On Tue, 11 Sep 2007 06:20:51 -0700 (PDT) Matti Linnanvuori <[EMAIL PROTECTED]> wrote:
Hi, > I thought of a scenario where it seems appropriate to use a binary > semaphore or a mutex in a software interrupt context. If a device > cannot interrupt when some important variable changes, it can be > polled occasionally to update e.g. LEDs to indicate status. Such > polling can be done most efficiently in timers that are software > interrupts. Timers are more efficient than works because they do not > have so much context switching overhead. If the access to the > variables of the device must be serialized, a binary semaphore or a > mutex is a natural choice. If user-space writing to the device is > likely to change the status, it can make sense not to poll the status > of the device at the same time. The timer could therefore sensibly > call mutex_trylock. what do you do if the trylock fails? > Therefore, it seems wrong to me to deprecate > binary semaphores and disallow the use of mutexes in software > interrupt contexts. to be honest, the scenario describe really smells of broken locking, in fact it really sounds like it wants to use spinlocks instead Greetings, Arjan van de Ven - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
