Messages in this thread | | | Date | Thu, 6 Feb 2020 18:31:53 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v6 6/6] locking/lockdep: Reuse freed chain_hlocks entries |
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On Thu, Feb 06, 2020 at 12:08:20PM -0500, Waiman Long wrote: > On 2/6/20 11:16 AM, Peter Zijlstra wrote: > > On Thu, Feb 06, 2020 at 10:24:08AM -0500, Waiman Long wrote: > >> +static int alloc_chain_hlocks(int req) > >> +{ > >> + int bucket, curr, size; > >> + > >> + /* > >> + * We rely on the MSB to act as an escape bit to denote freelist > >> + * pointers. Make sure this bit isn't set in 'normal' class_idx usage. > >> + */ > >> + BUILD_BUG_ON((MAX_LOCKDEP_KEYS-1) & CHAIN_BLK_FLAG); > >> + > >> + init_data_structures_once(); > >> + > >> + if (nr_free_chain_hlocks < req) > >> + return -1; > >> + > >> + /* > >> + * We require a minimum of 2 (u16) entries to encode a freelist > >> + * 'pointer'. > >> + */ > >> + req = max(req, 2); > >> + bucket = size_to_bucket(req); > >> + curr = chain_block_buckets[bucket]; > >> + > >> + if (bucket && (curr >= 0)) { > >> + del_chain_block(bucket, req, chain_block_next(curr)); > >> + return curr; > >> + } else if (bucket) { > >> + /* Try bucket 0 */ > >> + curr = chain_block_buckets[0]; > >> + } > > if (bucket) { > > if (curr >= 0) { > > del_chain_block(bucket, req, chain_block_next(curr)); > > return curr; > > } > > /* Try bucket 0 */ > > curr = chain_block_bucket[0]; > > } > > > > reads much easier IMO. > > Yes, that is simpler. I can send out an updated patch if you want, or > you can apply the change when you pull the patch.
I'll frob it. Thanks!
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