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libblock: Fix read-ahead task wake-up

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In case the read-ahead task is not configured we must not send a wake-up
event.  This would send the wake-up event to the executing task.

We must send the wake-up event only in case the request list changes
from empty to non-empty.  Since otherwise we may send a false transfer
event.
This commit is contained in:
Sebastian Huber
2012-07-06 16:39:00 +02:00
parent 2cc4f3ca45
commit 5b29a08d69
1 changed files with 10 additions and 5 deletions
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15
cpukit/libblock/src/bdbuf.c
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@@ -2039,17 +2039,22 @@ static void
rtems_bdbuf_check_read_ahead_trigger (rtems_disk_device *dd,
rtems_blkdev_bnum block)
{
if (dd->read_ahead.trigger == block
if (bdbuf_cache.read_ahead_task != 0
&& dd->read_ahead.trigger == block
&& !rtems_bdbuf_is_read_ahead_active (dd))
{
rtems_status_code sc;
rtems_chain_control *chain = &bdbuf_cache.read_ahead_chain;
if (rtems_chain_is_empty (chain))
{
sc = rtems_event_send (bdbuf_cache.read_ahead_task,
RTEMS_BDBUF_READ_AHEAD_WAKE_UP);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_RA_WAKE_UP);
}
rtems_chain_append_unprotected (chain, &dd->read_ahead.node);
sc = rtems_event_send (bdbuf_cache.read_ahead_task,
RTEMS_BDBUF_READ_AHEAD_WAKE_UP);
if (sc != RTEMS_SUCCESSFUL)
rtems_fatal_error_occurred (RTEMS_BLKDEV_FATAL_BDBUF_RA_WAKE_UP);
}
}