I noticed that sysv semaphores initialize the otime member of the semid_ds structure to 0, but they never update it afterwards. This field is supposed to be the last operation time. ie the last time a semctl was done. In UNIX Network Programming, Stevens suggests using this variable to detect races between multiple processes creating/accessing a sysv semaphore. Anyway, I looked through the code and came up with the following trivial patch. Could some one review it and perhaps commit it? This patch was made against current, but I noticed the bug is there in 4.1.1 and most likely everything before that.
Thanks,
Jeff
(Pardon the revision numbers, they are from my own repository)
*** sysv_sem.c 2000/09/15 11:11:48 1.1.1.1
--- sysv_sem.c 2000/12/12 23:44:28
***************
*** 543,548 ****
--- 543,550 ----
return(EINVAL);
}
+ semaptr->sem_otime = time_second;
+
if (eval == 0)
p->p_retval[0] = rval;
return(eval);
