Hi folks,
I am modifying linux-2.4.18 for ARM (based on S3C2410), I enable only
the timer interrupt and disable all the others in "init" thread before
"execve("/sbin/init",argv_init,envp_init);" is taking place.
I also create two kernel threads by invoking "kernel_thread" right
after disbling the interrupts. This is how the kernel thread looks
like:
923 void eos_1(void)
- 924 {
| 925 DECLARE_WAITQUEUE(wait, current);
| 926
| 927 while (1)
|- 928 {
|| 929 printk("\n%s[%d], period:%d, deadline:%d, jiffies:%d.\n",
|| 930 current->comm, current->pid,
current->period, current->deadline, jiffies);
|| 931 eos_tail();
|| 932 }
| 933 }
905 #define eos_tail() \
- 906 do { \
| 907 static int deadline = 0; \
| 908 if ((current->deadline - jiffies) > 0) \
|- 909 { \
|| 910 deadline = current->deadline; \
|| 911 current->deadline = deadline + current->period; \
|| 912 sleep_on_timeout(&wait, (deadline - jiffies)); \
|| 913 } \
| 914 else \
|- 915 { \
|| 916 printk("\n!!! %s[%d] missed deadline !!!\n",
current->comm, current->pid); \
|| 917 return (0); \
|| 918 } \
| 919 } while(0)
Now I am trying to modify the "schedule" function. I insert the
following segment into schedule function after the part that
re-calculate counters --> if(unlikely(!c)).
|- 634 {
|| 635 int latch = 0;
|| 636
|| 637 list_for_each(tmp, &runqueue_head)
||- 638 {
||| 639 //p = list_entry(tmp, struct task_struct, run_list);
||| 640 latch = latch + 1;
||| 641 }
|| 642 printk("{%d}", latch);
|| 643 }
This is where weird thing happens! If I uncomment line 639, kernel
complains that I am passing an illegal value into "sleep_on_timeout",
which is called in my kernel thread inside "eos_tail". I copy both
line 637 and 639 from schedule itself (they were used to pick next job
to run).
I am simply doing copy & paste inside "schedule", can someone please
tell me what is happening ?
Thanks a lot,
--
James
cyu021@xxxxxxxxx
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