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 <[email protected]>
---
lib/rhashtable.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
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);
--
2.13.6
From: Davidlohr Bueso <[email protected]>
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 <[email protected]>
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 <[email protected]>
> 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 <[email protected]>
>
> 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,
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt