Re: [PATCH 2/4] mini-os: mm: remove not needed struct chunk_tail_st

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Juergen Gross, le lun. 22 juil. 2024 17:01:39 +0200, a ecrit:
> The struct chunk_tail_st isn't really used other than writing to it.
> 
> Remove it in order to simplify the code.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

> ---
>  mm.c | 20 --------------------
>  1 file changed, 20 deletions(-)
> 
> diff --git a/mm.c b/mm.c
> index 1dcd954c..2cc49e94 100644
> --- a/mm.c
> +++ b/mm.c
> @@ -123,7 +123,6 @@ static void map_free(unsigned long first_page, unsigned 
> long nr_pages)
>  /* BINARY BUDDY ALLOCATOR */
>  
>  typedef struct chunk_head_st chunk_head_t;
> -typedef struct chunk_tail_st chunk_tail_t;
>  
>  struct chunk_head_st {
>      chunk_head_t  *next;
> @@ -131,10 +130,6 @@ struct chunk_head_st {
>      int            level;
>  };
>  
> -struct chunk_tail_st {
> -    int level;
> -};
> -
>  /* Linked lists of free chunks of different powers-of-two in size. */
>  #define FREELIST_SIZE ((sizeof(void *) << 3) - PAGE_SHIFT)
>  static chunk_head_t *free_head[FREELIST_SIZE];
> @@ -151,7 +146,6 @@ static void init_page_allocator(unsigned long min, 
> unsigned long max)
>      unsigned long range;
>      unsigned long r_min, r_max;
>      chunk_head_t *ch;
> -    chunk_tail_t *ct;
>  
>      printk("MM: Initialise page allocator for %lx(%lx)-%lx(%lx)\n",
>             (u_long)to_virt(min), min, (u_long)to_virt(max), max);
> @@ -215,14 +209,12 @@ static void init_page_allocator(unsigned long min, 
> unsigned long max)
>              ch = (chunk_head_t *)r_min;
>              r_min += 1UL << i;
>              range -= 1UL << i;
> -            ct = (chunk_tail_t *)r_min - 1;
>              i -= PAGE_SHIFT;
>              ch->level       = i;
>              ch->next        = free_head[i];
>              ch->pprev       = &free_head[i];
>              ch->next->pprev = &ch->next;
>              free_head[i]    = ch;
> -            ct->level       = i;
>          }
>      }
>  
> @@ -234,7 +226,6 @@ unsigned long alloc_pages(int order)
>  {
>      int i;
>      chunk_head_t *alloc_ch, *spare_ch;
> -    chunk_tail_t            *spare_ct;
>  
>      if ( !chk_free_pages(1UL << order) )
>          goto no_memory;
> @@ -261,14 +252,11 @@ unsigned long alloc_pages(int order)
>          i--;
>          spare_ch = (chunk_head_t *)((char *)alloc_ch +
>                                      (1UL << (i + PAGE_SHIFT)));
> -        spare_ct = (chunk_tail_t *)((char *)spare_ch +
> -                                    (1UL << (i + PAGE_SHIFT))) - 1;
>  
>          /* Create new header for spare chunk. */
>          spare_ch->level = i;
>          spare_ch->next  = free_head[i];
>          spare_ch->pprev = &free_head[i];
> -        spare_ct->level = i;
>  
>          /* Link in the spare chunk. */
>          spare_ch->next->pprev = &spare_ch->next;
> @@ -289,7 +277,6 @@ EXPORT_SYMBOL(alloc_pages);
>  void free_pages(void *pointer, int order)
>  {
>      chunk_head_t *freed_ch, *to_merge_ch;
> -    chunk_tail_t *freed_ct;
>      unsigned long mask;
>  
>      /* First free the chunk */
> @@ -297,8 +284,6 @@ void free_pages(void *pointer, int order)
>  
>      /* Create free chunk */
>      freed_ch = (chunk_head_t *)pointer;
> -    freed_ct = (chunk_tail_t *)((char *)pointer +
> -                                (1UL << (order + PAGE_SHIFT))) - 1;
>  
>      /* Now, possibly we can conseal chunks together */
>      while ( order < FREELIST_SIZE )
> @@ -320,9 +305,6 @@ void free_pages(void *pointer, int order)
>              if ( allocated_in_map(virt_to_pfn(to_merge_ch)) ||
>                   to_merge_ch->level != order )
>                  break;
> -
> -            /* Merge with successor */
> -            freed_ct = (chunk_tail_t *)((char *)to_merge_ch + mask) - 1;
>          }
>  
>          /* We are committed to merging, unlink the chunk */
> @@ -336,8 +318,6 @@ void free_pages(void *pointer, int order)
>      freed_ch->level = order;
>      freed_ch->next  = free_head[order];
>      freed_ch->pprev = &free_head[order];
> -    freed_ct->level = order;
> -
>      freed_ch->next->pprev = &freed_ch->next;
>      free_head[order] = freed_ch;
>  
> -- 
> 2.43.0
> 

-- 
Samuel
/*
 * [...] Note that 120 sec is defined in the protocol as the maximum
 * possible RTT.  I guess we'll have to use something other than TCP
 * to talk to the University of Mars.
 * PAWS allows us longer timeouts and large windows, so once implemented
 * ftp to mars will work nicely.
 */
(from /usr/src/linux/net/inet/tcp.c, concerning RTT [retransmission timeout])