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drivers/serial/serial.c: Limit the number of times that the poll semaphore is incrmented.

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This commit is contained in:
Dave Marples
2019-06-13 16:22:41 -06:00
committed by Gregory Nutt
parent 81e17306d1
commit 5179fa9a64
4 changed files with 173 additions and 7 deletions
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drivers/serial/serial.c
+19 -2
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@@ -1,7 +1,8 @@
/************************************************************************************
* drivers/serial/serial.c
*
* Copyright (C) 2007-2009, 2011-2013, 2016-2018 Gregory Nutt. All rights reserved.
* Copyright (C) 2007-2009, 2011-2013, 2016-2019 Gregory Nutt. All rights
* reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@@ -195,8 +196,24 @@ static void uart_pollnotify(FAR uart_dev_t *dev, pollevent_t eventset)
#endif
if (fds->revents != 0)
{
irqstate_t flags;
int semcount;
finfo("Report events: %02x\n", fds->revents);
nxsem_post(fds->sem);
/* Limit the number of times that the semaphore is posted.
* The critical section is needed to make the following
* operation atomic.
*/
flags = enter_critical_section();
nxsem_getvalue(fds->sem, &semcount);
if (semcount < 1)
{
nxsem_post(fds->sem);
}
leave_critical_section(flags);
}
}
}