diff options
Diffstat (limited to 'nuttx/net/uip/uip_lock.c')
-rw-r--r-- | nuttx/net/uip/uip_lock.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/nuttx/net/uip/uip_lock.c b/nuttx/net/uip/uip_lock.c new file mode 100644 index 000000000..0e770cef7 --- /dev/null +++ b/nuttx/net/uip/uip_lock.c @@ -0,0 +1,218 @@ +/**************************************************************************** + * net/uip/uip_lock.c + * + * Copyright (C) 2011-2012 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <semaphore.h> +#include <assert.h> +#include <errno.h> +#include <debug.h> + +#include <nuttx/arch.h> +#include <nuttx/net/uip/uip.h> + +#if defined(CONFIG_NET) && defined(CONFIG_NET_NOINTS) + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +#define NO_HOLDER (pid_t)-1 + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +static sem_t g_uipsem; +static pid_t g_holder = NO_HOLDER; +static unsigned int g_count = 0; + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Function: uip_takesem + * + * Description: + * Take the semaphore + * + ****************************************************************************/ + +static void uip_takesem(void) +{ + while (sem_wait(&g_uipsem) != 0) + { + /* The only case that an error should occur here is if the wait was + * awakened by a signal. + */ + + ASSERT(errno == EINTR); + } +} + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Function: uip_lockinit + * + * Description: + * Initialize the locking facility + * + ****************************************************************************/ + +void uip_lockinit(void) +{ + sem_init(&g_uipsem, 0, 1); +} + +/**************************************************************************** + * Function: uip_lock + * + * Description: + * Take the lock + * + ****************************************************************************/ + +uip_lock_t uip_lock(void) +{ + pid_t me = getpid(); + + /* Does this thread already hold the semaphore? */ + + if (g_holder == me) + { + /* Yes.. just increment the reference count */ + + g_count++; + } + else + { + /* No.. take the semaphore (perhaps waiting) */ + + uip_takesem(); + + /* Now this thread holds the semaphore */ + + g_holder = me; + g_count = 1; + } + + return 0; +} + +/**************************************************************************** + * Function: uip_unlock + * + * Description: + * Release the lock. + * + ****************************************************************************/ + +void uip_unlock(uip_lock_t flags) +{ + DEBUGASSERT(g_holder == getpid() && g_count > 0); + + /* If the count would go to zero, then release the semaphore */ + + if (g_count == 1) + { + /* We no longer hold the semaphore */ + + g_holder = NO_HOLDER; + g_count = 0; + sem_post(&g_uipsem); + } + else + { + /* We still hold the semaphore. Just decrement the count */ + + g_count--; + } +} + +/**************************************************************************** + * Function: uip_lockedwait + * + * Description: + * Atomically wait for sem while temporarily releasing g_uipsem. + * + ****************************************************************************/ + +int uip_lockedwait(sem_t *sem) +{ + pid_t me = getpid(); + unsigned int count; + irqstate_t flags; + int ret; + + flags = irqsave(); /* No interrupts */ + sched_lock(); /* No context switches */ + if (g_holder == me) + { + /* Release the uIP semaphore, remembering the count */ + + count = g_count; + g_holder = NO_HOLDER; + g_count = 0; + sem_post(&g_uipsem); + + /* Now take the semaphore */ + + ret = sem_wait(sem); + + /* Recover the uIP semaphore at the proper count */ + + uip_takesem(); + g_holder = me; + g_count = count; + } + else + { + ret = sem_wait(sem); + } + + sched_unlock(); + irqrestore(flags); + return ret; + } + +#endif /* CONFIG_NET */ |