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.smp_lock.h#ifndef __I386_SMPLOCK_H#define __I386_SMPLOCK_H#ifdef __SMP__/** Locking the kernel*/extern __inline void lock_kernel(void){unsigned long flags;int proc = smp_processor_id();save_flags(flags);cli();/* set_bit works atomic in SMP machines */while(set_bit(0, (void *)&kernel_flag)){/** We just start another level if we have the lock*/if (proc == active_kernel_processor)break;do{#ifdef __SMP_PROF__smp_spins[smp_processor_id()]++;#endif/** Doing test_bit here doesn't lock the bus*/if (test_bit(proc, (void *)&smp_invalidate_needed))if (clear_bit(proc, (void *)&smp_invalidate_needed))local_flush_tlb();}while(test_bit(0, (void *)&kernel_flag));}/** We got the lock, so tell the world we are here and increment* the level counter*/active_kernel_processor = proc;kernel_counter++;restore_flags(flags);}extern __inline void unlock_kernel(void){unsigned long flags;save_flags(flags);cli();/** If it's the last level we have in the kernel, then* free the lock*/if (kernel_counter == 0)panic("Kernel counter wrong.\n"); /* FIXME: Why is kernel_counter sometimes 0 here? */if(! --kernel_counter){active_kernel_processor = NO_PROC_ID;clear_bit(0, (void *)&kernel_flag);}restore_flags(flags);}#endif#endif
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