On Thu, 8 Sep 2016, Fenghua Yu wrote:
> @@ -0,0 +1,12 @@
> +#ifndef _RDT_H_
> +#define _RDT_H_
The standard guard is
_ASM_X86_RDT_H
> +
> +#ifdef CONFIG_INTEL_RDT
What's the purpose of sticking a struct definition inside an ifdef?
> +
> +struct clos_cbm_table {
> + unsigned long cbm;
> + unsigned int clos_refcnt;
Please proper align the struct members for readability sake
unsigned long cbm;
unsigned int clos_refcnt;
Adding a kerneldoc comment above the struct explaining it would not hurting
either.
> +/*
> + * cctable maintains 1:1 mapping between CLOSid and cache bitmask.
> + */
> +static struct clos_cbm_table *cctable;
> +/*
> + * closid availability bit map.
> + */
> +unsigned long *closmap;
> +static DEFINE_MUTEX(rdtgroup_mutex);
> +
> +static inline void closid_get(u32 closid)
> +{
> + struct clos_cbm_table *cct = &cctable[closid];
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + cct->clos_refcnt++;
So the whole thing can be written with a single line at the single call
site.
cc_table[closid].clos_refcnt++;
And that already has the lockdep_assert_held() check. While companies might
pay based on line counts, kernel development asks for readable and sensible
code.
> +}
> +
> +static int closid_alloc(u32 *closid)
> +{
> + u32 maxid;
> + u32 id;
Please put variables with the same type into one line. There is no value in
wasting screen estate.
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + maxid = boot_cpu_data.x86_cache_max_closid;
> + id = find_first_zero_bit(closmap, maxid);
> + if (id == maxid)
> + return -ENOSPC;
> +
> + set_bit(id, closmap);
> + closid_get(id);
> + *closid = id;
> +
> + return 0;
> +}
> +
> +static inline void closid_free(u32 closid)
> +{
> + clear_bit(closid, closmap);
> + cctable[closid].cbm = 0;
> +}
> +
> +static void closid_put(u32 closid)
> +{
> + struct clos_cbm_table *cct = &cctable[closid];
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> + if (WARN_ON(!cct->clos_refcnt))
> + return;
> +
> + if (!--cct->clos_refcnt)
> + closid_free(closid);
> +}
>
> static int __init intel_rdt_late_init(void)
> {
> struct cpuinfo_x86 *c = &boot_cpu_data;
> + u32 maxid;
> + int err = 0, size;
>
> if (!cpu_has(c, X86_FEATURE_CAT_L3))
> return -ENODEV;
>
> - pr_info("Intel cache allocation detected\n");
> + maxid = c->x86_cache_max_closid;
>
> - return 0;
> + size = maxid * sizeof(struct clos_cbm_table);
> + cctable = kzalloc(size, GFP_KERNEL);
> + if (!cctable) {
> + err = -ENOMEM;
> + goto out_err;
I told you that before: Using a goto just to return err is pointless and
silly. What the hell is wrong with
return -ENOMEM;
???
> + }
> +
> + size = BITS_TO_LONGS(maxid) * sizeof(long);
> + closmap = kzalloc(size, GFP_KERNEL);
> + if (!closmap) {
> + kfree(cctable);
> + err = -ENOMEM;
> + goto out_err;
Groan.
> + }
> +
> + pr_info("Intel cache allocation enabled\n");
> +out_err:
