6a3c2aded6
* Simplify EINTR/ECANCEL error handling 1. Add semaphore uninterruptible wait function 2 .Replace semaphore wait loop with a single uninterruptible wait 3. Replace all sem_xxx to nxsem_xxx * Unify the void cast usage 1. Remove void cast for function because many place ignore the returned value witout cast 2. Replace void cast for variable with UNUSED macro
310 lines
9.8 KiB
C
310 lines
9.8 KiB
C
/****************************************************************************
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* mm/iob/iob_alloc.c
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*
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* Copyright (C) 2014, 2016-2017 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <semaphore.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/sched.h>
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#include <nuttx/mm/iob.h>
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#include "iob.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: iob_alloc_committed
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*
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* Description:
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* Allocate an I/O buffer by taking the buffer at the head of the committed
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* list.
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*
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****************************************************************************/
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static FAR struct iob_s *iob_alloc_committed(enum iob_user_e consumerid)
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{
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FAR struct iob_s *iob = NULL;
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irqstate_t flags;
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/* We don't know what context we are called from so we use extreme measures
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* to protect the committed list: We disable interrupts very briefly.
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*/
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flags = enter_critical_section();
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/* Take the I/O buffer from the head of the committed list */
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iob = g_iob_committed;
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if (iob != NULL)
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{
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/* Remove the I/O buffer from the committed list */
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g_iob_committed = iob->io_flink;
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/* Put the I/O buffer in a known state */
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iob->io_flink = NULL; /* Not in a chain */
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iob->io_len = 0; /* Length of the data in the entry */
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iob->io_offset = 0; /* Offset to the beginning of data */
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iob->io_pktlen = 0; /* Total length of the packet */
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#if !defined(CONFIG_DISABLE_MOUNTPOINT) && defined(CONFIG_FS_PROCFS) && \
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defined(CONFIG_MM_IOB) && !defined(CONFIG_FS_PROCFS_EXCLUDE_IOBINFO)
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iob_stats_onalloc(consumerid);
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#endif
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}
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leave_critical_section(flags);
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return iob;
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}
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/****************************************************************************
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* Name: iob_allocwait
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*
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* Description:
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* Allocate an I/O buffer, waiting if necessary. This function cannot be
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* called from any interrupt level logic.
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*
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****************************************************************************/
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static FAR struct iob_s *iob_allocwait(bool throttled,
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enum iob_user_e consumerid)
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{
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FAR struct iob_s *iob;
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irqstate_t flags;
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FAR sem_t *sem;
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int ret = OK;
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#if CONFIG_IOB_THROTTLE > 0
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/* Select the semaphore count to check. */
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sem = (throttled ? &g_throttle_sem : &g_iob_sem);
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#else
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sem = &g_iob_sem;
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#endif
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/* The following must be atomic; interrupt must be disabled so that there
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* is no conflict with interrupt level I/O buffer allocations. This is
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* not as bad as it sounds because interrupts will be re-enabled while
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* we are waiting for I/O buffers to become free.
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*/
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flags = enter_critical_section();
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/* Try to get an I/O buffer. If successful, the semaphore count will be
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* decremented atomically.
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*/
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iob = iob_tryalloc(throttled, consumerid);
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while (ret == OK && iob == NULL)
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{
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/* If not successful, then the semaphore count was less than or equal
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* to zero (meaning that there are no free buffers). We need to wait
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* for an I/O buffer to be released and placed in the committed
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* list.
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*/
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ret = nxsem_wait_uninterruptible(sem);
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if (ret >= 0)
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{
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/* When we wake up from wait successfully, an I/O buffer was
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* freed and we hold a count for one IOB.
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*/
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iob = iob_alloc_committed(consumerid);
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if (iob == NULL)
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{
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/* We need release our count so that it is available to
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* iob_tryalloc(), perhaps allowing another thread to take our
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* count. In that event, iob_tryalloc() will fail above and
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* we will have to wait again.
