Re: [XEN PATCH v3] xen/sched: mechanical renaming to address MISRA C:2012 Rule 5.3

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 28 Jul 2023, Nicola Vetrini wrote:
> Rule 5.3 has the following headline:
> "An identifier declared in an inner scope shall not hide an
> identifier declared in an outer scope"
> 
> The renaming s/sched_id/scheduler_id/ of the function defined in
> 'xen/common/sched/core.c' prevents any hiding of that function
> by the instances of homonymous function parameters that
> are defined in inner scopes.
> 
> Similarly, the renames
> - s/ops/operations/ for the static variable in 'xen/common/sched/core.c'
> - s/do_softirq/needs_softirq/
> are introduced for variables, to avoid any conflict with homonymous
> parameters or function identifiers.
> 
> Moreover, the variable 'loop' defined at 'xen/common/sched/credit2.c:3887'
> has been dropped, in favour of the homonymous variable declared in the
> outer scope. This in turn requires a modification of the printk call that
> involves it.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes in v3:
> - removed stray changes to address the remarks
> Changes in v2:
> - s/softirq/needs_softirq/
> - Dropped local variable 'it'
> - Renamed the 'ops' static variable instead of function parameters
> in the idle scheduler for coherence.
> 
> Note: local variable 'j' in xen/common/sched/credit2.c:3812' should
> probably be unsigned as well, but I saw while editing the patch
> that it's used as a parameter to 'dump_pcpu', which takes an int.
> Possibly changing the types of parameters used in these calls is
> probably a good target for another patch, as it's not relevant
> w.r.t. Rule 5.3.
> ---
>  xen/common/sched/core.c    | 28 ++++++++++++++--------------
>  xen/common/sched/credit2.c |  6 +++---
>  xen/common/sysctl.c        |  2 +-
>  xen/include/xen/sched.h    |  2 +-
>  4 files changed, 19 insertions(+), 19 deletions(-)
> 
> diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c
> index 022f548652..12deefa745 100644
> --- a/xen/common/sched/core.c
> +++ b/xen/common/sched/core.c
> @@ -91,7 +91,7 @@ extern const struct scheduler *__start_schedulers_array[], 
> *__end_schedulers_arr
>  #define NUM_SCHEDULERS (__end_schedulers_array - __start_schedulers_array)
>  #define schedulers __start_schedulers_array
> 
> -static struct scheduler __read_mostly ops;
> +static struct scheduler __read_mostly operations;
> 
>  static bool scheduler_active;
> 
> @@ -171,7 +171,7 @@ static inline struct scheduler *dom_scheduler(const 
> struct domain *d)
>       * is the default scheduler that has been, choosen at boot.
>       */
>      ASSERT(is_idle_domain(d));
> -    return &ops;
> +    return &operations;
>  }
> 
>  static inline struct scheduler *unit_scheduler(const struct sched_unit *unit)
> @@ -2040,10 +2040,10 @@ long do_set_timer_op(s_time_t timeout)
>      return 0;
>  }
> 
> -/* sched_id - fetch ID of current scheduler */
> -int sched_id(void)
> +/* scheduler_id - fetch ID of current scheduler */
> +int scheduler_id(void)
>  {
> -    return ops.sched_id;
> +    return operations.sched_id;
>  }
> 
>  /* Adjust scheduling parameter for a given domain. */
> @@ -2579,7 +2579,7 @@ static void cf_check sched_slave(void)
>      struct sched_unit    *prev = vprev->sched_unit, *next;
>      s_time_t              now;
>      spinlock_t           *lock;
> -    bool                  do_softirq = false;
> +    bool                  needs_softirq = false;
>      unsigned int          cpu = smp_processor_id();
> 
>      ASSERT_NOT_IN_ATOMIC();
> @@ -2604,7 +2604,7 @@ static void cf_check sched_slave(void)
>              return;
>          }
> 
> -        do_softirq = true;
> +        needs_softirq = true;
>      }
> 
>      if ( !prev->rendezvous_in_cnt )
> @@ -2614,7 +2614,7 @@ static void cf_check sched_slave(void)
>          rcu_read_unlock(&sched_res_rculock);
> 
>          /* Check for failed forced context switch. */
> -        if ( do_softirq )
> +        if ( needs_softirq )
>              raise_softirq(SCHEDULE_SOFTIRQ);
> 
>          return;
> @@ -3016,14 +3016,14 @@ void __init scheduler_init(void)
>          BUG_ON(!scheduler);
>          printk("Using '%s' (%s)\n", scheduler->name, scheduler->opt_name);
>      }
> -    ops = *scheduler;
> +    operations = *scheduler;
> 
>      if ( cpu_schedule_up(0) )
>          BUG();
>      register_cpu_notifier(&cpu_schedule_nfb);
> 
> -    printk("Using scheduler: %s (%s)\n", ops.name, ops.opt_name);
> -    if ( sched_init(&ops) )
> +    printk("Using scheduler: %s (%s)\n", operations.name, 
> operations.opt_name);
> +    if ( sched_init(&operations) )
>          panic("scheduler returned error on init\n");
> 
>      if ( sched_ratelimit_us &&
> @@ -3363,7 +3363,7 @@ int schedule_cpu_rm(unsigned int cpu, struct 
> cpu_rm_data *data)
> 
>  struct scheduler *scheduler_get_default(void)
>  {
> -    return &ops;
> +    return &operations;
>  }
> 
>  struct scheduler *scheduler_alloc(unsigned int sched_id)
> @@ -3392,7 +3392,7 @@ struct scheduler *scheduler_alloc(unsigned int sched_id)
> 
>  void scheduler_free(struct scheduler *sched)
>  {
> -    BUG_ON(sched == &ops);
> +    BUG_ON(sched == &operations);
>      sched_deinit(sched);
>      xfree(sched);
>  }
> @@ -3416,7 +3416,7 @@ void schedule_dump(struct cpupool *c)
>      }
>      else
>      {
> -        sched = &ops;
> +        sched = &operations;
>          cpus = &cpupool_free_cpus;
>      }
> 
> diff --git a/xen/common/sched/credit2.c b/xen/common/sched/credit2.c
> index 87a1e31ee9..fc583915df 100644
> --- a/xen/common/sched/credit2.c
> +++ b/xen/common/sched/credit2.c
> @@ -3874,7 +3874,7 @@ csched2_dump(const struct scheduler *ops)
> 
>              lock = unit_schedule_lock(unit);
> 
> -            printk("\t%3d: ", ++loop);
> +            printk("\t%3u: ", ++loop);
>              csched2_dump_unit(prv, svc);
> 
>              unit_schedule_unlock(lock, unit);
> @@ -3884,8 +3884,8 @@ csched2_dump(const struct scheduler *ops)
>      list_for_each_entry ( rqd, &prv->rql, rql )
>      {
>          struct list_head *iter, *runq = &rqd->runq;
> -        int loop = 0;
> 
> +        loop = 0;
>          /* We need the lock to scan the runqueue. */
>          spin_lock(&rqd->lock);
> 
> @@ -3901,7 +3901,7 @@ csched2_dump(const struct scheduler *ops)
> 
>              if ( svc )
>              {
> -                printk("\t%3d: ", loop++);
> +                printk("\t%3u: ", loop++);
>                  csched2_dump_unit(prv, svc);
>              }
>          }
> diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
> index 0cbfe8bd44..7cabfb0230 100644
> --- a/xen/common/sysctl.c
> +++ b/xen/common/sysctl.c
> @@ -71,7 +71,7 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) 
> u_sysctl)
>          break;
> 
>      case XEN_SYSCTL_sched_id:
> -        op->u.sched_id.sched_id = sched_id();
> +        op->u.sched_id.sched_id = scheduler_id();
>          break;
> 
>      case XEN_SYSCTL_getdomaininfolist:
> diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
> index 854f3e32c0..bfe714d2e2 100644
> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -791,7 +791,7 @@ int  sched_init_domain(struct domain *d, unsigned int 
> poolid);
>  void sched_destroy_domain(struct domain *d);
>  long sched_adjust(struct domain *, struct xen_domctl_scheduler_op *);
>  long sched_adjust_global(struct xen_sysctl_scheduler_op *);
> -int  sched_id(void);
> +int  scheduler_id(void);
> 
>  /*
>   * sched_get_id_by_name - retrieves a scheduler id given a scheduler name
> --
> 2.34.1
>