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=-7.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 A3B85C4727F for ; Sun, 27 Sep 2020 20:01:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62BFD22207 for ; Sun, 27 Sep 2020 20:01:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="PcTPGmyn"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="HW82wROg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727174AbgI0UA5 (ORCPT ); Sun, 27 Sep 2020 16:00:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727049AbgI0T50 (ORCPT ); Sun, 27 Sep 2020 15:57:26 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFB49C0613D6; Sun, 27 Sep 2020 12:57:25 -0700 (PDT) Message-Id: <20200927194921.344476620@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1601236644; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=zSaSCj9Lkxu4/pcxMR81Hr3g1YwRhUy6jZEIpStU97M=; b=PcTPGmyn+7ilzainipblbRFvODqGUQvMaNV94fvbYEfNqsVCPg/cowPt1kZO+op6hlsmX9 LzxggLRNI8vuoxsZw1VR3YIF8ETp+fDQPfYMj+V5kAs27G5M6/CQvJtQqiJPeqJYQAOlz0 XqHG82dmNHX3ypjyehoRugJGCu9pcSm+GITns2K0CPrypjShvVaESPH5lP2LHQ8qVFRRl1 haxkNPDk2xDCkZqwuxdVS0/UBNr/Jj1ANnMKXHmifYcj71fidmJuPTRJgi7zQPw0t8Lmh+ 4NXz5Yf2+H0Y6ANZIYneBnDbjmSBdWL//QN6el3aDF+pMWXMc2+w6BrqJWs9gQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1601236644; 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: content-transfer-encoding:content-transfer-encoding: references:references; bh=zSaSCj9Lkxu4/pcxMR81Hr3g1YwRhUy6jZEIpStU97M=; b=HW82wROg+eV51ogDnTUAcxBWmVh3qs8TCjxdc12awvPmZTJ0k6XtQyWTH472kLtKEUa1l+ Rm4E8/1CcD+McSCQ== Date: Sun, 27 Sep 2020 21:49:01 +0200 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Linus Torvalds , Paul McKenney , Matthew Wilcox , Sebastian Andrzej Siewior , Solarflare linux maintainers , Edward Cree , Martin Habets , "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, Christian Benvenuti , Govindarajulu Varadarajan <_govind@gmx.com>, Dave Miller , Jonathan Corbet , Mauro Carvalho Chehab , linux-doc@vger.kernel.org, Luc Van Oostenryck , Jay Cliburn , Chris Snook , Vishal Kulkarni , Jeff Kirsher , intel-wired-lan@lists.osuosl.org, Shannon Nelson , Pensando Drivers , Andrew Lunn , Heiner Kallweit , Russell King , Thomas Bogendoerfer , Jon Mason , Daniel Drake , Ulrich Kunitz , Kalle Valo , linux-wireless@vger.kernel.org, linux-usb@vger.kernel.org, Greg Kroah-Hartman , Arend van Spriel , Franky Lin , Hante Meuleman , Chi-Hsien Lin , Wright Feng , brcm80211-dev-list.pdl@broadcom.com, brcm80211-dev-list@cypress.com, Stanislav Yakovlev , Stanislaw Gruszka , Johannes Berg , Emmanuel Grumbach , Luca Coelho , Intel Linux Wireless , Jouni Malinen , Amitkumar Karwar , Ganapathi Bhat , Xinming Hu , libertas-dev@lists.infradead.org, Pascal Terjan , Ping-Ke Shih Subject: [patch 15/35] net: sfc: Replace in_interrupt() usage. References: <20200927194846.045411263@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sebastian Andrzej Siewior efx_ef10_try_update_nic_stats_vf() uses in_interrupt() to figure out whether it is safe to sleep or not. The following callers are involved: - efx_start_all() and efx_stop_all() are fully preemptible because a mutex is acquired