Re: [PATCH] minios: fix add_id_to_freelist(0)

[Samuel Thibault <samuel.thibault@eu.citrix.com>]

Hello,

Is there anything against that patch?

Samuel

Samuel Thibault, le Wed 18 Jun 2008 12:29:10 +0100, a écrit :
> minios: fix add_id_to_freelist(0)
> 
> add_id_to_freelist(0) would make get_id_from_freelist() always return 0.
> 
> Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>
> 
> diff -r 78f90b0f707f extras/mini-os/fs-front.c
> --- a/extras/mini-os/fs-front.c	Tue Jun 17 14:45:18 2008 +0100
> +++ b/extras/mini-os/fs-front.c	Wed Jun 18 12:23:59 2008 +0100
> @@ -136,8 +136,8 @@
>  again:    
>      old_id = freelist[0];
>      /* Note: temporal inconsistency, since freelist[0] can be changed by someone
> -     * else, but we are a sole owner of freelist[id], it's OK. */
> -    freelist[id] = old_id;
> +     * else, but we are a sole owner of freelist[id + 1], it's OK. */
> +    freelist[id + 1] = old_id;
>      new_id = id;
>      if(cmpxchg(&freelist[0], old_id, new_id) != old_id)
>      {
> @@ -154,7 +154,7 @@
>  
>  again:    
>      old_id = freelist[0];
> -    new_id = freelist[old_id];
> +    new_id = freelist[old_id + 1];
>      if(cmpxchg(&freelist[0], old_id, new_id) != old_id)
>      {
>          printk("Cmpxchg on freelist remove failed.\n");
> @@ -785,8 +785,8 @@
>      printk("Allocating request array for import %d, nr_entries = %d.\n",
>              import->import_id, import->nr_entries);
>      requests = xmalloc_array(struct fs_request, import->nr_entries);
> -    import->freelist = xmalloc_array(unsigned short, import->nr_entries);
> -    memset(import->freelist, 0, sizeof(unsigned short) * import->nr_entries);
> +    import->freelist = xmalloc_array(unsigned short, import->nr_entries + 1);
> +    memset(import->freelist, 0, sizeof(unsigned short) * (import->nr_entries + 1));
>      for(i=0; i<import->nr_entries; i++)
>      {
>  	/* TODO: that's a lot of memory */
> diff -r 78f90b0f707f extras/mini-os/netfront.c
> --- a/extras/mini-os/netfront.c	Tue Jun 17 14:45:18 2008 +0100
> +++ b/extras/mini-os/netfront.c	Wed Jun 18 12:25:47 2008 +0100
> @@ -38,7 +38,7 @@
>  struct netfront_dev {
>      domid_t dom;
>  
> -    unsigned short tx_freelist[NET_TX_RING_SIZE];
> +    unsigned short tx_freelist[NET_TX_RING_SIZE + 1];
>      struct semaphore tx_sem;
>  
>      struct net_buffer rx_buffers[NET_RX_RING_SIZE];
> @@ -70,14 +70,14 @@
>  
>  static inline void add_id_to_freelist(unsigned int id,unsigned short* freelist)
>  {
> -    freelist[id] = freelist[0];
> +    freelist[id + 1] = freelist[0];
>      freelist[0]  = id;
>  }
>  
>  static inline unsigned short get_id_from_freelist(unsigned short* freelist)
>  {
>      unsigned int id = freelist[0];
> -    freelist[0] = freelist[id];
> +    freelist[0] = freelist[id + 1];
>      return id;
>  }
>  

-- 
Samuel
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