StackOverflow2013

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POHow could I simulate the race condition scenario in an interrupt code
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copied!<p>I am a beginner in learning Linux device driver. I wrote a keyboard driver:</p> <pre><code>#include <linux/init.h> #include <linux/module.h> #include <linux/interrupt.h> #include <asm/io.h> /* This function services keyboard interrupts. */ int packetNumber=3000; EXPORT_SYMBOL(packetNumber); irqreturn_t irq_handler (int irq, void *dev_id, struct pt_regs *regs) { static unsigned char scancode; /* Read keyboard status */ scancode = inb (0x60); if (scancode == 0x01) { packetNumber += 10; printk(KERN_ALERT "packetNumber:%x\n",&packetNumber); printk (KERN_ALERT "You pressed Esc ! packetNumber: %d\n", packetNumber); } return (irqreturn_t) IRQ_HANDLED; } /* Initialize the module ? register the IRQ handler */ static int hello_keyboard (void) { /* Request IRQ 1, the keyboard IRQ, to go to our irq_handler SA_SHIRQ means we're willing to have othe handlers on this IRQ. SA_INTERRUPT can be used to make the handler into a fast interrupt. */ packetNumber += 10; printk(KERN_ALERT "hello, keyboard.%d\n", packetNumber); return request_irq (1, (irqreturn_t) irq_handler, SA_SHIRQ, "test_keyboard_irq_handler", (void *)(irq_handler)); } static void bye_keyboard(void) { printk(KERN_ALERT "Goodbye, keyboard\n"); } module_init(hello_keyboard); module_exit(bye_keyboard); MODULE_AUTHOR("e-Friends"); MODULE_LICENSE("Dual BSD/GPL"); MODULE_DESCRIPTION("a simple keyboard driver."); </code></pre> <p>I want to use this keyboard driver to simulate the race condition scenario like this: <a href="http://ww3.sinaimg.cn/mw690/5f10acdbjw1ealisec0frj20lk0e8gnm.jpg" rel="nofollow">http://ww3.sinaimg.cn/mw690/5f10acdbjw1ealisec0frj20lk0e8gnm.jpg</a></p> <hr> <p>I don't understand very much about the image above.</p> <blockquote> <p>For simulating the scenario, I want to know:</p> </blockquote> <ul> <li>Where the main_task function should be? in the driver, or a user application using the driver? </li> <li>If main_task function should be in the user application, how could I define the packetNumber variable to let both interrupt handler and user application can use this same variable?</li> </ul> <p>ps: I temporarily use the packetNumber variable in the init function(hello_keyboard function), does it right?</p>

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