Messages in this thread Patch in this message | | | Date | Thu, 6 May 2010 16:13:58 +0200 | From | Borislav Petkov <> | Subject | Re: [113/197] x86, cacheinfo: Calculate L3 indices |
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From: Jiri Kosina <jkosina@suse.cz> Date: Thu, May 06, 2010 at 09:46:21AM -0400
> Well, we have > > #ifdef CONFIG_K8_NB > static inline struct pci_dev *node_to_k8_nb_misc(int node) > { > return (node < num_k8_northbridges) ? k8_northbridges[node] : NULL; > } > #else > static inline struct pci_dev *node_to_k8_nb_misc(int node) > { > return NULL; > } > #endif > > So it legitimately returns NULL in two cases: > > 1) if someone passes too large node > 2) if CONFIG_K8_NB is unset > > 1) Either we assume that node will always be in the range (i.e. > amd_get_nb_id() will never go crazy return anything bogus), and then we > could just drop the test completely. Or we want to check for such the > possibility, and then node_to_k8_nb_misc() is going to return NULL in such > cases, and so we want to check for it.
No, we want to check it since K8_NB has many users - not only L3.
> 2) is now moot, as all three in-tree callers are now under proper ifdefs > (CONFIG_CPU_SUP_AMD, which depends on CONFIG_K8_NB after your patch has > been applied). So I believe we could remove it, right?
I don't think I understand "remove it" here. Which "it" you're referring to?
> Either way, current state seems inconsistent. So either we should add the > return value check to amd_calc_l3_indices() as well, or remove all the > NULL magic altogether, i.e. the (untested) patch below. > > What do you think?
Take a look at
http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-tip.git;a=commitdiff;h=f2b20e41407fccfcfacf927ff91ec888832a37af
This does
+ if (num_k8_northbridges == 0) + return;
in amd_check_l3_disable().
So if K8_NB has failed initializing for some reason, we never go near the pci devs and the node_to_k8_nb_misc() calls since we effectively disable the L3 functionality.
Thus the NULL pointer checks you remove in the patch below are superfluous, I agree, and I have already removed those in my tree along with the other improvements/fixes I'm working on right now.
> > > From: Jiri Kosina <jkosina@suse.cz> > Subject: x86, cacheinfo: remove unnecessary NULL pointer checks > > As K8_NB thing is now always initialized on AMD CPUs, and we don't have > any caller that would be outside CONFIG_CPU_SUP_AMD/CONFIG_K8_NB, it is > safe to assume that kb_northbridges has been always initialized). > > Signed-off-by: Jiri Kosina <jkosina@suse.cz> > > arch/x86/include/asm/k8.h | 10 +--------- > arch/x86/kernel/cpu/intel_cacheinfo.c | 6 ------ > 2 files changed, 1 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/include/asm/k8.h b/arch/x86/include/asm/k8.h > index f70e600..0cff8ba 100644 > --- a/arch/x86/include/asm/k8.h > +++ b/arch/x86/include/asm/k8.h > @@ -15,17 +15,9 @@ extern int k8_get_nodes(struct bootnode *nodes); > extern int k8_numa_init(unsigned long start_pfn, unsigned long end_pfn); > extern int k8_scan_nodes(void); > > -#ifdef CONFIG_K8_NB > static inline struct pci_dev *node_to_k8_nb_misc(int node) > { > - return (node < num_k8_northbridges) ? k8_northbridges[node] : NULL; > + return k8_northbridges[node]; > } > -#else > -static inline struct pci_dev *node_to_k8_nb_misc(int node) > -{ > - return NULL; > -} > -#endif > - > > #endif /* _ASM_X86_K8_H */ > diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c > index b3eeb66..6c5f3cd 100644 > --- a/arch/x86/kernel/cpu/intel_cacheinfo.c > +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c > @@ -355,9 +355,6 @@ static ssize_t show_cache_disable(struct _cpuid4_info *this_leaf, char *buf, > if (!this_leaf->can_disable) > return -EINVAL; > > - if (!dev) > - return -EINVAL; > - > pci_read_config_dword(dev, 0x1BC + index * 4, ®); > return sprintf(buf, "0x%08x\n", reg); > } > @@ -388,9 +385,6 @@ static ssize_t store_cache_disable(struct _cpuid4_info *this_leaf, > if (!capable(CAP_SYS_ADMIN)) > return -EPERM; > > - if (!dev) > - return -EINVAL; > - > if (strict_strtoul(buf, 10, &val) < 0) > return -EINVAL; > > > -- > Jiri Kosina > SUSE Labs, Novell Inc. >
-- Regards/Gruss, Boris.
-- Advanced Micro Devices, Inc. Operating Systems Research Center
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