driver spin lock and files_lock deadlock question
I have a driver that needs to be SMP-safe. It also has some code hooking into the net_rx_action softirq. So it takes a spinlock and disables the local bottom-half around its critical sections: spin_lock_bh(_lock). Now, I'm facing a deadlock under a particular sequence involving the files_lock: 1. CPU 0 takes driver_lock and then calls remove_proc_entry() which is hanging at spin_lock(_lock). 2. CPU 1 was in fput() which took files_lock; the softirq comes in at this point and attempts to take driver_lock and hangs forever. It seems this kind of a deadlock can happen with any kernel lock, not just files_lock. What's the driver's mistake here? Is it wrong to call remove_proc_entry() while holding another lock? What is the right thing to do? This is with the 2.4 kernel, BTW. thanks srini -- 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/
driver spin lock and files_lock deadlock question
I have a driver that needs to be SMP-safe. It also has some code hooking into the net_rx_action softirq. So it takes a spinlock and disables the local bottom-half around its critical sections: spin_lock_bh(driver_lock). Now, I'm facing a deadlock under a particular sequence involving the files_lock: 1. CPU 0 takes driver_lock and then calls remove_proc_entry() which is hanging at spin_lock(files_lock). 2. CPU 1 was in fput() which took files_lock; the softirq comes in at this point and attempts to take driver_lock and hangs forever. It seems this kind of a deadlock can happen with any kernel lock, not just files_lock. What's the driver's mistake here? Is it wrong to call remove_proc_entry() while holding another lock? What is the right thing to do? This is with the 2.4 kernel, BTW. thanks srini -- 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/
