From patchwork Fri Apr 5 20:30:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Marek Vasut X-Patchwork-Id: 13619395 X-Patchwork-Delegate: kuba@kernel.org Received: from phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D3D195672 for ; Fri, 5 Apr 2024 20:32:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=85.214.62.61 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712349157; cv=none; b=gYepRuKoo/BRVs9DwrbSWsqBE4oZalAYZDZB1LhQDocF38trPNyncAB3GUe7fK9h2nJbGmWharvDgoCI/IdtBnFY44NZF9DCXwuR/2XiKMvllZSgnJnNFJuZlDEtyqM1wMCbMoLGl2jDUC/LgAx77dDyYmHv2gGBxbAgBSdt8Zk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712349157; c=relaxed/simple; bh=y3mvKOywBfwdp7a542zuUR8+hlfS15XyGQ/EUsitUCo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=otUphEX8Jp/Vjkfj8mOBIN6Cjtu7JfWNe+F/tpv3Pvbd+m/lxDJnr3byJe44MNJIUeFH7ZBJ70cj0fbxkYLbvA7V6KHNA7Pxcf4SaWbx54a+OKtUws1AloWZLQ8tVl9qzMeeh65OyqV5mNV1JkToyUlNQMZJNp0ZXk4jSKAdU7o= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=denx.de; spf=pass smtp.mailfrom=denx.de; dkim=pass (2048-bit key) header.d=denx.de header.i=@denx.de header.b=E7+TkIBz; arc=none smtp.client-ip=85.214.62.61 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=denx.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=denx.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=denx.de header.i=@denx.de header.b="E7+TkIBz" Received: from tr.lan (ip-86-49-120-218.bb.vodafone.cz [86.49.120.218]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: marex@denx.de) by phobos.denx.de (Postfix) with ESMTPSA id 4C52D87FA3; Fri, 5 Apr 2024 22:32:33 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=denx.de; s=phobos-20191101; t=1712349153; bh=xyWgVztm1k+nhEoZlniLnlJpzeazj9/DBcSn8/ZOvVo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E7+TkIBzF3BMgYkn93V/mTu/wiiex6tycVb2EyJT7rWdvE9aqThtDAkTPcB2+nSuF Hbv3kKvn0Weok4EJWLKLpmQ4gtYMPfYQT9nxIrD1AcxTuc6FV2FtsoUQyWVc0+2LKb UrR9E/sIMrJyfy99ByDDaX/EOpE4Kz5BfupClFFKy/TMuxLRz+xurCxx4bUcSihv5I WIonoXGcP1wwfAicWVsrFucvXwk7CKcTRBohcwzz3oH7l2KiG8q6z4VV/M8tBm2LNH KNJCDQnKq1D/d0aWLVlxO/ioXfBJFM2SjLTcN07Ey3Z1V4i5KCHSqXIlGHg038Rk+8 3rdtXcQJAQlnA== From: Marek Vasut To: netdev@vger.kernel.org Cc: Marek Vasut , "David S. Miller" , =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Andy Shevchenko , Dmitry Torokhov , Eric Dumazet , Jakub Kicinski , Mark Brown , Paolo Abeni , Ratheesh Kannoth , Ronald Wahl , Simon Horman Subject: [PATCH net v2 2/2] net: ks8851: Handle softirqs at the end of IRQ thread to fix hang Date: Fri, 5 Apr 2024 22:30:40 +0200 Message-ID: <20240405203204.82062-2-marex@denx.de> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240405203204.82062-1-marex@denx.de> References: <20240405203204.82062-1-marex@denx.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.103.8 at phobos.denx.de X-Virus-Status: Clean X-Patchwork-Delegate: kuba@kernel.org The ks8851_irq() thread may call ks8851_rx_pkts() in case there are any packets in the MAC FIFO, which calls netif_rx(). This netif_rx() implementation is guarded by local_bh_disable() and local_bh_enable(). The local_bh_enable() may call do_softirq() to run softirqs in case any are pending. One of the softirqs is net_rx_action, which ultimately reaches the driver .start_xmit callback. If that happens, the system hangs. The entire call chain is below: ks8851_start_xmit_par from netdev_start_xmit netdev_start_xmit from dev_hard_start_xmit dev_hard_start_xmit from sch_direct_xmit sch_direct_xmit from __dev_queue_xmit __dev_queue_xmit from __neigh_update __neigh_update from neigh_update neigh_update from arp_process.constprop.0 arp_process.constprop.0 from __netif_receive_skb_one_core __netif_receive_skb_one_core from process_backlog process_backlog from __napi_poll.constprop.0 __napi_poll.constprop.0 from net_rx_action net_rx_action from __do_softirq __do_softirq from call_with_stack call_with_stack from do_softirq do_softirq from __local_bh_enable_ip __local_bh_enable_ip from netif_rx netif_rx from ks8851_irq ks8851_irq from irq_thread_fn irq_thread_fn from irq_thread irq_thread from kthread kthread from ret_from_fork The hang happens because ks8851_irq() first locks a spinlock in ks8851_par.c ks8851_lock_par() spin_lock_irqsave(&ksp->lock, ...) and with that spinlock locked, calls netif_rx(). Once the execution reaches ks8851_start_xmit_par(), it calls ks8851_lock_par() again which attempts to claim the already locked spinlock again, and the hang happens. Move the do_softirq() call outside of the spinlock protected section of ks8851_irq() by disabling BHs around the entire spinlock protected section of ks8851_irq() handler. Place local_bh_enable() outside of the spinlock protected section, so that it can trigger do_softirq() without the ks8851_par.c ks8851_lock_par() spinlock being held, and safely call ks8851_start_xmit_par() without attempting to lock the already locked spinlock. Since ks8851_irq() is protected by local_bh_disable()/local_bh_enable() now, replace netif_rx() with __netif_rx() which is not duplicating the local_bh_disable()/local_bh_enable() calls. Fixes: 797047f875b5 ("net: ks8851: Implement Parallel bus operations") Signed-off-by: Marek Vasut --- Cc: "David S. Miller" Cc: "Uwe Kleine-König" Cc: Andy Shevchenko Cc: Dmitry Torokhov Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Mark Brown Cc: Paolo Abeni Cc: Ratheesh Kannoth Cc: Ronald Wahl Cc: Simon Horman Cc: netdev@vger.kernel.org --- V2: - Drop the need_bh_off test, the test was always true - Fill in 'net' subject prefix --- drivers/net/ethernet/micrel/ks8851_common.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/micrel/ks8851_common.c b/drivers/net/ethernet/micrel/ks8851_common.c index 896d43bb8883d..d4cdf3d4f5525 100644 --- a/drivers/net/ethernet/micrel/ks8851_common.c +++ b/drivers/net/ethernet/micrel/ks8851_common.c @@ -299,7 +299,7 @@ static void ks8851_rx_pkts(struct ks8851_net *ks) ks8851_dbg_dumpkkt(ks, rxpkt); skb->protocol = eth_type_trans(skb, ks->netdev); - netif_rx(skb); + __netif_rx(skb); ks->netdev->stats.rx_packets++; ks->netdev->stats.rx_bytes += rxlen; @@ -330,6 +330,8 @@ static irqreturn_t ks8851_irq(int irq, void *_ks) unsigned long flags; unsigned int status; + local_bh_disable(); + ks8851_lock(ks, &flags); status = ks8851_rdreg16(ks, KS_ISR); @@ -406,6 +408,8 @@ static irqreturn_t ks8851_irq(int irq, void *_ks) if (status & IRQ_LCI) mii_check_link(&ks->mii); + local_bh_enable(); + return IRQ_HANDLED; }