On Feb 27, 2005, at 18:38, Wen Xiong wrote:
+/* + * jsm_init_globals() + * + * This is where we initialize the globals from the static insmod + * configuration variables. These are declared near the head of + * this file. + */ +static void jsm_init_globals(void) +{ + int i = 0; + + jsm_rawreadok = rawreadok; + jsm_trcbuf_size = trcbuf_size; + jsm_debug = debug; + + for (i = 0; i < MAXBOARDS; i++) { + jsm_Board[i] = NULL; + jsm_board_slot[i] = (char *)kmalloc(20, GFP_KERNEL); + memset(jsm_board_slot[i], 0, 20); + }
Instead of several 20-byte kmallocs, you could help reduce memory usage and fragmentation with something like this:
static void *jsm_board_slot_mem;
jsm_board_slot_mem = kmalloc(20*MAXBOARDS, GFP_KERNEL); memset(jsm_board_slot_mem, 0, 20*MAXBOARDS) for (i = 0; i < MAXBOARDS; i++) { jsm_Board[i] = NULL; jsm_board_slot[i] = &jsm_board_slot_mem[20*i]; }
Then free like this: kfree(jsm_board_slot_mem);
Agree with your initial comment, but you missed an overall point: MAXBOARDS must be eliminated completely. We do not impose such limits in Linux.
Information should be allocated on a per-device basis.
On the other hand, it might be nice to have all these structures dynamically allocated, so that the no-boards case only uses the 8 or 16 bytes of RAM required for a struct list_head. In that case you could clump the other board info into a single struct instead of multiple independent static arrays. Something like this might work:
struct jsm_board_instance { struct list_head board_list; struct board_t board; char slot[20]; [...etc...] }; static struct list_head jsm_board_list = LIST_HEAD_INIT(jsm_board_list); static spinlock_t jsm_board_list_lock = SPIN_LOCK_UNLOCKED;
Then when doing hardware add/remove, take the lock and do the list manipulation, then unlock.
Correct-a-mundo!
This is the way it should be done.
Jeff
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