Re: [PATCH RFC 2/6] rhashtable: Call library function alloc_bucket_locks

[Herbert Xu]

Tom Herbert  wrote:
> To allocate the array of bucket locks for the hash table we now
> call library function alloc_bucket_spinlocks. This function is
> based on the old alloc_bucket_locks in rhashtable and should
> produce the same effect.
> 
> Signed-off-by: Tom Herbert 

This conflicts with the work I'm doing to fix the resize ENOMEM
issue.  I'll be making the hashtable as well as the spinlock table
nested, in which case you must not directly dereference it as an
array.

If you're just trying to share the spinlocks for another purpose,
what we can do is provide a helper function to return the right
lock for a given key/object.

Cheers,
-- 
Email: Herbert Xu 
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH RFC 2/6] rhashtable: Call library function alloc_bucket_locks

[Thomas Graf]

On 09/09/16 at 04:19pm, Tom Herbert wrote:
> To allocate the array of bucket locks for the hash table we now
> call library function alloc_bucket_spinlocks. This function is
> based on the old alloc_bucket_locks in rhashtable and should
> produce the same effect.
> 
> Signed-off-by: Tom Herbert 

Acked-by: Thomas Graf 

[PATCH RFC 2/6] rhashtable: Call library function alloc_bucket_locks

[Tom Herbert]

To allocate the array of bucket locks for the hash table we now
call library function alloc_bucket_spinlocks. This function is
based on the old alloc_bucket_locks in rhashtable and should
produce the same effect.

Signed-off-by: Tom Herbert 
---
 lib/rhashtable.c | 46 --
 1 file changed, 4 insertions(+), 42 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 06c2872..5b53304 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -59,50 +59,10 @@ EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held);
 #define ASSERT_RHT_MUTEX(HT)
 #endif
 
-
-static int alloc_bucket_locks(struct rhashtable *ht, struct bucket_table *tbl,
- gfp_t gfp)
-{
-   unsigned int i, size;
-#if defined(CONFIG_PROVE_LOCKING)
-   unsigned int nr_pcpus = 2;
-#else
-   unsigned int nr_pcpus = num_possible_cpus();
-#endif
-
-   nr_pcpus = min_t(unsigned int, nr_pcpus, 64UL);
-   size = roundup_pow_of_two(nr_pcpus * ht->p.locks_mul);
-
-   /* Never allocate more than 0.5 locks per bucket */
-   size = min_t(unsigned int, size, tbl->size >> 1);
-
-   if (sizeof(spinlock_t) != 0) {
-   tbl->locks = NULL;
-#ifdef CONFIG_NUMA
-   if (size * sizeof(spinlock_t) > PAGE_SIZE &&
-   gfp == GFP_KERNEL)
-   tbl->locks = vmalloc(size * sizeof(spinlock_t));
-#endif
-   if (gfp != GFP_KERNEL)
-   gfp |= __GFP_NOWARN | __GFP_NORETRY;
-
-   if (!tbl->locks)
-   tbl->locks = kmalloc_array(size, sizeof(spinlock_t),
-  gfp);
-   if (!tbl->locks)
-   return -ENOMEM;
-   for (i = 0; i < size; i++)
-   spin_lock_init(>locks[i]);
-   }
-   tbl->locks_mask = size - 1;
-
-   return 0;
-}
-
 static void bucket_table_free(const struct bucket_table *tbl)
 {
if (tbl)
-   kvfree(tbl->locks);
+   free_bucket_spinlocks(tbl->locks);
 
kvfree(tbl);
 }
@@ -131,7 +91,9 @@ static struct bucket_table *bucket_table_alloc(struct 
rhashtable *ht,
 
tbl->size = nbuckets;
 
-   if (alloc_bucket_locks(ht, tbl, gfp) < 0) {
+   /* Never allocate more than 0.5 locks per bucket */
+   if (alloc_bucket_spinlocks(>locks, >locks_mask,
+  tbl->size >> 1, ht->p.locks_mul, gfp)) {
bucket_table_free(tbl);
return NULL;
}
-- 
2.8.0.rc2