diff options
Diffstat (limited to 'nuttx/sched/sig_suspend.c')
| -rw-r--r-- | nuttx/sched/sig_suspend.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/nuttx/sched/sig_suspend.c b/nuttx/sched/sig_suspend.c new file mode 100644 index 000000000..09f47dee9 --- /dev/null +++ b/nuttx/sched/sig_suspend.c @@ -0,0 +1,180 @@ +/**************************************************************************** + * sched/sig_suspend.c + * + * Copyright (C) 2007-2009 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 <signal.h> +#include <assert.h> +#include <debug.h> +#include <sched.h> + +#include <nuttx/arch.h> + +#include "os_internal.h" +#include "sig_internal.h" + +/**************************************************************************** + * Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Type Declarations + ****************************************************************************/ + +/**************************************************************************** + * Global Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Variables + ****************************************************************************/ + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: sigsuspend + * + * Description: + * + * The sigsuspend() function replaces the signal mask of the task with the + * set of signals pointed to by the argument 'set' and then suspends the + * process until delivery of a signal to the task. + * + * If the effect of the set argument is to unblock a pending signal, then + * no wait is performed. + * + * The original signal mask is restored when this function returns. + * + * Waiting for an empty signal set stops a task without freeing any + * resources. + * + * Parameters: + * set - signal mask to use while suspended. + * + * Return Value: + * -1 (ERROR) always + * + * Assumptions: + * + * POSIX Compatibility: + * int sigsuspend(const sigset_t *set); + * + * POSIX states that sigsuspend() "suspends the process until delivery of + * a signal whose action is either to execute a signal-catching function + * or to terminate the process." Only the deliver of a signal is required + * in the present implementation (even if the signal is ignored). + * + ****************************************************************************/ + +int sigsuspend(FAR const sigset_t *set) +{ + FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head; + sigset_t intersection; + sigset_t saved_sigprocmask; + FAR sigpendq_t *sigpend; + irqstate_t saved_state; + int unblocksigno; + + /* Several operations must be performed below: We must determine if any + * signal is pending and, if not, wait for the signal. Since signals can + * be posted from the interrupt level, there is a race condition that + * can only be eliminated by disabling interrupts! + */ + + sched_lock(); /* Not necessary */ + saved_state = irqsave(); + + /* Check if there is a pending signal corresponding to one of the + * signals that will be unblocked by the new sigprocmask. + */ + + intersection = ~(*set) & sig_pendingset(rtcb); + if (intersection != NULL_SIGNAL_SET) + { + /* One or more of the signals in intersections is sufficient to cause + * us to not wait. Pick the lowest numbered signal and mark it not + * pending. + */ + + unblocksigno = sig_lowest(&intersection); + sigpend = sig_removependingsignal(rtcb, unblocksigno); + if (!sigpend) + { + PANIC(OSERR_FAILEDTOREMOVESIGNAL); + } + + sig_releasependingsignal(sigpend); + irqrestore(saved_state); + } + else + { + /* Its time to wait. Save a copy of the old sigprocmask and install + * the new (temporary) sigprocmask + */ + + saved_sigprocmask = rtcb->sigprocmask; + rtcb->sigprocmask = *set; + rtcb->sigwaitmask = NULL_SIGNAL_SET; + + /* And wait until one of the unblocked signals is posted */ + + up_block_task(rtcb, TSTATE_WAIT_SIG); + + /* We are running again, restore the original sigprocmask */ + + rtcb->sigprocmask = saved_sigprocmask; + irqrestore(saved_state); + + /* Now, handle the (rare?) case where (a) a blocked signal was received + * while the task was suspended but (b) restoring the original + * sigprocmask will unblock the signal. + */ + + sig_unmaskpendingsignal(); + } + + sched_unlock(); + return ERROR; +} |