Re: [Xen-devel] [PATCH 06/16] tmem: cleanup: reorg do_tmem_put()

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Nov 20, 2013 at 04:46:15PM +0800, Bob Liu wrote:
> Reorg code logic of do_tmem_put() to make it more readable and also drop 
> useless
> local parameters.
> 
> Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
> ---
>  xen/common/tmem.c |   87 
> ++++++++++++++++++++++++++++++-----------------------
>  1 file changed, 49 insertions(+), 38 deletions(-)
> 
> diff --git a/xen/common/tmem.c b/xen/common/tmem.c
> index de3559d..1c9dd5a 100644
> --- a/xen/common/tmem.c
> +++ b/xen/common/tmem.c
> @@ -1509,50 +1509,56 @@ static int do_tmem_put(struct tmem_pool *pool,
>                struct oid *oidp, uint32_t index,
>                xen_pfn_t cmfn, tmem_cli_va_param_t clibuf)
>  {
> -    struct tmem_object_root *obj = NULL, *objfound = NULL, *objnew = NULL;
> -    struct tmem_page_descriptor *pgp = NULL, *pgpdel = NULL;
> -    struct client *client = pool->client;
> -    int ret = client->frozen ? -EFROZEN : -ENOMEM;
> +    struct tmem_object_root *obj = NULL;
> +    struct tmem_page_descriptor *pgp = NULL;
> +    struct client *client;
> +    int ret, newobj = 0;
>  
>      ASSERT(pool != NULL);
> +    client = pool->client;
> +    ret = client->frozen ? -EFROZEN : -ENOMEM;
>      pool->puts++;
>      /* does page already exist (dup)?  if so, handle specially */
> -    if ( (obj = objfound = obj_find(pool,oidp)) != NULL )
> +    if ( (obj = obj_find(pool,oidp)) != NULL )
>      {
> -        ASSERT_SPINLOCK(&objfound->obj_spinlock);
> -        if ((pgp = pgp_lookup_in_obj(objfound, index)) != NULL)
> +        if ((pgp = pgp_lookup_in_obj(obj, index)) != NULL)
> +        {
>              return do_tmem_dup_put(pgp, cmfn, clibuf);
> +        }
> +        else
> +        {
> +            /* no puts allowed into a frozen pool (except dup puts) */
> +            if ( client->frozen )
> +             goto unlock_obj;
> +        }
>      }
> -
> -    /* no puts allowed into a frozen pool (except dup puts) */
> -    if ( client->frozen )
> -        goto free;
> -
> -    if ( (objfound == NULL) )
> +    else
>      {
> +        /* no puts allowed into a frozen pool (except dup puts) */
> +        if ( client->frozen )
> +            return ret;
>          tmem_write_lock(&pool->pool_rwlock);
> -        if ( (obj = objnew = obj_new(pool,oidp)) == NULL )
> +        if ( (obj = obj_new(pool,oidp)) == NULL )
>          {
>              tmem_write_unlock(&pool->pool_rwlock);
>              return -ENOMEM;
>          }
> -        ASSERT_SPINLOCK(&objnew->obj_spinlock);
> +        newobj= 1;

Space before '='

>          tmem_write_unlock(&pool->pool_rwlock);
>      }
>  
> -    ASSERT((obj != 
> NULL)&&((objnew==obj)||(objfound==obj))&&(objnew!=objfound));
> +    /* When arrive here, we have a spinlocked obj for use */
>      ASSERT_SPINLOCK(&obj->obj_spinlock);
>      if ( (pgp = pgp_alloc(obj)) == NULL )
> -        goto free;
> +        goto unlock_obj;
>  
>      ret = pgp_add_to_obj(obj, index, pgp);
>      if ( ret == -ENOMEM  )
>          /* warning, may result in partially built radix tree ("stump") */
> -        goto free;
> -    ASSERT(ret != -EEXIST);
> +        goto free_pgp;
> +
>      pgp->index = index;
>      pgp->size = 0;
> -

Stray. But that might not really matter as this is a cleanup patch after all.

>      if ( client->compress )
>      {
>          ASSERT(pgp->pfp == NULL);
> @@ -1562,7 +1568,7 @@ static int do_tmem_put(struct tmem_pool *pool,
>          if ( ret == -ENOMEM )
>          {
>              client->compress_nomem++;
> -            goto delete_and_free;
> +            goto del_pgp_from_obj;
>          }
>          if ( ret == 0 )
>          {
> @@ -1577,15 +1583,16 @@ copy_uncompressed:
>      if ( ( pgp->pfp = tmem_page_alloc(pool) ) == NULL )
>      {
>          ret = -ENOMEM;
> -        goto delete_and_free;
> +        goto del_pgp_from_obj;
>      }
>      ret = tmem_copy_from_client(pgp->pfp, cmfn, clibuf);
>      if ( ret < 0 )
>          goto bad_copy;
> +
>      if ( tmem_dedup_enabled() && !is_persistent(pool) )
>      {
>          if ( pcd_associate(pgp,NULL,0) == -ENOMEM )
> -            goto delete_and_free;
> +            goto del_pgp_from_obj;
>      }
>  
>  insert_page:
> @@ -1601,18 +1608,23 @@ insert_page:
>          if (++client->eph_count > client->eph_count_max)
>              client->eph_count_max = client->eph_count;
>          tmem_spin_unlock(&eph_lists_spinlock);
> -    } else { /* is_persistent */
> +    }
> +    else
> +    { /* is_persistent */

So StyleGuide fixes too, in which case you might as well:
>          tmem_spin_lock(&pers_lists_spinlock);
>          list_add_tail(&pgp->us.pool_pers_pages,
>              &pool->persistent_page_list);
>          tmem_spin_unlock(&pers_lists_spinlock);
>      }
> -    ASSERT( ((objnew==obj)||(objfound==obj)) && (objnew!=objfound));
> +
>      if ( is_shared(pool) )
>          obj->last_client = client->cli_id;
>      obj->no_evict = 0;
> +
> +    /* free the obj spinlock */
>      tmem_spin_unlock(&obj->obj_spinlock);
>      pool->good_puts++;
> +
>      if ( is_persistent(pool) )
>          client->succ_pers_puts++;
>      else
> @@ -1622,25 +1634,24 @@ insert_page:
>  bad_copy:
>      failed_copies++;
>  
> -delete_and_free:
> +del_pgp_from_obj:
>      ASSERT((obj != NULL) && (pgp != NULL) && (pgp->index != -1));
> -    pgpdel = pgp_delete_from_obj(obj, pgp->index);
> -    ASSERT(pgp == pgpdel);
> +    pgp_delete_from_obj(obj, pgp->index);
>  
> -free:
> -    if ( pgp )
> -        pgp_delete(pgp,0);
> -    if ( objfound )
> -    {
> -        objfound->no_evict = 0;
> -        tmem_spin_unlock(&objfound->obj_spinlock);
> -    }
> -    if ( objnew )
> +free_pgp:
> +    pgp_delete(pgp,0);

.. fix that.
> +unlock_obj:
> +    if ( newobj )
>      {
>          tmem_write_lock(&pool->pool_rwlock);
> -        obj_free(objnew,0);
> +        obj_free(obj,0);

.. and that.

>          tmem_write_unlock(&pool->pool_rwlock);
>      }
> +    else
> +    {
> +        obj->no_evict = 0;
> +        tmem_spin_unlock(&obj->obj_spinlock);
> +    }
>      pool->no_mem_puts++;
>      return ret;
>  }
> -- 
> 1.7.10.4
> 

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