source: trunk/kernel/libk/remote_spinlock.c @ 408

/*
 * remote_spinlock.c - kernel remote spinlock implementation.
 *
 * Authors  Mohamed Karaoui (2015)
 *          Alain   Greiner (2016)
 *
 * Copyright (c) UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-MKH.
 *
 * ALMOS-MKH is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-MKH is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <hal_types.h>
#include <hal_remote.h>
#include <hal_irqmask.h>
#include <thread.h>
#include <cluster.h>
#include <scheduler.h>
#include <remote_spinlock.h>

///////////////////////////////////////////
void remote_spinlock_init( xptr_t lock_xp )
{
        remote_spinlock_t * ptr = (remote_spinlock_t *)GET_PTR( lock_xp );
        cxy_t               cxy = GET_CXY( lock_xp );

        hal_remote_sw ( XPTR( cxy , &ptr->taken ) , 0 );
        hal_remote_swd( XPTR( cxy , &ptr->owner ) , XPTR_NULL );
        xlist_entry_init( XPTR( cxy , &ptr->list ) );
}

/////////////////////////////////////////////////
error_t remote_spinlock_trylock( xptr_t lock_xp )
{
        reg_t               mode;
        bool_t              isAtomic = false;

        // get cluster and local pointer on remote_spinlock
        remote_spinlock_t * lock_ptr = (remote_spinlock_t *)GET_PTR( lock_xp );
        cxy_t               lock_cxy = GET_CXY( lock_xp );

        // get cluster and local pointer on local thread
        cxy_t               thread_cxy = local_cxy;
        thread_t          * thread_ptr = CURRENT_THREAD;

        // disable interrupts
        hal_disable_irq( &mode );

        if( hal_remote_lw( XPTR( lock_cxy , &lock_ptr->taken ) ) == 0 )
        {
                isAtomic = hal_remote_atomic_cas( XPTR( lock_cxy , &lock_ptr->taken ) , 0 , 1 );
        }

        if( isAtomic == false )    // failure
        {
                hal_restore_irq( mode );
                return 1;
        }
        else                      // success : register lock in thread
        {
                thread_ptr->remote_locks++;

                hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) ,
                            (uint64_t)XPTR( thread_cxy , thread_ptr) );

                xlist_add_first( XPTR( thread_cxy , &thread_ptr->xlocks_root ) ,
                             XPTR( lock_cxy , &lock_ptr->list ) );

                hal_restore_irq(mode);
                return 0;
        }
}

///////////////////////////////////////////////////
void remote_spinlock_lock_busy( xptr_t     lock_xp,
                                uint32_t * irq_state )
{
        bool_t              isAtomic = false;
        reg_t               mode;
        volatile uint32_t   taken;

        // get cluster and local pointer on remote_spinlock
        remote_spinlock_t * lock_ptr = (remote_spinlock_t *)GET_PTR( lock_xp );
        cxy_t               lock_cxy = GET_CXY( lock_xp );

        // get cluster and local pointer on local thread
        cxy_t               thread_cxy = local_cxy;
        thread_t          * thread_ptr = CURRENT_THREAD;

        // disable interrupts
        hal_disable_irq( &mode );

        // loop until success
        while( isAtomic == false )
        {
                taken = hal_remote_lw( XPTR( lock_cxy , &lock_ptr->taken ) );

                // try to take the lock if not already taken
                if( taken == 0 )
                {
                        isAtomic = hal_remote_atomic_cas( XPTR( lock_cxy , &lock_ptr->taken ) , 0 , 1 );
                }
        }

        // register lock in thread
        thread_ptr->remote_locks++;

        hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) ,
                        (uint64_t)XPTR( thread_cxy , thread_ptr) );

        xlist_add_first( XPTR( thread_cxy , &thread_ptr->xlocks_root ) ,
                         XPTR( lock_cxy , &lock_ptr->list ) );

        // irq_state must be restored when lock is released
        *irq_state = mode;

}  // end remote_spinlock_lock_busy()

////////////////////////////////////////////////////
void remote_spinlock_unlock_busy( xptr_t    lock_xp,
                                  uint32_t  irq_state )
{
        // get cluster and local pointer on remote_spinlock
        remote_spinlock_t * lock_ptr = (remote_spinlock_t *)GET_PTR( lock_xp );
        cxy_t               lock_cxy = GET_CXY( lock_xp );

        // get pointer on local thread
        thread_t          * thread_ptr = CURRENT_THREAD;

        hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) , XPTR_NULL );
        hal_remote_sw ( XPTR( lock_cxy , &lock_ptr->taken ) , 0 );
        thread_ptr->remote_locks--;
        xlist_unlink( XPTR( lock_cxy , &lock_ptr->list ) );

    // deschedule if pending request
    thread_check_sched();
 
    // restore IRQs
        hal_restore_irq( irq_state );
}

///////////////////////////////////////////
void remote_spinlock_lock( xptr_t lock_xp )
{
        bool_t              isAtomic = false;
        reg_t               mode;
        volatile uint32_t   taken;

        // get cluster and local pointer on remote_spinlock
        remote_spinlock_t * lock_ptr = (remote_spinlock_t *)GET_PTR( lock_xp );
        cxy_t               lock_cxy = GET_CXY( lock_xp );

    // get cluster and local pointer on calling thread
    cxy_t               thread_cxy = local_cxy;
    thread_t          * thread_ptr = CURRENT_THREAD;

        // disable interrupts
        hal_disable_irq( &mode );

        // loop until success
        while( isAtomic == false )
        {
                taken = hal_remote_lw( XPTR( lock_cxy , &lock_ptr->taken ) );

                // deschedule if possible when lock already taken
                if( taken != 0 )
                {
                        hal_restore_irq( mode );
                        if( thread_can_yield() ) sched_yield("waiting spinlock");
                        hal_disable_irq( &mode );
                        continue;
                }

                // try to take the lock if not already taken
                isAtomic = hal_remote_atomic_cas( XPTR( lock_cxy , &lock_ptr->taken ) , 0 , 1 );
        }

        // register lock in thread
        thread_ptr->remote_locks++;

        hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) ,
                        (uint64_t)XPTR( thread_cxy , thread_ptr) );

        xlist_add_first( XPTR( thread_cxy , &thread_ptr->xlocks_root ) ,
                         XPTR( lock_cxy , &lock_ptr->list ) );

        // enable interrupts
        hal_restore_irq( mode );
}

/////////////////////////////////////////////
void remote_spinlock_unlock( xptr_t lock_xp )
{
        // get cluster and local pointer on remote_spinlock
        remote_spinlock_t * lock_ptr = (remote_spinlock_t *)GET_PTR( lock_xp );
        cxy_t               lock_cxy = GET_CXY( lock_xp );

        // get pointer on local thread
        thread_t          * thread_ptr = CURRENT_THREAD;

        hal_remote_swd( XPTR( lock_cxy , &lock_ptr->owner ) , XPTR_NULL );
        hal_remote_sw ( XPTR( lock_cxy , &lock_ptr->taken ) , 0 );
        thread_ptr->remote_locks--;
        xlist_unlink( XPTR( lock_cxy , &lock_ptr->list ) );

    // deschedule if pending request
    thread_check_sched();
}

//////////////////////////////////////////////
xptr_t remote_spinlock_owner( xptr_t lock_xp )
{
    // get cluster and local pointer on remote_spinlock
    remote_spinlock_t * lock_ptr = (remote_spinlock_t *)GET_PTR( lock_xp );
    cxy_t               lock_cxy = GET_CXY( lock_xp );

    return hal_remote_lw( XPTR( lock_cxy , &lock_ptr->owner ) );
}