near by. - efx_ethtool_get_stats() is ivoked from ethtool_ops->get_ethtool_stats() and is fully preemptible. - efx_net_stats() which can be invoked under dev_base_lock from net-sysfs::netstat_show(). dev_base_lock is a rwlock_t which disables preemption implicitly. in_interrupt() cannot detect context which has only preemption disabled so the check fails to detect that this calling context is not safe to sleep. Obviously this is a bug and clearly this has never been tested with any of the relevant and mandatory debug options enabled, which would have caught it. Changing the condition to preemptible() is not useful either because on CONFIG_PREEMPT_COUNT=n kernels preemptible() is useless. Aside of that Linus clearly requested that functions which change their behaviour depending on execution context should either be split up or the callers provide context information via an argument. Add a 'can_sleep' argument to efx_ef10_try_update_nic_stats_vf() and let the callers indicate the context from which this is called. Another oddity of that code is that it uses GFP_ATOMIC _after_ establishing that the context is safe to sleep. Convert it to GFP_KERNEL while at it. Note, that the fixes tag is empty as it is unclear which of the commits to blame. Fixes: ???? Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Cc: Solarflare linux maintainers Cc: Edward Cree Cc: Martin Habets Cc: "David S. Miller" Cc: Jakub Kicinski Cc: netdev@vger.kernel.org --- drivers/net/ethernet/sfc/ef10.c | 18 +++++++++--------- drivers/net/ethernet/sfc/ef100_nic.c | 3 ++- drivers/net/ethernet/sfc/efx_common.c | 6 +++--- drivers/net/ethernet/sfc/ethtool_common.c | 2 +- drivers/net/ethernet/sfc/net_driver.h | 3 ++- drivers/net/ethernet/sfc/siena.c | 3 ++- 6 files changed, 19 insertions(+), 16 deletions(-) --- a/drivers/net/ethernet/sfc/ef10.c +++ b/drivers/net/ethernet/sfc/ef10.c @@ -1797,7 +1797,8 @@ static size_t efx_ef10_update_stats_comm } static size_t efx_ef10_update_stats_pf(struct efx_nic *efx, u64 *full_stats, - struct rtnl_link_stats64 *core_stats) + struct rtnl_link_stats64 *core_stats, + bool can_sleep) { struct efx_ef10_nic_data *nic_data = efx->nic_data; DECLARE_BITMAP(mask, EF10_STAT_COUNT); @@ -1836,7 +1837,7 @@ static size_t efx_ef10_update_stats_pf(s return efx_ef10_update_stats_common(efx, full_stats, core_stats); } -static int efx_ef10_try_update_nic_stats_vf(struct efx_nic *efx) +static int efx_ef10_try_update_nic_stats_vf(struct efx_nic *efx, bool can_sleep) __must_hold(&efx->stats_lock) { MCDI_DECLARE_BUF(inbuf, MC_CMD_MAC_STATS_IN_LEN); @@ -1849,20 +1850,18 @@ static int efx_ef10_try_update_nic_stats __le64 *dma_stats; int rc; - spin_unlock_bh(&efx->stats_lock); - - if (in_interrupt()) { + if (!can_sleep) { /* If in atomic context, cannot update stats. Just update the * software stats and return so the caller can continue. */ - spin_lock_bh(&efx->stats_lock); efx_update_sw_stats(efx, stats); return 0; } + spin_unlock_bh(&efx->stats_lock); efx_ef10_get_stat_mask(efx, mask); - rc = efx_nic_alloc_buffer(efx, &stats_buf, dma_len, GFP_ATOMIC); + rc = efx_nic_alloc_buffer(efx, &stats_buf, dma_len, GFP_KERNEL); if (rc) { spin_lock_bh(&efx->stats_lock); return rc; @@ -1910,9 +1909,10 @@ static int efx_ef10_try_update_nic_stats } static size_t efx_ef10_update_stats_vf(struct efx_nic *efx, u64 *full_stats, - struct rtnl_link_stats64 *core_stats) + struct rtnl_link_stats64 *core_stats, + bool can_sleep) { - if (efx_ef10_try_update_nic_stats_vf(efx)) + if (efx_ef10_try_update_nic_stats_vf(efx, can_sleep)) return 0; return efx_ef10_update_stats_common(efx, full_stats, core_stats); --- a/drivers/net/ethernet/sfc/ef100_nic.c +++ b/drivers/net/ethernet/sfc/ef100_nic.c @@ -599,7 +599,8 @@ static size_t ef100_update_stats_common( static size_t ef100_update_stats(struct efx_nic *efx, u64 *full_stats, - struct rtnl_link_stats64 *core_stats) + struct rtnl_link_stats64 *core_stats, + bool can_sleep) { __le64 *mc_stats = kmalloc(array_size(efx->num_mac_stats, sizeof(__le64)), GFP_ATOMIC); struct ef100_nic_data *nic_data = efx->nic_data; --- a/drivers/net/ethernet/sfc/efx_common.c +++ b/drivers/net/ethernet/sfc/efx_common.c @@ -552,7 +552,7 @@ void efx_start_all(struct efx_nic *efx) efx->type->start_stats(efx); efx->type->pull_stats(efx); spin_lock_bh(&efx->stats_lock); - efx->type->update_stats(efx, NULL, NULL); + efx->type->update_stats(efx, NULL, NULL, true); spin_unlock_bh(&efx->stats_lock); } } @@ -576,7 +576,7 @@ void efx_stop_all(struct efx_nic *efx) */ efx->type->pull_stats(efx); spin_lock_bh(&efx->stats_lock); - efx->type->update_stats(efx, NULL, NULL); + efx->type->update_stats(efx, NULL, NULL, true); spin_unlock_bh(&efx->stats_lock); efx->type->stop_stats(efx); } @@ -600,7 +600,7 @@ void efx_net_stats(struct net_device *ne struct efx_nic *efx = netdev_priv(net_dev); spin_lock_bh(&efx->stats_lock); - efx->type->update_stats(efx, NULL, stats); + efx->type->update_stats(efx, NULL, stats, false); spin_unlock_bh(&efx->stats_lock); } --- a/drivers/net/ethernet/sfc/ethtool_common.c +++ b/drivers/net/ethernet/sfc/ethtool_common.c @@ -502,7 +502,7 @@ void efx_ethtool_get_stats(struct net_de spin_lock_bh(&efx->stats_lock); /* Get NIC statistics */ - data += efx->type->update_stats(efx, data, NULL); + data += efx->type->update_stats(efx, data, NULL, true); /* Get software statistics */ for (i = 0; i < EFX_ETHTOOL_SW_STAT_COUNT; i++) { --- a/drivers/net/ethernet/sfc/net_driver.h +++ b/drivers/net/ethernet/sfc/net_driver.h @@ -1358,7 +1358,8 @@ struct efx_nic_type { void (*finish_flr)(struct efx_nic *efx); size_t (*describe_stats)(struct efx_nic *efx, u8 *names); size_t (*update_stats)(struct efx_nic *efx, u64 *full_stats, - struct rtnl_link_stats64 *core_stats); + struct rtnl_link_stats64 *core_stats, + bool can_sleep); void (*start_stats)(struct efx_nic *efx); void (*pull_stats)(struct efx_nic *efx); void (*stop_stats)(struct efx_nic *efx); --- a/drivers/net/ethernet/sfc/siena.c +++ b/drivers/net/ethernet/sfc/siena.c @@ -587,7 +587,8 @@ static int siena_try_update_nic_stats(st } static size_t siena_update_nic_stats(struct efx_nic *efx, u64 *full_stats, - struct rtnl_link_stats64 *core_stats) + struct rtnl_link_stats64 *core_stats, + bool can_sleep) { struct siena_nic_data *nic_data = efx->nic_data; u64 *stats = nic_data->stats;