On 12/13/19 9:45 PM, Josh Poimboeuf wrote:
> On Fri, Dec 13, 2019 at 04:04:58PM -0800, Randy Dunlap wrote:
>>> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
>>> index b2e8fd8a8e59..bbd68520f5f1 100644
>>> --- a/fs/btrfs/ctree.h
>>> +++ b/fs/btrfs/ctree.h
>>> @@ -3110,14 +3110,16 @@ do {								\
>>>  	rcu_read_unlock();					\
>>>  } while (0)
>>>  
>>> -__cold
>>> +#ifdef CONFIG_BTRFS_ASSERT
>>> +__cold __unlikely
>>
>> what provides __unlikely?  It is causing build errors.
>>
>> and if I remove the "__unlikely", I still see the objtool warnings
>> (unreachable instructions).
> 
> Ha, not sure how that happened... Should be __noreturn instead of
> __unlikely.  Cheers...
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index b2e8fd8a8e59..398bd010dfc5 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -3110,14 +3110,16 @@ do {								\
>  	rcu_read_unlock();					\
>  } while (0)
>  
> -__cold
> +#ifdef CONFIG_BTRFS_ASSERT
> +__cold __noreturn
>  static inline void assfail(const char *expr, const char *file, int line)
>  {
> -	if (IS_ENABLED(CONFIG_BTRFS_ASSERT)) {
> -		pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
> -		BUG();
> -	}
> +	pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
> +	BUG();
>  }
> +#else
> +static inline void assfail(const char *expr, const char *file, int line) {}
> +#endif
>  
>  #define ASSERT(expr)	\
>  	(likely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
> 

OK, that fixes most of them, but still leaves these 2:

btrfs006.out:fs/btrfs/extent_io.o: warning: objtool: __set_extent_bit()+0x536: unreachable instruction
btrfs006.out:fs/btrfs/relocation.o: warning: objtool: add_tree_block()+0x501: unreachable instruction

Those .o files are attached.

-- 
~Randy