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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 56F51C433E0 for ; Fri, 12 Feb 2021 00:09:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D6CC64E4A for ; Fri, 12 Feb 2021 00:09:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229743AbhBLAJL (ORCPT ); Thu, 11 Feb 2021 19:09:11 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:53176 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229623AbhBLAJK (ORCPT ); Thu, 11 Feb 2021 19:09:10 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by kvm5.telegraphics.com.au (Postfix) with ESMTP id 41E282AC50; Thu, 11 Feb 2021 19:08:26 -0500 (EST) Date: Fri, 12 Feb 2021 11:08:33 +1100 (AEDT) From: Finn Thain To: "Song Bao Hua (Barry Song)" cc: tanxiaofei , "jejb@linux.ibm.com" , "martin.petersen@oracle.com" , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linuxarm@openeuler.org" , "linux-m68k@vger.kernel.org" Subject: RE: Re: [PATCH for-next 00/32] spin lock usage optimization for SCSI drivers In-Reply-To: <0d104f0e26134b1ea9c530be895e65d1@hisilicon.com> Message-ID: <4dcf1410-768e-ae95-33bf-cba093b0751d@telegraphics.com.au> References: <417fa728c3ff4418ac87e0d409b5a084@hisilicon.com> <0d104f0e26134b1ea9c530be895e65d1@hisilicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org On Fri, 12 Feb 2021, Song Bao Hua (Barry Song) wrote: > > > -----Original Message----- > > From: Finn Thain [mailto:fthain@telegraphics.com.au] > > Sent: Friday, February 12, 2021 12:57 PM > > To: Song Bao Hua (Barry Song) > > Cc: tanxiaofei ; jejb@linux.ibm.com; > > martin.petersen@oracle.com; linux-scsi@vger.kernel.org; > > linux-kernel@vger.kernel.org; linuxarm@openeuler.org; > > linux-m68k@vger.kernel.org > > Subject: RE: Re: [PATCH for-next 00/32] spin lock usage optimization for SCSI > > drivers > > > > > > On Thu, 11 Feb 2021, Song Bao Hua (Barry Song) wrote: > > > > > > > > Actually in m68k, I also saw its IRQ entry disabled interrupts by > > > ' move #0x2700,%sr /* disable intrs */' > > > > > > arch/m68k/include/asm/entry.h: > > > > > > .macro SAVE_ALL_SYS > > > move #0x2700,%sr /* disable intrs */ > > > btst #5,%sp@(2) /* from user? */ > > > bnes 6f /* no, skip */ > > > movel %sp,sw_usp /* save user sp */ > > > ... > > > > > > .macro SAVE_ALL_INT > > > SAVE_ALL_SYS > > > moveq #-1,%d0 /* not system call entry */ > > > movel %d0,%sp@(PT_OFF_ORIG_D0) > > > .endm > > > > > > arch/m68k/kernel/entry.S: > > > > > > /* This is the main interrupt handler for autovector interrupts */ > > > > > > ENTRY(auto_inthandler) > > > SAVE_ALL_INT > > > GET_CURRENT(%d0) > > > | put exception # in d0 > > > bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0 > > > subw #VEC_SPUR,%d0 > > > > > > movel %sp,%sp@- > > > movel %d0,%sp@- | put vector # on stack > > > auto_irqhandler_fixup = . + 2 > > > jsr do_IRQ | process the IRQ > > > addql #8,%sp | pop parameters off stack > > > jra ret_from_exception > > > > > > So my question is that " move #0x2700,%sr" is actually disabling > > > all interrupts? And is m68k actually running irq handlers > > > with interrupts disabled? > > > > > > > When sonic_interrupt() executes, the IPL is 2 or 3 (since either IRQ may > > be involved). That is, SR & 0x700 is 0x200 or 0x300. The level 3 interrupt > > may interrupt execution of the level 2 handler so an irq lock is used to > > avoid re-entrance. > > > > This patch, > > > > diff --git a/drivers/net/ethernet/natsemi/sonic.c > > b/drivers/net/ethernet/natsemi/sonic.c > > index d17d1b4f2585..041354647bad 100644 > > --- a/drivers/net/ethernet/natsemi/sonic.c > > +++ b/drivers/net/ethernet/natsemi/sonic.c > > @@ -355,6 +355,8 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id) > > */ > > spin_lock_irqsave(&lp->lock, flags); > > > > + printk_once(KERN_INFO "%s: %08lx\n", __func__, flags); > > + > > status = SONIC_READ(SONIC_ISR) & SONIC_IMR_DEFAULT; > > if (!status) { > > spin_unlock_irqrestore(&lp->lock, flags); > > > > produces this output, > > > > [ 3.800000] sonic_interrupt: 00002300 > > I actually hope you can directly read the register rather than reading > a flag which might be a software one not from register. > Again, the implementation of arch_local_irq_save() may be found in arch/m68k/include/asm/irqflags.h > > > > I ran that code in QEMU, but experience shows that Apple hardware works > > exactly the same. Please do confirm this for yourself, if you still think > > the code and comments in sonic_interrupt are wrong. > > > > > Best Regards > > > Barry > > > > > Thanks > Barry > >