Re: semaphore understanding: sys_semtimedop()

[randy_dunlap]

On Mon, 16 May 2005 22:17:04 +0200 Patrick Plattes wrote:

| Hello,
| 
| i have a question about this little code snippet, found in
| sys_semtimedop() (ipc/sem.c):
| 
|         for (sop = sops; sop < sops + nsops; sop++) {
|                 if (sop->sem_num >= max)
|                         max = sop->sem_num;
|                 if (sop->sem_flg & SEM_UNDO)
|                         undos++;
|                 if (sop->sem_op < 0)
|                         decrease = 1;
|                 if (sop->sem_op > 0)
|                         alter = 1;
|         }
|         alter |= decrease;
| 
| The variable decrease will never be used again in this 
| function, so why this intricate code? Isn't this much easier and works
| also:
| 
|         for (sop = sops; sop < sops + nsops; sop++) {
|                 if (sop->sem_num >= max)
|                         max = sop->sem_num;
|                 if (sop->sem_flg & SEM_UNDO)
|                         undos++;
|                 if (sop->sem_op != 0)
|                         alter = 1;
|         }
| 
| Maybe i'm totally wrong, so please correct me and don't shoot me up,
| 'cause i'm not a os developer.

Looks like a reasonable and correct optimization to me.

Let's see what Manfred thinks or has to say...

---
~Randy
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