How to avoid kernel blocking while running a module in uclinux2.4?

cricketlong · 09-19-2009, 09:13 AM

My intention:
running a music playing module and allow the kernel to do any other things at the same time.

I use the section of C code bellow for kt module:

Code:

int kt_handler(unsigned long data)
{
    int i, j;
    for(i = 0;i < 10000;i++)
        for(j = 0;j < 10000;j++){}
    complete(&kt_cpl);
    return 0;
}

int kt_read(struct inode *inode, struct file *filp, char *buf, unsigned long cmd)
{
    kernel_thread(kt_handler, NULL, CLONE_VM|SIGCHLD);
    printk("Waiting for completion......\n");
    wait_for_completion(&kt_cpl);
    printk("Completed. Continue......\n");
    return 0;
}

I open the module with the following line:

Code:

open("/dev/kt", O_RDWR);

output:
Waiting for completion......
(stops here for more than 5 seconds)
Completed. Continue......

smeezekitty · 09-20-2009, 02:33 AM

i am just gussing but try
changing

Code:

 for(j = 0;j < 10000;j++){}

to

Code:

 for(j = 0;j < 10000;j++){usleep(10);}

please try and tell me the result

cricketlong · 09-20-2009, 07:55 AM

it seems that usleep is not available in a module

I compiled and got error bellow:
drivers/char/char.o(.text+0xa028): In function `kt_handler':
: undefined reference to `usleep'
make[1]: *** [linux] Error 1
make[1]: Leaving directory `/root/uClinux-dist/linux-2.4.x'
make: *** [linux] Error 1

cricketlong · 09-26-2009, 10:59 PM

Can any body help me?

smeezekitty · 09-26-2009, 11:27 PM

forums are dead right now

virtualCoder · 09-27-2009, 01:58 AM

If you are trying to use usleep, did you add: #include <unistd.h>
If I understood your question correctly, you are trying to sleep for 5 secs, then you can also use:
#include <unistd.h>
unsigned int sleep(unsigned int seconds);

So sleep(5); // sleep for 5 seconds.

smeezekitty · 09-27-2009, 08:52 PM

Quote:

Originally Posted by virtualCoder

If you are trying to use usleep, did you add: #include <unistd.h>
If I understood your question correctly, you are trying to sleep for 5 secs, then you can also use:
#include <unistd.h>
unsigned int sleep(unsigned int seconds);

So sleep(5); // sleep for 5 seconds.

no its a linker error so adding include files wont help

cricketlong · 09-28-2009, 12:57 AM

Quote:

Originally Posted by smeezekitty

no its a linker error so adding include files wont help

agree, include files can only make affection during compiling.