From: Andrew Morton <akpm@osdl.org>
To: matthieu castet <castet.matthieu@free.fr>
Cc: linux-kernel@vger.kernel.org, Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [patch] bug in cpuid & msr on nosmp machine
Date: Thu, 20 May 2004 00:32:40 -0700 [thread overview]
Message-ID: <20040520003240.75fd355d.akpm@osdl.org> (raw)
In-Reply-To: <40AB8CDF.8060408@free.fr>
matthieu castet <castet.matthieu@free.fr> wrote:
>
> on monocpu machine (and maybe even on smp machine), when you try to
> acces to a cpu that don't exist (/dev/cpu/1/cpuid), cpuid (msr) call
> cpu_online, but on nosmp machine if the cpu!=0 this procude a BUG();
> So I add a check that verify if the cpu can exist before calling cpu_online.
>
> Matthieu CASTET
>
>
> [cpuid.patch text/x-patch (589 bytes)]
> --- linux/arch/i386/kernel/cpuid.c 2004-05-18 20:47:05.000000000 +0200
> +++ linux-2.6.5/arch/i386/kernel/cpuid.c 2004-04-04 05:36:12.000000000 +0200
> @@ -135,7 +135,7 @@
> int cpu = iminor(file->f_dentry->d_inode);
> struct cpuinfo_x86 *c = &(cpu_data)[cpu];
>
> - if (cpu >= num_possible_cpus() || !cpu_online(cpu))
> + if (!cpu_online(cpu))
> return -ENXIO; /* No such CPU */
> if ( c->cpuid_level < 0 )
> return -EIO; /* CPUID not supported */
>
I think what you want here is
if (!cpu_possible(cpu) || !cpu_online(cpu))
return -ENXIO;
Like the below. Rusty agree?
--- 25/arch/i386/kernel/cpuid.c~cpuid-msr-range-checking-fix 2004-05-20 00:30:21.812166544 -0700
+++ 25-akpm/arch/i386/kernel/cpuid.c 2004-05-20 00:31:16.607836336 -0700
@@ -133,10 +133,12 @@ static ssize_t cpuid_read(struct file *f
static int cpuid_open(struct inode *inode, struct file *file)
{
int cpu = iminor(file->f_dentry->d_inode);
- struct cpuinfo_x86 *c = &(cpu_data)[cpu];
+ struct cpuinfo_x86 *c;
- if (!cpu_online(cpu))
+ if (!cpu_possible(cpu) || !cpu_online(cpu))
return -ENXIO; /* No such CPU */
+
+ c = &(cpu_data)[cpu];
if (c->cpuid_level < 0)
return -EIO; /* CPUID not supported */
diff -puN arch/i386/kernel/msr.c~cpuid-msr-range-checking-fix arch/i386/kernel/msr.c
--- 25/arch/i386/kernel/msr.c~cpuid-msr-range-checking-fix 2004-05-20 00:30:21.836162896 -0700
+++ 25-akpm/arch/i386/kernel/msr.c 2004-05-20 00:31:56.952702984 -0700
@@ -239,10 +239,12 @@ static ssize_t msr_write(struct file * f
static int msr_open(struct inode *inode, struct file *file)
{
int cpu = iminor(file->f_dentry->d_inode);
- struct cpuinfo_x86 *c = &(cpu_data)[cpu];
-
- if (!cpu_online(cpu))
- return -ENXIO; /* No such CPU */
+ struct cpuinfo_x86 *c;
+
+ if (!cpu_possible(cpu) || !cpu_online(cpu))
+ return -ENXIO; /* No such CPU */
+
+ c = &(cpu_data)[cpu];
if ( !cpu_has(c, X86_FEATURE_MSR) )
return -EIO; /* MSR not supported */
_
next prev parent reply other threads:[~2004-05-21 23:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-19 16:35 [patch] bug in cpuid & msr on nosmp machine matthieu castet
2004-05-19 17:46 ` matthieu castet
2004-05-20 2:44 ` Jeff Sipek
2004-05-20 9:51 ` Paul Jackson
2004-05-20 7:32 ` Andrew Morton [this message]
2004-05-20 8:34 ` Rusty Russell
2004-05-20 8:51 ` Andrew Morton
2004-05-20 9:30 ` Rusty Russell
2004-05-20 9:57 ` Rusty Russell
[not found] <1XCh4-1jO-67@gated-at.bofh.it>
[not found] ` <1XRg3-4LW-31@gated-at.bofh.it>
[not found] ` <1XRg3-4LW-29@gated-at.bofh.it>
[not found] ` <1XSc3-5y3-23@gated-at.bofh.it>
2004-05-22 8:13 ` Andi Kleen
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