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author | Joel Sherrill <joel.sherrill@OARcorp.com> | 1995-07-12 19:47:25 +0000 |
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committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 1995-07-12 19:47:25 +0000 |
commit | 637df35f96d8023056369fcf2c9943419f1a1b74 (patch) | |
tree | a12bd461bf892ccaff6c67571432f0535eb03e96 /c/src/lib/libbsp/unix/posix/shmsupp/lock.c | |
parent | added David Glessner's 68302 work. (diff) | |
download | rtems-637df35f96d8023056369fcf2c9943419f1a1b74.tar.bz2 |
Ada95, gnat, go32
Diffstat (limited to '')
-rw-r--r-- | c/src/lib/libbsp/unix/posix/shmsupp/lock.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/unix/posix/shmsupp/lock.c b/c/src/lib/libbsp/unix/posix/shmsupp/lock.c new file mode 100644 index 0000000000..da39cc86f5 --- /dev/null +++ b/c/src/lib/libbsp/unix/posix/shmsupp/lock.c @@ -0,0 +1,117 @@ +/* Shared Memory Lock Routines + * + * This shared memory locked queue support routine need to be + * able to lock the specified locked queue. Interrupts are + * disabled while the queue is locked to prevent preemption + * and deadlock when two tasks poll for the same lock. + * previous level. + * + * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. + * On-Line Applications Research Corporation (OAR). + * All rights assigned to U.S. Government, 1994. + * + * This material may be reproduced by or for the U.S. Government pursuant + * to the copyright license under the clause at DFARS 252.227-7013. This + * notice must appear in all copies of this file and its derivatives. + * + * $Id$ + */ + +#include <rtems.h> + +#include <bsp.h> +#include <shm.h> + +#include <errno.h> +#include <stdio.h> +#include <unistd.h> +#include <sys/ipc.h> +#include <sys/shm.h> +#include <sys/sem.h> + +extern int semid; + +/* + * Shm_Initialize_lock + * + * Initialize the lock for the specified locked queue. + */ + +void Shm_Initialize_lock( + Shm_Locked_queue_Control *lq_cb +) +{ + lq_cb->lock = + ( lq_cb - Shm_Locked_queues ) / sizeof( Shm_Locked_queue_Control ); +} + +/* Shm_Lock( &lq_cb ) + * + * This shared memory locked queue support routine locks the + * specified locked queue. It disables interrupts to prevent + * a deadlock condition. + */ + +void Shm_Lock( + Shm_Locked_queue_Control *lq_cb +) +{ + rtems_unsigned32 isr_level; + struct sembuf sb; + int status; + + isr_level = 0; + + sb.sem_num = lq_cb->lock; + sb.sem_op = -1; + sb.sem_flg = 0; + rtems_interrupt_disable( isr_level ); + + Shm_isrstat = isr_level; + + while (1) { + status = semop(semid, &sb, 1); + if ( status == 0 ) + break; + if ( status == -1 && errno == EINTR ) + continue; + + fprintf( stderr, "shm lock (%d %d)\n", status, errno ); + exit( 0 ); + } +} + +/* + * Shm_Unlock + * + * Unlock the lock for the specified locked queue. + */ + +void Shm_Unlock( + Shm_Locked_queue_Control *lq_cb +) +{ + rtems_unsigned32 isr_level; + struct sembuf sb; + int status; + + isr_level = 0; + + sb.sem_num = lq_cb->lock; + sb.sem_op = 1; + sb.sem_flg = 0; + + while (1) { + status = semop(semid, &sb, 1); + if ( status == 0 ) + break; + if ( status == -1 && errno == EINTR ) + continue; + + fprintf( stderr, "shm lock (%d %d)\n", status, errno ); fflush( stderr ); + exit( 0 ); + } + + isr_level = Shm_isrstat; + rtems_interrupt_enable( isr_level ); +} |