Message ID | 20180514151332.31352-1-dave@stgolabs.net |
---|---|
State | Rejected, archived |
Delegated to: | David Miller |
Headers | show |
Series | lib/rhashtable: reorder some inititalization sequences | expand |
From: Davidlohr Bueso <dave@stgolabs.net> Date: Mon, 14 May 2018 08:13:32 -0700 > rhashtable_init() allocates memory at the very end of the > call, once everything is setup; with the exception of the > nelems parameter. However, unless the user is doing something > bogus with params for which -EINVAL is returned, memory > allocation is the only operation that can trigger the call > to fail. > > Thus move bucket_table_alloc() up such that we fail back to > the caller asap, instead of doing useless checks. This is > safe as the the table allocation isn't using the halfly > setup 'ht' structure and bucket_table_alloc() call chain only > ends up using the ht->nulls_base member in INIT_RHT_NULLS_HEAD. > > Also move the locking initialization down to the end. > > Signed-off-by: Davidlohr Bueso <dbueso@suse.de> The user potentially "doing something bogus" is why the most expensive part of the initialization (the memory allocation) is done after everything else is validated. I think it's best to keep things as-is.
On Mon, May 14, 2018 at 10:52:13PM -0400, David Miller wrote: > From: Davidlohr Bueso <dave@stgolabs.net> > Date: Mon, 14 May 2018 08:13:32 -0700 > > > rhashtable_init() allocates memory at the very end of the > > call, once everything is setup; with the exception of the > > nelems parameter. However, unless the user is doing something > > bogus with params for which -EINVAL is returned, memory > > allocation is the only operation that can trigger the call > > to fail. > > > > Thus move bucket_table_alloc() up such that we fail back to > > the caller asap, instead of doing useless checks. This is > > safe as the the table allocation isn't using the halfly > > setup 'ht' structure and bucket_table_alloc() call chain only > > ends up using the ht->nulls_base member in INIT_RHT_NULLS_HEAD. > > > > Also move the locking initialization down to the end. > > > > Signed-off-by: Davidlohr Bueso <dbueso@suse.de> > > The user potentially "doing something bogus" is why the most > expensive part of the initialization (the memory allocation) > is done after everything else is validated. > > I think it's best to keep things as-is. I agree. Thanks,
diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 9427b5766134..68aadd6bff60 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -1022,8 +1022,6 @@ int rhashtable_init(struct rhashtable *ht, struct bucket_table *tbl; size_t size; - size = HASH_DEFAULT_SIZE; - if ((!params->key_len && !params->obj_hashfn) || (params->obj_hashfn && !params->obj_cmpfn)) return -EINVAL; @@ -1032,10 +1030,17 @@ int rhashtable_init(struct rhashtable *ht, return -EINVAL; memset(ht, 0, sizeof(*ht)); - mutex_init(&ht->mutex); - spin_lock_init(&ht->lock); memcpy(&ht->p, params, sizeof(*params)); + if (!params->nelem_hint) + size = HASH_DEFAULT_SIZE; + else + size = rounded_hashtable_size(&ht->p); + + tbl = bucket_table_alloc(ht, size, GFP_KERNEL); + if (tbl == NULL) + return -ENOMEM; + if (params->min_size) ht->p.min_size = roundup_pow_of_two(params->min_size); @@ -1050,9 +1055,6 @@ int rhashtable_init(struct rhashtable *ht, ht->p.min_size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE); - if (params->nelem_hint) - size = rounded_hashtable_size(&ht->p); - if (params->locks_mul) ht->p.locks_mul = roundup_pow_of_two(params->locks_mul); else @@ -1068,10 +1070,8 @@ int rhashtable_init(struct rhashtable *ht, } } - tbl = bucket_table_alloc(ht, size, GFP_KERNEL); - if (tbl == NULL) - return -ENOMEM; - + mutex_init(&ht->mutex); + spin_lock_init(&ht->lock); atomic_set(&ht->nelems, 0); RCU_INIT_POINTER(ht->tbl, tbl);
rhashtable_init() allocates memory at the very end of the call, once everything is setup; with the exception of the nelems parameter. However, unless the user is doing something bogus with params for which -EINVAL is returned, memory allocation is the only operation that can trigger the call to fail. Thus move bucket_table_alloc() up such that we fail back to the caller asap, instead of doing useless checks. This is safe as the the table allocation isn't using the halfly setup 'ht' structure and bucket_table_alloc() call chain only ends up using the ht->nulls_base member in INIT_RHT_NULLS_HEAD. Also move the locking initialization down to the end. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> --- lib/rhashtable.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)