From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e9.ny.us.ibm.com (e9.ny.us.ibm.com [32.97.182.139]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e9.ny.us.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 13359B6EEF for ; Thu, 22 Mar 2012 05:58:21 +1100 (EST) Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 21 Mar 2012 14:58:17 -0400 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 42EA06E804F for ; Wed, 21 Mar 2012 14:58:13 -0400 (EDT) Received: from d03av03.boulder.ibm.com (d03av03.boulder.ibm.com [9.17.195.169]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q2LIwCG1307300 for ; Wed, 21 Mar 2012 14:58:12 -0400 Received: from d03av03.boulder.ibm.com (loopback [127.0.0.1]) by d03av03.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q2LIw8sv004490 for ; Wed, 21 Mar 2012 12:58:09 -0600 Subject: Re: [PATCH] Disable /dev/port interface on powerpc systems From: Haren Myneni To: Benjamin Herrenschmidt In-Reply-To: <1332314613.2982.38.camel@pasglop> References: <1332308237.23222.49.camel@hbabu-laptop> <1332314613.2982.38.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 21 Mar 2012 11:58:04 -0700 Message-ID: <1332356284.13004.9.camel@hbabu-laptop> Mime-Version: 1.0 Cc: linuxppc-dev@lists.ozlabs.org, anton@samba.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2012-03-21 at 18:23 +1100, Benjamin Herrenschmidt wrote: > On Tue, 2012-03-20 at 22:37 -0700, Haren Myneni wrote: > > Some power systems do not have legacy ISA devices. So, /dev/port is not > > a valid interface on these systems. User level tools such as kbdrate is > > trying to access the device using this interface which is causing the > > system crash. > > > > This patch will fix this issue by not creating this interface on these > > powerpc systems. > > Doesn't fix 32-bit... not a big deal for now I suppose... But I'd rather > you change the patch a tiny bit to change legacy_isa_device_found() to > arch_has_dev_port() instead. There may be other reason than legacy ISA > to enable dev/port or not so let's make the arch hook more generic. Thanks for your suggestions. I will make a change and re-post the patch. > > Another approach which might be even better is to filter per-access, > ie for each read/write to /dev/port, have a hook to check if that > specific port is valid, but that may be overkill for what is > essentially a legacy interface that should have died a long time ago :) Yes, can be changed open or read/write calls and return -ENODEV, but /dev/port is no use on these systems. I am not sure whether any power systems have legacy ISA devices. If we do not have, CONFIG_DEVPORT can be disabled in Kconfig. --- src/drivers/char/Kconfig.orig 2012-03-21 11:05:54.610010864 -0700 +++ src/drivers/char/Kconfig 2012-03-21 11:02:29.750009886 -0700 @@ -596,6 +596,7 @@ config DEVPORT bool depends on !M68K depends on ISA || PCI + depends on !PPC64 default y Thanks Haren > > Cheers, > Ben. > > > Signed-off-by: Haren Myneni > > > > > > diff -Naurp linux.orig/arch/powerpc/kernel/isa-bridge.c > > linux/arch/powerpc/kernel/isa-bridge.c > > --- linux.orig/arch/powerpc/kernel/isa-bridge.c 2012-02-11 > > 02:08:08.780005293 -0800 > > +++ linux/arch/powerpc/kernel/isa-bridge.c 2012-02-11 02:16:25.080003386 > > -0800 > > @@ -255,6 +255,14 @@ static struct notifier_block isa_bridge_ > > .notifier_call = isa_bridge_notify > > }; > > > > +int __init legacy_isa_device_found(void) > > +{ > > + if (isa_bridge_pcidev) > > + return 1; > > + > > + return 0; > > +} > > + > > /** > > * isa_bridge_init - register to be notified of ISA bridge > > addition/removal > > * > > diff -Naurp linux.orig/drivers/char/mem.c linux/drivers/char/mem.c > > --- linux.orig/drivers/char/mem.c 2012-02-11 02:08:42.710002440 -0800 > > +++ linux/drivers/char/mem.c 2012-03-20 20:40:43.650000003 -0700 > > @@ -35,6 +35,8 @@ > > # include > > #endif > > > > +#define DEVPORT_MINOR 4 > > + > > static inline unsigned long size_inside_page(unsigned long start, > > unsigned long size) > > { > > @@ -910,6 +912,11 @@ static char *mem_devnode(struct device * > > > > static struct class *mem_class; > > > > +int __init __weak legacy_isa_device_found(void) > > +{ > > + return 1; > > +} > > + > > static int __init chr_dev_init(void) > > { > > int minor; > > @@ -930,6 +937,13 @@ static int __init chr_dev_init(void) > > for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { > > if (!devlist[minor].name) > > continue; > > + > > + /* > > + * Create /dev/port? > > + */ > > + if ((minor == DEVPORT_MINOR) && !legacy_isa_device_found()) > > + continue; > > + > > device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), > > NULL, devlist[minor].name); > > } > > diff -Naurp linux.orig/include/linux/isa.h linux/include/linux/isa.h > > --- linux.orig/include/linux/isa.h 2012-02-11 02:07:52.030019810 -0800 > > +++ linux/include/linux/isa.h 2012-02-11 02:16:49.810002296 -0800 > > @@ -36,4 +36,5 @@ static inline void isa_unregister_driver > > } > > #endif > > > > +extern int __init legacy_isa_device_found(void); > > #endif /* __LINUX_ISA_H */ > > > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >