How to fix warning 'control reaches end of non-void function'

Hi

What is it a right way to fix these warnings?

smth function()

{
       switch (var) {
       case one:
               return 1;
       default:
               BUG();
       }
}

warning: control reaches end of non-void function

Thanks!

--
To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ

Hi

What is it a right way to fix these warnings?

smth function()

{
	switch (var) {
	case one:
		return 1;
	default:
		BUG();
	}
}

warning: control reaches end of non-void function

Hi

What is it a right way to fix these warnings?

smth function()

{
	switch (var) {
	case one:
		return 1;
	default:
		BUG();
	}
}

warning: control reaches end of non-void function

Quoted 14 lines · Alexander Beregalov

Hi

What is it a right way to fix these warnings?

smth function()

{
	switch (var) {
	case one:
		return 1;
	default:
		BUG();
	}
}

Quoted 1 line

warning: control reaches end of non-void function

If BUG() would be normal function it could be marked as __attribute__((noreturn)). But it's a macro defined differently depending on architecture and CONFIG_*. Sometimes it calls panic() which is annotated properly and sometimes it calls other code....

If you are brave, you could fix all implementations.

What is it a right way to fix these warnings?

smth function()

{
	switch (var) {
	case one:
		return 1;
	default:
		BUG();
	}
}

warning: control reaches end of non-void function

Quoted 12 lines · Alexander Beregalov

What is it a right way to fix these warnings?

smth function()

{
       switch (var) {
       case one:
               return 1;
       default:
               BUG();
       }
}

Quoted 1 line

warning: control reaches end of non-void function

BUG() may actually do nothing so I'd just reorder things around as

int function(void)

{
       switch (var) {
       case 1:
               break;
       default:
               BUG();
       }
       return 1;
}

Rene.
--
To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

If we haven't beat this to death yet, the right way to fix these warnings is to return a "smth" data type... which most people have commented on

// original version
smth function()

{
      switch (var) {
      case one:
              return 1;
      default:
              BUG();
      }
}

// modified version
smth function()
{
smth ret = 0;
switch (var) { // unless this is a global var is undefined
case one:
ret = 1; // 1 was not a 'smth' type so we should use
the function's return type or face compiler errors/warnings
break; // unless you want hard to find bugs always

include a break;
      default:
              BUG(); // if this is a macro does it return a value?
              ret = 0;
              break;
      }
      return ret;  // since we are returning a 'smth' type we do not

let control reach the end of this non-void funtion }

Where does this function get used, and what is it used for?

2008/7/30 Jacob <[email protected]>:

Quoted 30 lines

If we haven't beat this to death yet, the right way to fix these warnings is to return a "smth" data type... which most people have commented on

// original version
smth function()

{
      switch (var) {
      case one:
              return 1;
      default:
              BUG();
      }
}

// modified version
smth function()
{
smth ret = 0;
switch (var) { // unless this is a global var is undefined
case one:
ret = 1; // 1 was not a 'smth' type so we should use
the function's return type or face compiler errors/warnings
break; // unless you want hard to find bugs always

include a break;
      default:
              BUG(); // if this is a macro does it return a value?
              ret = 0;
              break;
      }
      return ret;  // since we are returning a 'smth' type we do not

Quoted 2 lines

let control reach the end of this non-void funtion }

Looks good, but how can I know which value should it return in that case?

Quoted 1 line

Quoted 2 lines

Where does this function get used, and what is it used for?

Ok, some examples

kernel/cpuset.c:

static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)

{
       struct cpuset *cs = cgroup_cs(cont);
       cpuset_filetype_t type = cft->private;
       switch (type) {
       case FILE_CPU_EXCLUSIVE:
               return is_cpu_exclusive(cs);
       case FILE_MEM_EXCLUSIVE:
               return is_mem_exclusive(cs);
       case FILE_MEM_HARDWALL:
               return is_mem_hardwall(cs);
       case FILE_SCHED_LOAD_BALANCE:
               return is_sched_load_balance(cs);
       case FILE_MEMORY_MIGRATE:
               return is_memory_migrate(cs);
       case FILE_MEMORY_PRESSURE_ENABLED:
               return cpuset_memory_pressure_enabled;
       case FILE_MEMORY_PRESSURE:
               return fmeter_getrate(&cs->fmeter);
       case FILE_SPREAD_PAGE:
               return is_spread_page(cs);
       case FILE_SPREAD_SLAB:
               return is_spread_slab(cs);
       default:
               BUG();
       }
}

static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)

{
       struct cpuset *cs = cgroup_cs(cont);
       cpuset_filetype_t type = cft->private;
       switch (type) {
       case FILE_SCHED_RELAX_DOMAIN_LEVEL:
               return cs->relax_domain_level;
       default:
               BUG();
       }
}

mm/mempolicy.c:

/*
* Depending on the memory policy provide a node from which to allocate the
* next slab entry.
* @policy must be protected by freeing by the caller. If @policy is
* the current task's mempolicy, this protection is implicit, as only the
* task can change it's policy. The system default policy requires no
* such protection.
*/
unsigned slab_node(struct mempolicy *policy)

{
       if (!policy || policy->flags & MPOL_F_LOCAL)
               return numa_node_id();

       switch (policy->mode) {
       case MPOL_PREFERRED:
               /*
                * handled MPOL_F_LOCAL above
                */
               return policy->v.preferred_node;

       case MPOL_INTERLEAVE:
               return interleave_nodes(policy);

       case MPOL_BIND: {
               /*
                * Follow bind policy behavior and start allocation at the
                * first node.
                */
               struct zonelist *zonelist;
               struct zone *zone;
               enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
               zonelist = &NODE_DATA(numa_node_id())->node_zonelists[0];
               (void)first_zones_zonelist(zonelist, highest_zoneidx,
                                                       &policy->v.nodes,
                                                       &zone);
               return zone->node;
       }

       default:
               BUG();
       }
}

drivers/net/sky2.c:

/* Chip internal frequency for clock calculations */ static u32 sky2_mhz(const struct sky2_hw *hw)

{
       switch (hw->chip_id) {
       case CHIP_ID_YUKON_EC:
       case CHIP_ID_YUKON_EC_U:
       case CHIP_ID_YUKON_EX:
       case CHIP_ID_YUKON_SUPR:
       case CHIP_ID_YUKON_UL_2:
               return 125;

       case CHIP_ID_YUKON_FE:
               return 100;

       case CHIP_ID_YUKON_FE_P:
               return 50;

       case CHIP_ID_YUKON_XL:
               return 156;

       default:
               BUG();
       }
}

--
To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ

Looks good, but how can I know which value should it return in that case?

Quoted 2 lines · Alexander Beregalov

Looks good, but how can I know which value should it return in that case?

I think you should specify an error code to return, letting the caller decide what to do with it.