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libblock: Use pthread_once() for initialization

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Enabling and disabling preemption as done for single core will not work
for SMP.  In the bdbuf initialization preemption handling can be avoided
in general by using pthread_once().
This commit is contained in:
Ralf Kirchner
2014-06-02 13:48:41 +02:00
committed by Sebastian Huber
parent 25f5730fe5
commit 606ed52568
1 changed files with 25 additions and 29 deletions
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cpukit/libblock/src/bdbuf.c
+25 -29
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@@ -35,6 +35,7 @@
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include <pthread.h>
#include <rtems.h>
#include <rtems/error.h>
@@ -137,8 +138,7 @@ typedef struct rtems_bdbuf_cache
rtems_id read_ahead_task; /**< Read-ahead task */
rtems_chain_control read_ahead_chain; /**< Read-ahead request chain */
bool read_ahead_enabled; /**< Read-ahead enabled */
bool initialised; /**< Initialised state. */
rtems_status_code init_status; /**< The initialization status */
} rtems_bdbuf_cache;
typedef enum {
@@ -168,7 +168,8 @@ typedef enum {
RTEMS_BDBUF_FATAL_SYNC_UNLOCK,
RTEMS_BDBUF_FATAL_TREE_RM,
RTEMS_BDBUF_FATAL_WAIT_EVNT,
RTEMS_BDBUF_FATAL_WAIT_TRANS_EVNT
RTEMS_BDBUF_FATAL_WAIT_TRANS_EVNT,
RTEMS_BDBUF_FATAL_ONCE
} rtems_bdbuf_fatal_code;
/**
@@ -218,6 +219,8 @@ static rtems_task rtems_bdbuf_read_ahead_task(rtems_task_argument arg);
*/
static rtems_bdbuf_cache bdbuf_cache;
static pthread_once_t rtems_bdbuf_once_state = PTHREAD_ONCE_INIT;
#if RTEMS_BDBUF_TRACE
/**
* If true output the trace message.
@@ -1385,13 +1388,8 @@ rtems_bdbuf_read_request_size (uint32_t transfer_count)
+ sizeof (rtems_blkdev_sg_buffer) * transfer_count;
}
/**
* Initialise the cache.
*
* @return rtems_status_code The initialisation status.
*/
rtems_status_code
rtems_bdbuf_init (void)
static rtems_status_code
rtems_bdbuf_do_init (void)
{
rtems_bdbuf_group* group;
rtems_bdbuf_buffer* bd;
@@ -1399,7 +1397,6 @@ rtems_bdbuf_init (void)
size_t b;
size_t cache_aligment;
rtems_status_code sc;
rtems_mode prev_mode;
if (rtems_bdbuf_tracer)
printf ("bdbuf:init\n");
@@ -1418,22 +1415,6 @@ rtems_bdbuf_init (void)
> RTEMS_MINIMUM_STACK_SIZE / 8U)
return RTEMS_INVALID_NUMBER;
/*
* We use a special variable to manage the initialisation incase we have
* completing threads doing this. You may get errors if the another thread
* makes a call and we have not finished initialisation.
*/
prev_mode = rtems_bdbuf_disable_preemption ();
if (bdbuf_cache.initialised)
{
rtems_bdbuf_restore_preemption (prev_mode);
return RTEMS_RESOURCE_IN_USE;
}
memset(&bdbuf_cache, 0, sizeof(bdbuf_cache));
bdbuf_cache.initialised = true;
rtems_bdbuf_restore_preemption (prev_mode);
/*
* For unspecified cache alignments we use the CPU alignment.
*/
@@ -1650,11 +1631,26 @@ error:
rtems_semaphore_delete (bdbuf_cache.lock);
}
bdbuf_cache.initialised = false;
return RTEMS_UNSATISFIED;
}
static void
rtems_bdbuf_init_once (void)
{
bdbuf_cache.init_status = rtems_bdbuf_do_init();
}
rtems_status_code
rtems_bdbuf_init (void)
{
int eno = pthread_once (&rtems_bdbuf_once_state, rtems_bdbuf_init_once);
if (eno != 0)
rtems_bdbuf_fatal (RTEMS_BDBUF_FATAL_ONCE);
return bdbuf_cache.init_status;
}
static void
rtems_bdbuf_wait_for_event (rtems_event_set event)
{