X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=ipc.c;h=2cab393700dfbf84a8119228f49a21e705174278;hp=973a9eaf4ffee1e69eb5a5e5460f7060f654b433;hb=5b972aabaf27931cae6ac318c9b920d33593f07b;hpb=746589429fb545c096837fe59c9d9199f01070a1

diff --git a/ipc.c b/ipc.c
index 973a9eaf..2cab3937 100644
--- a/ipc.c
+++ b/ipc.c
@@ -1,17 +1,41 @@
+/*
+ * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
+ *
+ * Licensed under the GPL v2. For licencing details see COPYING.
+ */
+
+/** \file ipc.c interprocess communication and shared memory helpers */
+
 #include "para.h"
 #include "error.h"
 #include "ipc.h"
 #include <sys/ipc.h>
 #include <sys/shm.h>
+#include <sys/sem.h>
 
-#define MAX_SEMOP_RETRIES 500
-
+/**
+ * define a new mutex
+ *
+ * \return the identifier for the new mutex on success, \a -E_SEM_GET
+ * on errors.
+ *
+ * \sa semget(2)
+ */
 int mutex_new(void)
 {
 	int ret = semget(IPC_PRIVATE, 1, IPC_CREAT | 0666);
 	return ret < 0?  -E_SEM_GET : ret;
 }
 
+/**
+ * destroy a mutex
+ *
+ * \param id the identifier of the mutex to be destroyed
+ *
+ * \return Positive on success, \a -E_SEM_REMOVE on errors.
+ *
+ * \sa semctl(2)
+ */
 int mutex_destroy(int id)
 {
 	int ret = semctl(id, 0, IPC_RMID);
@@ -20,18 +44,26 @@ int mutex_destroy(int id)
 
 static void para_semop(int id, struct sembuf *sops, int num)
 {
-	int i;
-
-	for (i = 0; i < MAX_SEMOP_RETRIES; i++)
+	do {
 		if (semop(id, sops, num) >= 0)
 			return;
-	PARA_EMERG_LOG("semop failed %d times, aborting\n", MAX_SEMOP_RETRIES);
+	} while (errno == EINTR);
+	if (errno == EIDRM) {
+		PARA_NOTICE_LOG("semaphore set %d was removed\n", id);
+		return;
+	}
+	PARA_EMERG_LOG("fatal semop error %s: pid %d\n", strerror(errno),
+		(int)getpid());
 	exit(EXIT_FAILURE);
 }
 
 /**
  * lock the given mutex
  *
+ * \param id of the shared memory area to lock
+ *
+ * This function either succeeds or aborts.
+ *
  * \sa semop(2), struct misc_meta_data
  */
 void mutex_lock(int id)
@@ -54,6 +86,10 @@ void mutex_lock(int id)
 /**
  * unlock a mutex
  *
+ * \param id the identifier of the mutex
+ *
+ * This function either succeeds or aborts.
+ *
  * \sa semop(2), struct misc_meta_data
  */
 void mutex_unlock(int id)
@@ -70,7 +106,11 @@ void mutex_unlock(int id)
 
 /**
  * create a new shared memory area of given size
- * 
+ *
+ * \param size the size of the shared memory area to create
+ *
+ * \return The id of the shared memory areay on success, \a -E_SHM_GET on errors.
+ *
  * \sa shmget(2)
  */
 int shm_new(size_t size)
@@ -81,8 +121,14 @@ int shm_new(size_t size)
 
 /**
  * destroy the given shared memory area
+ *
+ * \param id the shared memory id
+ *
+ * \return The return value of the underlying shmctl() call on success,
+ * \a -E_SHM_DESTROY on errors.
+ *
  * \sa shmctl(2)
- **/
+ */
 int shm_destroy(int id)
 {
 	struct shmid_ds shm_desc;
@@ -91,9 +137,15 @@ int shm_destroy(int id)
 }
 
 /**
- * attach a shared memory area
+ * attach a shared memory segment
+ *
+ * \param id the identifier of the shared memory segment to attach
+ * \param mode either ATTACH_RO (read only) or ATTACH_RW (read/write)
+ * \param result points to the attached area just attached
  *
- * \sa semop(2)
+ * \return positive on success, \a -E_SHM_ATTACH on errors.
+ *
+ * \sa shmat(2)
  */
 int shm_attach(int id, enum shm_attach_mode mode, void **result)
 {
@@ -105,6 +157,15 @@ int shm_attach(int id, enum shm_attach_mode mode, void **result)
 	return *result? 1 : -E_SHM_ATTACH;
 }
 
+/**
+ * detach a shared memory segment
+ *
+ * \param addr the address of the attached segment
+ *
+ * \return positive on success, \a -E_SHM_DETACH on errors.
+ *
+ * \sa shmdt(2)
+ */
 int shm_detach(void *addr)
 {
 	int ret = shmdt(addr);