Mity CPU Platforms » MityDSP-L138 (ARM9 Based Platforms)

Hi,

I tried to run a trivial test driver pasted in below on a PC using Redhat linux and on the ARM core of the OMAP-138 using Angstrom linux. The function "spinlock_test" trys to obtain a spinlock it has already by calling itself two times. On the PC, it causes a deadlock as expected. On the ARM, it just runs fine, means I can load and unload the module without problems. That means, on the ARM the spinlocks work recursively which contradicts everything I read about linux spinlocks. Seems to be a kernel configuration or architecture specific problem ? Any idea ? Kernel config on the ARM attached.

#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("Dual BSD/GPL");

spinlock_t lock;

void spinlock_test(void) {
static int cnt = 0;
if(cnt < 3) {
cnt++;
printk("////////////////// spinlock_test:%d\n", cnt);
spin_lock(&lock);
spinlock_test();
}
else {
printk("////////////////// spinlock_test finished:\n");
spin_unlock(&lock);
spin_unlock(&lock);
spin_unlock(&lock);
cnt = 0;
}
}

static int hello_init(void) {
printk(KERN_ALERT "Hello, world\n");
spin_lock_init(&lock);
spinlock_test();

return 0;
}

static void hello_exit(void) {
printk(KERN_ALERT "Goodbye, cruel world\n");
}

module_init(hello_init);
module_exit(hello_exit);