Hi, Le Fri, 21 Sep 2007 17:27:17 +0530, "Rajendra Stalekar" <rajendra.stalekar@xxxxxxxxx> a écrit : > [rajendra stalekar] AFAIK, spinlocks anyway disable interrupts, > however, once it gets unlocked it enables it. The reason why we call > spin_lock_irqsave could be that , if the interrupt did comes by, it > would be kept pending and then once it i.e. spin_lock_irqrestore , it > will invoke the interrupt handler. It depends which kind of locking you need. spin_lock() and spin_unlock() allows to take/release a spinlock, but they do not disable interrupts. On UP, they only disable preemption (if preemption is enabled). This is because spin_lock() and spin_unlock() only allows to protect against mutual access from two process contexts. On the opposite, spin_lock_irqsave() and spin_unlock_irqrestore() disable/enable the interrupts, because they are designed to provide mutual exclusion between process context and interrupt context. Have a look at http://free-electrons.com/kerneldoc/latest/DocBook/kernel-locking/index.html. Sincerly, Thomas -- Thomas Petazzoni - thomas.petazzoni@xxxxxxxx http://{thomas,sos,kos}.enix.org - http://www.toulibre.org http://www.{livret,agenda}dulibre.org -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
