On 3/22/06, Bennett, Robert P <Robert.Bennett@xxxxxx> wrote: > > > -----Original Message----- > > From: kernelnewbies-bounce@xxxxxxxxxxxx > > [mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of pradeep singh > > Sent: Wednesday, March 22, 2006 9:59 AM > > To: kernel-issues > > Subject: spinlocks and kernel timer !!! > > > > > > Hi > > > > static void some_method() > > { > > unsigned long expires; > > static struct timer_list *timer; > > expires = jiffes + 20; > > data = 5; > > timer->expires = expires; > > timer->function = my_function; > > timer->data = data; > > init_timer(timer); /*initalise timer*/ > > spin_lock_irqsave(&spinlock, iflags); > > spin_unlock_irqrestore(&spinlock, iflags); > > > > return 0; > > } > > > > static int __init mod_init( void ) > > { > > printk(KERN_DEBUG "in init..\n"); > > some_method(); > > printk(KERN_DEBUG "after some method in init..\n"); > > > > return 0; > > }; > > > > static void __exit mod_exit( void ) > > { > > printk(KERN_DEBUG "bye world...\n"); > > > > } > > > > My question is between spin_lock_irqsave() and > > spin_unlock_irqrestore() code is supposed to be atomic right? > > Now as i have initialised a timer structure in the > > function.If the jiffies gets equal to expires in between > > spinlock() and spinunlock() will my_function() execute? > > > > What will happen and why? > > You will OOPS as soon as you dereference "timer", since you did > not initialize it. does this means init_timer( timer ) will not initialise the timer ? I think LDD3 says about init_timer(timer) to initialise the timer :), where am i getting this all wrong ? Can you please explain ? thank you > As for the behavior of the timer, I would expect that nothing is > going to happen until after the > spin_unlock_irqrestore() has been executed, since local > interrupts are disabled. > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
