Re: [PATCH v2 02/15] slab: add struct kmem_cache_args

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 9/4/24 18:16, Mike Rapoport wrote:
> On Wed, Sep 04, 2024 at 05:49:15PM +0200, Vlastimil Babka wrote:
>> On 9/4/24 17:16, Mike Rapoport wrote:
>> > On Tue, Sep 03, 2024 at 04:20:43PM +0200, Christian Brauner wrote:
>> >> @@ -275,7 +285,7 @@ do_kmem_cache_create_usercopy(const char *name,
>> >>  
>> >>  	mutex_lock(&slab_mutex);
>> >>  
>> >> -	err = kmem_cache_sanity_check(name, size);
>> >> +	err = kmem_cache_sanity_check(name, object_size);
>> >>  	if (err) {
>> >>  		goto out_unlock;
>> >>  	}
>> >> @@ -296,12 +306,14 @@ do_kmem_cache_create_usercopy(const char *name,
>> >>  
>> >>  	/* Fail closed on bad usersize of useroffset values. */
>> >>  	if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) ||
>> >> -	    WARN_ON(!usersize && useroffset) ||
>> >> -	    WARN_ON(size < usersize || size - usersize < useroffset))
>> >> -		usersize = useroffset = 0;
>> >> -
>> >> -	if (!usersize)
>> >> -		s = __kmem_cache_alias(name, size, align, flags, ctor);
>> >> +	    WARN_ON(!args->usersize && args->useroffset) ||
>> >> +	    WARN_ON(object_size < args->usersize ||
>> >> +		    object_size - args->usersize < args->useroffset))
>> >> +		args->usersize = args->useroffset = 0;
>> >> +
>> >> +	if (!args->usersize)
>> >> +		s = __kmem_cache_alias(name, object_size, args->align, flags,
>> >> +				       args->ctor);
>> > 
>> > Sorry I missed it in the previous review, but nothing guaranties that
>> > nobody will call kmem_cache_create_args with args != NULL.
>> > 
>> > I think there should be a check for args != NULL and a substitution of args
>> > with defaults if it actually was NULL.
>> 
>> Hm there might be a bigger problem with this? If we wanted to do a
>> (non-flag-day) conversion to the new kmem_cache_create() for some callers
>> that need none of the extra args, passing NULL wouldn't work for the
>> _Generic((__args) looking for "struct kmem_cache_args *" as NULL is not of
>> that type, right?
>> 
>> I tried and it really errors out.
> 
> How about
> 
> #define kmem_cache_create(__name, __object_size, __args, ...)           \
> 	_Generic((__args),                                              \
> 		struct kmem_cache_args *: __kmem_cache_create_args,	\
> 		void *: __kmem_cache_create_args,			\
> 		default: __kmem_cache_create)(__name, __object_size, __args, __VA_ARGS__)

Seems to work. I'd agree with the "if NULL, use a static default" direction
then. It just seems like a more user-friendly API to me.





[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux