Messages in this thread | | | From | NeilBrown <> | Date | Wed, 27 Mar 2019 09:40:14 +1100 | Subject | Re: [PATCH 3/4] rhashtable: use bit_spin_locks to protect hash bucket. |
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On Tue, Mar 26 2019, Herbert Xu wrote:
> On Mon, Mar 25, 2019 at 04:05:39PM +1100, NeilBrown wrote: >> >> +/* >> + * If 'p' is a bucket head and might be locked: >> + * rht_ptr() returns the address without the lock bit. >> + * rht_ptr_locked() returns the address WITH the lock bit. >> + * rht_is_locked() tests if the lock bit is set. >> + */ >> +static inline struct rhash_head __rcu *rht_ptr(const struct rhash_head *p) >> +{ >> + return (void *)(((unsigned long)p) & ~2UL); >> +} > > My preference would be to turn rhash_head * into an opaque type > that can only be dereferenced through rht_ptr.
I can try that. Presumably the 'next' pointer in 'struct rhash_head' can still be a normal pointer, but the buckets in the bucket_table would need to opaque pointers. Maybe pointers to some new undefined struct, which gets cast and masked as appropriate?
I'll have a go and see how it looks.
Thanks, NeilBrown [unhandled content-type:application/pgp-signature] | |