From patchwork Sun Mar 31 14:21:46 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Marek Vasut X-Patchwork-Id: 13612232 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 B27D774C1D for ; Sun, 31 Mar 2024 14:24:18 +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=1711895060; cv=none; b=mlJlQZwiNvdAymw3bylBrvMYZkAyTsNNnovyJeRTuzAOUEGrKDwWyJpQXubU+YNbt+q06HLdSYS6rIkbCNqjAQMeQWePqaL/XTI1MUjCGYLIkgKpkytTKkE5qKmGAz98rXc0AKedlIDM9LKNBdj+i7NTqbnf1WsKd8RR4DXEyS4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711895060; c=relaxed/simple; bh=RCq8ECneAcFQNthL3eafKXE5isa8/+3llJptkHIZvN8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=frT0iOwSGMY3MvG7lCFaRzI5BZ1F8V7B8Iwyymzfwf08vxCN0rXjMMBLD+QDrO+fLkeQ3e3bAiFxrlRQXvClDJnwITfP/dXvtEYfOB9mBUAx4NNC9NzyEw100YiI5jbLOzMUJihztbIkLkoYbfOwPM46LPhqO+e8jDd5nxUoTMY= 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=GDoiiD/F; 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="GDoiiD/F" 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 45EE087F5C; Sun, 31 Mar 2024 16:24:16 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=denx.de; s=phobos-20191101; t=1711895056; bh=6k5mc4z91Zj/OnKoK/eiEIlBfqwHMRyAIh8rhYTMJvU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GDoiiD/F8eyC0IAWdXjUpcBZVbophWl3Ca/Gvz89/YFn9PSqqlAfpQ+ZgaLKC77JV o30k3+OkG96b3uNazte0+CUc2+CX8wP0tc+AGhyo8eoO8AYLDfgfzoDQBRD3d0gxWn jAf2kkOt913XLbu5o/HVwnrx7aaNZVF8rj/K2BJOx/zem+kf7tekBFTYdNPkA5KiSn KdcghVrBUbAkiS8jIR5IN+bu8d6zE5v0QrPzfMzp15sSlSjaKuXpI7jJM2rBjHfFo/ lTaT5XpGZdkBDpVSrmSeejvlKJT2My8My4OeZvYwXsPN+UOIWv3BHZDjRK9Ozs335x tXXtww6ul+FMg== 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 , Ronald Wahl , Simon Horman Subject: [PATCH 2/2] net: ks8851: Handle softirqs at the end of IRQ thread to fix hang Date: Sun, 31 Mar 2024 16:21:46 +0200 Message-ID: <20240331142353.93792-2-marex@denx.de> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240331142353.93792-1-marex@denx.de> References: <20240331142353.93792-1-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: Ronald Wahl Cc: Simon Horman Cc: netdev@vger.kernel.org --- drivers/net/ethernet/micrel/ks8851_common.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/micrel/ks8851_common.c b/drivers/net/ethernet/micrel/ks8851_common.c index 896d43bb8883d..b6b727e651f3d 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; @@ -325,11 +325,15 @@ static void ks8851_rx_pkts(struct ks8851_net *ks) */ static irqreturn_t ks8851_irq(int irq, void *_ks) { + bool need_bh_off = !(hardirq_count() | softirq_count()); struct ks8851_net *ks = _ks; unsigned handled = 0; unsigned long flags; unsigned int status; + if (need_bh_off) + local_bh_disable(); + ks8851_lock(ks, &flags); status = ks8851_rdreg16(ks, KS_ISR); @@ -406,6 +410,9 @@ static irqreturn_t ks8851_irq(int irq, void *_ks) if (status & IRQ_LCI) mii_check_link(&ks->mii); + if (need_bh_off) + local_bh_enable(); + return IRQ_HANDLED; }