| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Thu, 19 Apr 2012 13:02:29 +0200
From: Borislav Petkov <bp@...64.org>
To: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc: Dan Carpenter <dan.carpenter@...cle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Frank Arnold <frank.arnold@....com>,
linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch] cpu: remove some dead code in store_cache_disable()
On Thu, Apr 19, 2012 at 01:48:02PM +0530, Srivatsa S. Bhat wrote:
> On 04/19/2012 12:30 PM, Dan Carpenter wrote:
>
> > amd_set_l3_disable_slot() never returns -EEXIST, it only returns -EINVAL
> > or zero.
> >
> > Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> >
> > diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
> > index 73d08ed..7b4e294 100644
> > --- a/arch/x86/kernel/cpu/intel_cacheinfo.c
> > +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
> > @@ -466,12 +466,9 @@ static ssize_t store_cache_disable(struct _cpuid4_info *this_leaf,
> > return -EINVAL;
> >
> > err = amd_set_l3_disable_slot(this_leaf->base.nb, cpu, slot, val);
> > - if (err) {
> > - if (err == -EEXIST)
> > - printk(KERN_WARNING "L3 disable slot %d in use!\n",
> > - slot);
> > + if (err)
> > return err;
> > - }
> > +
> > return count;
> > }
> >
>
>
> Looking at the comments around the code and the print statement your patch
> is trying to remove, I wonder if it would be more appropriate to return
> -EEXIST in amd_set_l3_disable_slot(), like this:
>
> ---
> From: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
> Subject: [PATCH] cpu: Fix error return code in amd_set_l3_disable_slot()
>
> If the L3 disable slot is already in use, return -EEXIST instead of -EINVAL.
> The caller, store_cache_disable(), checks this return value to print an
> appropriate warning.
>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
> ---
>
> arch/x86/kernel/cpu/intel_cacheinfo.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
> index 73d08ed..0b49e29 100644
> --- a/arch/x86/kernel/cpu/intel_cacheinfo.c
> +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
> @@ -433,7 +433,7 @@ int amd_set_l3_disable_slot(struct amd_northbridge *nb, int cpu, unsigned slot,
> /* check if @slot is already used or the index is already disabled */
> ret = amd_get_l3_disable_slot(nb, slot);
> if (ret >= 0)
> - return -EINVAL;
> + return -EEXIST;
>
> if (index > nb->l3_cache.indices)
> return -EINVAL;
Well, let's see, there's 8cc1176e5de534d55cb26ff0cef3fd0d6ad8c3c0 which
was intending at looking at -EEXIST when it gets returned but forgot to
return it at the end. Crap. Somebody should b*tchslap its author... oh,
that's me.
Good catch guys, thanks. I'll take a bit enhanced version of Srivatsa's
patch because it goes in the way of what was originally intended. The
enhanced version returns -EEXIST for the other slot too when we're
disabling the same index, see below:
--
From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Date: Thu, 19 Apr 2012 12:35:08 +0200
Subject: [PATCH] x86, intel_cacheinfo: Fix error return code in amd_set_l3_disable_slot()
If the L3 disable slot is already in use, return -EEXIST instead of
-EINVAL. The caller, store_cache_disable(), checks this return value to
print an appropriate warning.
Also, we want to signal with -EEXIST that the current index we're
disabling has actually been already disabled on the node:
$ echo 12 > /sys/devices/system/cpu/cpu3/cache/index3/cache_disable_0
$ echo 12 > /sys/devices/system/cpu/cpu3/cache/index3/cache_disable_0
-bash: echo: write error: File exists
$ echo 12 > /sys/devices/system/cpu/cpu3/cache/index3/cache_disable_1
-bash: echo: write error: File exists
$ echo 12 > /sys/devices/system/cpu/cpu5/cache/index3/cache_disable_1
-bash: echo: write error: File exists
The old code would say
-bash: echo: write error: Invalid argument
for disable slot 1 when playing the example above with no output in
dmesg, which is clearly misleading.
Cc: <stable@...r.kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20120419070053.GB16645@elgon.mountain
[Boris: add testing for the other index too]
Signed-off-by: Borislav Petkov <borislav.petkov@....com>
---
arch/x86/kernel/cpu/intel_cacheinfo.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 73d08ed98a64..b8f3653dddbc 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -433,14 +433,14 @@ int amd_set_l3_disable_slot(struct amd_northbridge *nb, int cpu, unsigned slot,
/* check if @slot is already used or the index is already disabled */
ret = amd_get_l3_disable_slot(nb, slot);
if (ret >= 0)
- return -EINVAL;
+ return -EEXIST;
if (index > nb->l3_cache.indices)
return -EINVAL;
/* check whether the other slot has disabled the same index already */
if (index == amd_get_l3_disable_slot(nb, !slot))
- return -EINVAL;
+ return -EEXIST;
amd_l3_disable_index(nb, cpu, slot, index);
@@ -468,8 +468,8 @@ static ssize_t store_cache_disable(struct _cpuid4_info *this_leaf,
err = amd_set_l3_disable_slot(this_leaf->base.nb, cpu, slot, val);
if (err) {
if (err == -EEXIST)
- printk(KERN_WARNING "L3 disable slot %d in use!\n",
- slot);
+ pr_warning("L3 slot %d in use/index already disabled!\n",
+ slot);
return err;
}
return count;
--
1.7.9.3.362.g71319
--
Regards/Gruss,
Boris.
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists