diff mbox

[5/6] rhashtable: Add rehash counter to bucket_table

Message ID E1YWMLC-0000CE-RS@gondolin.me.apana.org.au
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Herbert Xu March 13, 2015, 9:57 a.m. UTC
This patch adds a rehash counter to bucket_table to indicate
the last bucket that has been rehashed.  This serves two purposes:

1. Any bucket that has been rehashed can never gain a new object.
2. If the rehash counter reaches the size of the table, the table
will forever remain empty.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

 include/linux/rhashtable.h |    4 +++-
 lib/rhashtable.c           |    1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

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Comments

Thomas Graf March 13, 2015, 1:51 p.m. UTC | #1
On 03/13/15 at 08:57pm, Herbert Xu wrote:
> @@ -58,7 +59,8 @@ struct rhash_head {
>   * @buckets: size * hash buckets
>   */
>  struct bucket_table {
> -	size_t			size;
> +	unsigned int		size;
> +	unsigned int		rehash;
>  	u32			hash_rnd;
>  	u32			shift;
>  	unsigned int		locks_mask;

This changes causes a minor warning:
lib/test_rhashtable.c: In function ‘test_bucket_stats’:
lib/test_rhashtable.c:83:4: warning: format ‘%zu’ expects argument of
type ‘size_t’, but argument 3 has type ‘unsigned int’ [-Wformat=]
    pr_info(" [%#4x/%zu]", i, tbl->size)
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Herbert Xu March 14, 2015, 2:49 a.m. UTC | #2
On Fri, Mar 13, 2015 at 01:51:31PM +0000, Thomas Graf wrote:
> On 03/13/15 at 08:57pm, Herbert Xu wrote:
> > @@ -58,7 +59,8 @@ struct rhash_head {
> >   * @buckets: size * hash buckets
> >   */
> >  struct bucket_table {
> > -	size_t			size;
> > +	unsigned int		size;
> > +	unsigned int		rehash;
> >  	u32			hash_rnd;
> >  	u32			shift;
> >  	unsigned int		locks_mask;
> 
> This changes causes a minor warning:
> lib/test_rhashtable.c: In function ‘test_bucket_stats’:
> lib/test_rhashtable.c:83:4: warning: format ‘%zu’ expects argument of
> type ‘size_t’, but argument 3 has type ‘unsigned int’ [-Wformat=]
>     pr_info(" [%#4x/%zu]", i, tbl->size)

Thanks.  I have now enabled test_rhashtable in my config so I
should be able to catch it next time.
diff mbox

Patch

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index a0abddd..ed7562a 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -49,6 +49,7 @@  struct rhash_head {
 /**
  * struct bucket_table - Table of hash buckets
  * @size: Number of hash buckets
+ * @rehash: Current bucket being rehashed
  * @hash_rnd: Random seed to fold into hash
  * @shift: Current size (1 << shift)
  * @locks_mask: Mask to apply before accessing locks[]
@@ -58,7 +59,8 @@  struct rhash_head {
  * @buckets: size * hash buckets
  */
 struct bucket_table {
-	size_t			size;
+	unsigned int		size;
+	unsigned int		rehash;
 	u32			hash_rnd;
 	u32			shift;
 	unsigned int		locks_mask;
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 36fb091..ff4ea17 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -260,6 +260,7 @@  static void rhashtable_rehash_chain(struct rhashtable *ht, unsigned old_hash)
 	spin_lock_bh(old_bucket_lock);
 	while (!rhashtable_rehash_one(ht, old_hash))
 		;
+	old_tbl->rehash++;
 	spin_unlock_bh(old_bucket_lock);
 }