diff options
Diffstat (limited to 'nuttx/binfmt/binfmt_schedunload.c')
| -rw-r--r-- | nuttx/binfmt/binfmt_schedunload.c | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/nuttx/binfmt/binfmt_schedunload.c b/nuttx/binfmt/binfmt_schedunload.c new file mode 100644 index 000000000..972d17963 --- /dev/null +++ b/nuttx/binfmt/binfmt_schedunload.c @@ -0,0 +1,333 @@ +/**************************************************************************** + * binfmt/binfmt_schedunload.c + * + * Copyright (C) 2013 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 <sched.h> +#include <debug.h> +#include <errno.h> + +#include <nuttx/kmalloc.h> +#include <nuttx/binfmt/binfmt.h> + +#include "binfmt_internal.h" + +#if !defined(CONFIG_BINFMT_DISABLE) && defined(CONFIG_SCHED_HAVE_PARENT) + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/**************************************************************************** + * Private Function Prototypes + ****************************************************************************/ + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +FAR struct binary_s *g_unloadhead; + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: unload_list_add + * + * Description: + * If CONFIG_SCHED_HAVE_PARENT is defined then schedul_unload() will + * manage instances of struct binary_s allocated with kmalloc. It + * will keep the binary data in a link list and when SIGCHLD is received + * (meaning that the task has exit'ed, schedul_unload() will find the + * data, unload the module, and free the structure. + * + * This function will add one structure to the linked list + * + * Input Parameter: + * pid - The task ID of the child task + * bin - This structure must have been allocated with kmalloc() and must + * persist until the task unloads + + * + * Returned Value: + * None + * + ****************************************************************************/ + +static void unload_list_add(pid_t pid, FAR struct binary_s *bin) +{ + irqstate_t flags; + + /* Save the PID in the structure so that we recover it later */ + + bin->pid = pid; + + /* Disable deliver of any signals while we muck with the list. The graceful + * way to do this would be block delivery of SIGCHLD would be with + * sigprocmask. Here we do it the quick'n'dirty way by just disabling + * interrupts. + */ + + flags = irqsave(); + bin->flink = g_unloadhead; + g_unloadhead = bin; + irqrestore(flags); +} + +/**************************************************************************** + * Name: unload_list_remove + * + * Description: + * If CONFIG_SCHED_HAVE_PARENT is defined then schedul_unload() will + * manage instances of struct binary_s allocated with kmalloc. It + * will keep the binary data in a link list and when SIGCHLD is received + * (meaning that the task has exit'ed, schedul_unload() will find the + * data, unload the module, and free the structure. + * + * This function will remove one structure to the linked list + * + * Input Parameter: + * pid - The task ID of the child task + * + * Returned Value: + * On success, the load structure is returned. NULL is returned on + * failure. + * + ****************************************************************************/ + +static FAR struct binary_s *unload_list_remove(pid_t pid) +{ + FAR struct binary_s *curr; + FAR struct binary_s *prev; + + /* Note the asymmetry. We do not have to disable interrupts here because + * the main thread cannot run while we are in the interrupt handler. Here, + * it should be sufficient to disable pre-emption so that no other thread + * can run. + */ + + sched_lock(); + + /* Find the structure in the unload list with the matching PID */ + + for (prev = NULL, curr = g_unloadhead; + curr && (curr->pid != pid); + prev = curr, curr = curr->flink); + + /* Did we find it? It must be there. Hmmm.. we should probably ASSERT if + * we do not! + */ + + if (curr) + { + /* Was there another entry before this one? */ + + if (prev) + { + /* Yes.. remove the current entry from after the previous entry */ + + prev->flink = curr->flink; + } + else + { + /* No.. remove the current entry from the head of the list */ + + g_unloadhead = curr->flink; + } + + /* Nullify the forward link ... superstitious */ + + curr->flink = NULL; + } + + sched_unlock(); + return curr; +} + +/**************************************************************************** + * Name: unload_callback + * + * Description: + * If CONFIG_SCHED_HAVE_PARENT is defined, this function may be called to + * automatically unload the module when task exits. It assumes that + * bin was allocated with kmalloc() or friends and will also automatically + * free the structure with kfree() when the task exists. + * + * Input Parameter: + * pid - The ID of the task that just exited + * arg - A reference to the load structure cast to FAR void * + * + * Returned Value: + * None + * + ****************************************************************************/ + +static void unload_callback(int signo, siginfo_t *info, void *ucontext) +{ + FAR struct binary_s *bin; + int ret; + + /* Sanity checking */ + + if (!info || signo != SIGCHLD) + { + blldbg("ERROR:Bad signal callback: signo=%d info=%p\n", signo, callback); + return; + } + + /* Get the load information for this pid */ + + bin = unload_list_remove(info->si_pid); + if (!bin) + { + blldbg("ERROR: Could not find load info for PID=%d\n", info->si_pid); + return; + } + + /* Unload the module */ + + ret = unload_module(bin); + if (ret < 0) + { + blldbg("ERROR: unload_module failed: %d\n", get_errno()); + } + + /* Free the load structure */ + + kfree(bin); +} + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: schedule_unload + * + * Description: + * If CONFIG_SCHED_HAVE_PARENT is defined, this function may be called by + * the parent of the the newly created task to automatically unload the + * module when the task exits. This assumes that (1) the caller is the + * parent of the created task, (2) that bin was allocated with kmalloc() + * or friends. It will also automatically free the structure with kfree() + * after unloading the module. + * + * Input Parameter: + * pid - The task ID of the child task + * bin - This structure must have been allocated with kmalloc() and must + * persist until the task unloads + * + * Returned Value: + * This is an end-user function, so it follows the normal convention: + * It returns 0 (OK) if the callback was successfully scheduled. On + * failure, it returns -1 (ERROR) and sets errno appropriately. + * + * On failures, the 'bin' structure will not be deallocated and the + * module not not be unloaded. + * + ****************************************************************************/ + +int schedule_unload(pid_t pid, FAR struct binary_s *bin) +{ + struct sigaction act; + struct sigaction oact; + sigset_t sigset; + irqstate_t flags; + int errorcode; + int ret; + + /* Make sure that SIGCHLD is unmasked */ + + (void)sigemptyset(&sigset); + (void)sigaddset(&sigset, SIGCHLD); + ret = sigprocmask(SIG_UNBLOCK, &sigset, NULL); + if (ret != OK) + { + /* The errno value will get trashed by the following debug output */ + + errorcode = get_errno(); + bvdbg("ERROR: sigprocmask failed: %d\n", ret); + goto errout; + } + + /* Add the structure to the list. We want to do this *before* connecting + * the signal handler. This does, however, make error recovery more + * complex if sigaction() fails below because then we have to remove the + * unload structure for the list in an unexpected context. + */ + + unload_list_add(pid, bin); + + /* Register the SIGCHLD handler */ + + act.sa_sigaction = unload_callback; + act.sa_flags = SA_SIGINFO; + + (void)sigfillset(&act.sa_mask); + (void)sigdelset(&act.sa_mask, SIGCHLD); + + ret = sigaction(SIGCHLD, &act, &oact); + if (ret != OK) + { + /* The errno value will get trashed by the following debug output */ + + errorcode = get_errno(); + bvdbg("ERROR: sigaction failed: %d\n" , ret); + + /* Emergency removal from the list */ + + flags = irqsave(); + if (unload_list_remove(pid) != bin) + { + blldbg("ERROR: Failed to remove structure\n"); + } + + goto errout; + } + + return OK; + +errout: + set_errno(errorcode); + return ERROR; +} + +#endif /* !CONFIG_BINFMT_DISABLE && CONFIG_SCHED_HAVE_PARENT */ + |