Messages in this thread | | | Date | Thu, 30 Aug 2018 23:03:52 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH v2 1/3] RISC-V: Add logical CPU indexing for RISC-V |
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On Tue, Aug 28, 2018 at 01:36:08AM -0700, Atish Patra wrote: > Currently, both linux cpu id and hardware cpu id are same. > This is not recommended as it will lead to discontinuous cpu > indexing in Linux. Moreover, kdump kernel will run from CPU0 > which would be absent if we follow existing scheme. > > Implement a logical mapping between Linux cpu id and hardware > cpuid to decouple these two. Always mark the boot processor as > cpu0 and all other cpus get the logical cpu id based on their > booting order. > > Signed-off-by: Atish Patra <atish.patra@wdc.com> > --- > arch/riscv/include/asm/smp.h | 18 +++++++++++++++++- > arch/riscv/kernel/setup.c | 2 ++ > arch/riscv/kernel/smp.c | 19 +++++++++++++++++++ > 3 files changed, 38 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h > index 36016845..a5c257b3 100644 > --- a/arch/riscv/include/asm/smp.h > +++ b/arch/riscv/include/asm/smp.h > @@ -22,6 +22,13 @@ > #include <linux/cpumask.h> > #include <linux/irqreturn.h> > > +#define INVALID_HARTID -1 > +/* > + * Mapping between linux logical cpu index and hartid. > + */ > +extern unsigned long __cpu_logical_map[NR_CPUS]; > +#define cpu_logical_map(cpu) __cpu_logical_map[cpu]
How about naming this cpuid_to_hardid_map to make things a little more obvious? Also shouldn't this be signed given your INVALID_HARTID definition above.
> +static inline int riscv_hartid_to_cpuid(int hartid) { return 0 ; } > +static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in, > + struct cpumask *out) { > + cpumask_set_cpu(cpu_logical_map(0), out); > +}
Please use normal coding style even for stubs:
static inline int riscv_hartid_to_cpuid(int hartid) { return 0; }
static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out) { cpumask_set_cpu(cpu_logical_map(0), out); }
> +unsigned long __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HARTID };
Please break the line into the usual format:
unsigned long __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HARTID, };
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