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#include <pthread.h>
#include "linux/preempt.h"
/*
* In userspace, pthreads are preemptible and can migrate CPUs at any time.
*
* In the kernel, preempt_disable() logic essentially guarantees that a marked
* critical section owns its CPU for the relevant block. This is necessary for
* various code paths, critically including the percpu system as it allows for
* non-atomic reads and writes to CPU-local data structures.
*
* The high performance userspace equivalent would be to use thread local
* storage to replace percpu data, but that would be complicated. It should be
* correct to instead guarantee mutual exclusion for the critical sections.
*/
static pthread_mutex_t preempt_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
void preempt_disable(void)
{
pthread_mutex_lock(&preempt_lock);
}
void preempt_enable(void)
{
pthread_mutex_unlock(&preempt_lock);
}
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