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*/
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nxsem_post(sem);
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iob = iob_tryalloc(throttled, consumerid);
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}
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/* REVISIT: I think this logic should be moved inside of
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* iob_alloc_committed, so that it can exist inside of the critical
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* section along with all other sem count changes.
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*/
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#if CONFIG_IOB_THROTTLE > 0
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else
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{
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if (throttled)
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{
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g_iob_sem.semcount--;
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}
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else
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{
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g_throttle_sem.semcount--;
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}
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}
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#endif
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}
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}
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leave_critical_section(flags);
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return iob;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: iob_alloc
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*
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* Description:
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* Allocate an I/O buffer by taking the buffer at the head of the free list.
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*
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****************************************************************************/
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FAR struct iob_s *iob_alloc(bool throttled, enum iob_user_e consumerid)
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{
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/* Were we called from the interrupt level? */
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if (up_interrupt_context() || sched_idletask())
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{
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/* Yes, then try to allocate an I/O buffer without waiting */
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return iob_tryalloc(throttled, consumerid);
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}
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else
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{
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/* Then allocate an I/O buffer, waiting as necessary */
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return iob_allocwait(throttled, consumerid);
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}
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}
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/****************************************************************************
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* Name: iob_tryalloc
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*
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* Description:
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* Try to allocate an I/O buffer by taking the buffer at the head of the
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* free list without waiting for a buffer to become free.
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*
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****************************************************************************/
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FAR struct iob_s *iob_tryalloc(bool throttled, enum iob_user_e consumerid)
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{
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FAR struct iob_s *iob;
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irqstate_t flags;
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#if CONFIG_IOB_THROTTLE > 0
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FAR sem_t *sem;
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#endif
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#if CONFIG_IOB_THROTTLE > 0
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/* Select the semaphore count to check. */
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sem = (throttled ? &g_throttle_sem : &g_iob_sem);
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#endif
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/* We don't know what context we are called from so we use extreme measures
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* to protect the free list: We disable interrupts very briefly.
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*/
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flags = enter_critical_section();
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#if CONFIG_IOB_THROTTLE > 0
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/* If there are free I/O buffers for this allocation */
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if (sem->semcount > 0)
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#endif
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{
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/* Take the I/O buffer from the head of the free list */
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iob = g_iob_freelist;
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if (iob != NULL)
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{
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/* Remove the I/O buffer from the free list and decrement the
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* counting semaphore(s) that tracks the number of available
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* IOBs.
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*/
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g_iob_freelist = iob->io_flink;
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/* Take a semaphore count. Note that we cannot do this in
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* in the orthodox way by calling nxsem_wait() or nxsem_trywait()
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* because this function may be called from an interrupt
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* handler. Fortunately we know at at least one free buffer
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* so a simple decrement is all that is needed.
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*/
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g_iob_sem.semcount--;
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DEBUGASSERT(g_iob_sem.semcount >= 0);
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#if CONFIG_IOB_THROTTLE > 0
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/* The throttle semaphore is a little more complicated because
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* it can be negative! Decrementing is still safe, however.
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*/
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g_throttle_sem.semcount--;
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DEBUGASSERT(g_throttle_sem.semcount >= -CONFIG_IOB_THROTTLE);
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#endif
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#if !defined(CONFIG_DISABLE_MOUNTPOINT) && defined(CONFIG_FS_PROCFS) && \
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defined(CONFIG_MM_IOB) && !defined(CONFIG_FS_PROCFS_EXCLUDE_IOBINFO)
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iob_stats_onalloc(consumerid);
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#endif
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leave_critical_section(flags);
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/* Put the I/O buffer in a known state */
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iob->io_flink = NULL; /* Not in a chain */
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iob->io_len = 0; /* Length of the data in the entry */
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iob->io_offset = 0; /* Offset to the beginning of data */
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iob->io_pktlen = 0; /* Total length of the packet */
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return iob;
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}
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}
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leave_critical_section(flags);
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return NULL;
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}
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