO3RTdSnpbQZCCQ1RpI0dyRUMc/RB6 JNl4mGmBcZVoP/F7VUlZeJyfXTwvONaKIPirXQvxUT8QS2cyb9rgYvoOfK+VF7QmQ3 dT5kGGoBr2OcMQ7EOUUHoUPkTJTsw2C98ZGBYFZ4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sven Van Asbroeck , Jakub Kicinski Subject: [PATCH 4.19 07/91] lan743x: prevent entire kernel HANG on open, for some platforms Date: Mon, 23 Nov 2020 13:21:27 +0100 Message-Id: <20201123121809.660731035@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201123121809.285416732@linuxfoundation.org> References: <20201123121809.285416732@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sven Van Asbroeck [ Upstream commit 796a2665ca3e91ebaba7222f76fd9a035714e2d8 ] 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 Link: https://lore.kernel.org/r/20201112204741.12375-1-TheSven73@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/microchip/lan743x_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/net/ethernet/microchip/lan743x_main.c +++ b/drivers/net/ethernet/microchip/lan743x_main.c @@ -145,7 +145,8 @@ static void lan743x_intr_software_isr(vo 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; } }