From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752275AbdLDP0j (ORCPT ); Mon, 4 Dec 2017 10:26:39 -0500 Received: from aer-iport-3.cisco.com ([173.38.203.53]:43798 "EHLO aer-iport-3.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751033AbdLDP0e (ORCPT ); Mon, 4 Dec 2017 10:26:34 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0BxAQC1aCVa/xbLJq1cGQEBAQEBAQEBA?= =?us-ascii?q?QEBAQcBAQEBAYM8RoEOJ48TkH6WA4IVCoU7hXYWAQEBAQEBAQEBayiFUFKBUYo?= =?us-ascii?q?iqWA6ilQBAQgohyeBaYJ1hiOFLAWSBpBmlQQNk1aWIAIEBgUCGQGBOiYOJIFNM?= =?us-ascii?q?hoIGxU6gimCUhyBaT83ihoBAQE?= X-IronPort-AV: E=Sophos;i="5.45,359,1508803200"; d="scan'208";a="634404" From: Denys Zagorui To: gregkh@linuxfoundation.org Cc: jslaby@suse.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] serial: 8250: convert to threaded IRQ Date: Mon, 4 Dec 2017 17:26:27 +0200 Message-Id: <20171204152627.23906-1-dzagorui@cisco.com> X-Mailer: git-send-email 2.11.0 X-Authenticated-User: dzagorui@cisco.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During using virtualization it is common to see many "too much work for irq*" messages. There are fixes proposed erlier: - e7328ae1848966181a7ac47e8ae6cddbd2cf55f3 (serial: 8250, increase PASS_LIMIT) - f4f653e9875e573860e783fecbebde284a8626f5 (serial: 8250, disable "too much work" messages First one doesn't help now, last one was reverted (12de375ec493ab1767d4a07dde823e63ae5edc21) in fact it doesn't fix anything. So procesing interrupts in kthread give us an opportunity to perform rescheduling periodically. Cc: Jiri Slaby Signed-off-by: Denys Zagorui --- v1 -> v2: - Fix spin-lock inconsistent usage. - After rescheduling check that all ports have been serviced again. v2 -> v3: - Add changelog. drivers/tty/serial/8250/8250_core.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 9342fc2ee7df..20d8e5fe2dc4 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -54,7 +54,7 @@ static struct uart_driver serial8250_reg; static unsigned int skip_txen_test; /* force skip of txen test at init time */ -#define PASS_LIMIT 512 +#define PASS_LIMIT 32 #include /* @@ -131,10 +131,13 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id) l = l->next; if (l == i->head && pass_counter++ > PASS_LIMIT) { - /* If we hit this, we're dead. */ - printk_ratelimited(KERN_ERR - "serial8250: too much work for irq%d\n", irq); - break; + spin_unlock(&i->lock); + cond_resched(); + spin_lock(&i->lock); + end = NULL; + l = i->head; + pass_counter = 0; + continue; } } while (l != end); @@ -142,9 +145,20 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id) pr_debug("%s(%d): end\n", __func__, irq); + enable_irq(i->irq); + return IRQ_RETVAL(handled); } +static irqreturn_t serial8250_hard_irq(int irq, void *dev_id) +{ + struct irq_info *i = dev_id; + + disable_irq_nosync(i->irq); + + return IRQ_WAKE_THREAD; +} + /* * To support ISA shared interrupts, we need to have one interrupt * handler that ensures that the IRQ line has been deasserted @@ -213,8 +227,8 @@ static int serial_link_irq_chain(struct uart_8250_port *up) i->head = &up->list; spin_unlock_irq(&i->lock); irq_flags |= up->port.irqflags; - ret = request_irq(up->port.irq, serial8250_interrupt, - irq_flags, up->port.name, i); + ret = request_threaded_irq(up->port.irq, serial8250_hard_irq, + serial8250_interrupt, irq_flags, up->port.name, i); if (ret < 0) serial_do_unlink(i, up); } -- 2.11.0