Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756446AbcCBARR (ORCPT ); Tue, 1 Mar 2016 19:17:17 -0500 Received: from mail333.us4.mandrillapp.com ([205.201.137.77]:58697 "EHLO mail333.us4.mandrillapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932405AbcCAX6F (ORCPT ); Tue, 1 Mar 2016 18:58:05 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; q=dns; s=mandrill; d=linuxfoundation.org; b=kOMKu+y94poGiL97jSuQdJe0Od+6k7lKTSwxCFVcT0UutM8XsrAfojV/e1G32MBV3Qclj7TTy4Ey WrYlIPNC9u3SAiT7A7sV4DgZ8MWFQjO4odrtU8ujXTEfXLa7iByVdcL4RKH+JmSnNauMCMXGdBBK FZQ9QvJOENd1dmjUypk=; From: Greg Kroah-Hartman Subject: [PATCH 4.4 288/342] ARCv2: SMP: Emulate IPI to self using software triggered interrupt X-Mailer: git-send-email 2.7.2 To: Cc: Greg Kroah-Hartman , , Peter Zijlstra , Vineet Gupta Message-Id: <20160301234537.208854858@linuxfoundation.org> In-Reply-To: <20160301234527.990448862@linuxfoundation.org> References: <20160301234527.990448862@linuxfoundation.org> X-Report-Abuse: Please forward a copy of this message, including all headers, to abuse@mandrill.com X-Report-Abuse: You can also report abuse here: http://mandrillapp.com/contact/abuse?id=30481620.2b533a70a6224168872607918fa8d708 X-Mandrill-User: md_30481620 Date: Tue, 01 Mar 2016 23:55:20 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4165 Lines: 131 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vineet Gupta commit bb143f814ea488769ca2e79e0b376139cb5f134b upstream. ARConnect/MCIP Inter-Core-Interrupt module can't send interrupt to local core. So use core intc capability to trigger software interrupt to self, using an unsued IRQ #21. This showed up as csd deadlock with LTP trace_sched on a dual core system. This test acts as scheduler fuzzer, triggering all sorts of schedulting activity. Trouble starts with IPI to self, which doesn't get delivered (effectively lost due to H/w capability), but the msg intended to be sent remain enqueued in per-cpu @ipi_data. All subsequent IPIs to this core from other cores get elided due to the IPI coalescing optimization in ipi_send_msg_one() where a pending msg implies an IPI already sent and assumes other core is yet to ack it. After the elided IPI, other core simply goes into csd_lock_wait() but never comes out as this core never sees the interrupt. Fixes STAR 9001008624 Cc: Peter Zijlstra Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman --- arch/arc/include/asm/irqflags-arcv2.h | 11 +++++++++++ arch/arc/kernel/entry-arcv2.S | 11 ++++++----- arch/arc/kernel/mcip.c | 15 +++++++++++++++ 3 files changed, 32 insertions(+), 5 deletions(-) --- a/arch/arc/include/asm/irqflags-arcv2.h +++ b/arch/arc/include/asm/irqflags-arcv2.h @@ -22,6 +22,7 @@ #define AUX_IRQ_CTRL 0x00E #define AUX_IRQ_ACT 0x043 /* Active Intr across all levels */ #define AUX_IRQ_LVL_PEND 0x200 /* Pending Intr across all levels */ +#define AUX_IRQ_HINT 0x201 /* For generating Soft Interrupts */ #define AUX_IRQ_PRIORITY 0x206 #define ICAUSE 0x40a #define AUX_IRQ_SELECT 0x40b @@ -112,6 +113,16 @@ static inline int arch_irqs_disabled(voi return arch_irqs_disabled_flags(arch_local_save_flags()); } +static inline void arc_softirq_trigger(int irq) +{ + write_aux_reg(AUX_IRQ_HINT, irq); +} + +static inline void arc_softirq_clear(int irq) +{ + write_aux_reg(AUX_IRQ_HINT, 0); +} + #else .macro IRQ_DISABLE scratch --- a/arch/arc/kernel/entry-arcv2.S +++ b/arch/arc/kernel/entry-arcv2.S @@ -45,11 +45,12 @@ VECTOR reserved ; Reserved slots VECTOR handle_interrupt ; (16) Timer0 VECTOR handle_interrupt ; unused (Timer1) VECTOR handle_interrupt ; unused (WDT) -VECTOR handle_interrupt ; (19) ICI (inter core interrupt) -VECTOR handle_interrupt -VECTOR handle_interrupt -VECTOR handle_interrupt -VECTOR handle_interrupt ; (23) End of fixed IRQs +VECTOR handle_interrupt ; (19) Inter core Interrupt (IPI) +VECTOR handle_interrupt ; (20) perf Interrupt +VECTOR handle_interrupt ; (21) Software Triggered Intr (Self IPI) +VECTOR handle_interrupt ; unused +VECTOR handle_interrupt ; (23) unused +# End of fixed IRQs .rept CONFIG_ARC_NUMBER_OF_INTERRUPTS - 8 VECTOR handle_interrupt --- a/arch/arc/kernel/mcip.c +++ b/arch/arc/kernel/mcip.c @@ -11,9 +11,12 @@ #include #include #include +#include #include #include +#define SOFTIRQ_IRQ 21 + static char smp_cpuinfo_buf[128]; static int idu_detected; @@ -22,6 +25,7 @@ static DEFINE_RAW_SPINLOCK(mcip_lock); static void mcip_setup_per_cpu(int cpu) { smp_ipi_irq_setup(cpu, IPI_IRQ); + smp_ipi_irq_setup(cpu, SOFTIRQ_IRQ); } static void mcip_ipi_send(int cpu) @@ -29,6 +33,12 @@ static void mcip_ipi_send(int cpu) unsigned long flags; int ipi_was_pending; + /* ARConnect can only send IPI to others */ + if (unlikely(cpu == raw_smp_processor_id())) { + arc_softirq_trigger(SOFTIRQ_IRQ); + return; + } + /* * NOTE: We must spin here if the other cpu hasn't yet * serviced a previous message. This can burn lots @@ -63,6 +73,11 @@ static void mcip_ipi_clear(int irq) unsigned long flags; unsigned int __maybe_unused copy; + if (unlikely(irq == SOFTIRQ_IRQ)) { + arc_softirq_clear(irq); + return; + } + raw_spin_lock_irqsave(&mcip_lock, flags); /* Who sent the IPI */