ipc/sem.c: convert undo structures to struct list_head
The undo structures contain two linked lists, the attached patch replaces them with generic struct list_head lists. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Nadia Derbey <Nadia.Derbey@bull.net> Cc: Pierre Peiffer <peifferp@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Manfred Spraul
Linus Torvalds
Родитель
00c2bf85d8
Коммит
4daa28f6d8
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@ -95,7 +95,7 @@ struct sem_array {
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struct sem *sem_base; /* ptr to first semaphore in array */
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struct sem_queue *sem_pending; /* pending operations to be processed */
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struct sem_queue **sem_pending_last; /* last pending operation */
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struct sem_undo *undo; /* undo requests on this array */
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struct list_head list_id; /* undo requests on this array */
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unsigned long sem_nsems; /* no. of semaphores in array */
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};
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@ -118,8 +118,8 @@ struct sem_queue {
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* when the process exits.
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*/
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struct sem_undo {
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struct sem_undo * proc_next; /* next entry on this process */
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struct sem_undo * id_next; /* next entry on this semaphore set */
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struct list_head list_proc; /* per-process list: all undos from one process */
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struct list_head list_id; /* per semaphore array list: all undos for one array */
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int semid; /* semaphore set identifier */
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short * semadj; /* array of adjustments, one per semaphore */
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};
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@ -128,9 +128,9 @@ struct sem_undo {
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* that may be shared among all a CLONE_SYSVSEM task group.
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*/
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struct sem_undo_list {
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atomic_t refcnt;
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spinlock_t lock;
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struct sem_undo *proc_list;
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atomic_t refcnt;
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spinlock_t lock;
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struct list_head list_proc;
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};
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struct sysv_sem {
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159
ipc/sem.c
159
ipc/sem.c
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@ -274,7 +274,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
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sma->sem_base = (struct sem *) &sma[1];
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/* sma->sem_pending = NULL; */
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sma->sem_pending_last = &sma->sem_pending;
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/* sma->undo = NULL; */
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INIT_LIST_HEAD(&sma->list_id);
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sma->sem_nsems = nsems;
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sma->sem_ctime = get_seconds();
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sem_unlock(sma);
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@ -536,7 +536,8 @@ static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
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* (They will be freed without any further action in exit_sem()
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* or during the next semop.)
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*/
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for (un = sma->undo; un; un = un->id_next)
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assert_spin_locked(&sma->sem_perm.lock);
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list_for_each_entry(un, &sma->list_id, list_id)
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un->semid = -1;
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/* Wake up all pending processes and let them fail with EIDRM. */
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@ -763,9 +764,12 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
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for (i = 0; i < nsems; i++)
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sma->sem_base[i].semval = sem_io[i];
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for (un = sma->undo; un; un = un->id_next)
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assert_spin_locked(&sma->sem_perm.lock);
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list_for_each_entry(un, &sma->list_id, list_id) {
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for (i = 0; i < nsems; i++)
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un->semadj[i] = 0;
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}
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sma->sem_ctime = get_seconds();
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/* maybe some queued-up processes were waiting for this */
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update_queue(sma);
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@ -797,12 +801,15 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
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{
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int val = arg.val;
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struct sem_undo *un;
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err = -ERANGE;
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if (val > SEMVMX || val < 0)
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goto out_unlock;
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for (un = sma->undo; un; un = un->id_next)
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assert_spin_locked(&sma->sem_perm.lock);
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list_for_each_entry(un, &sma->list_id, list_id)
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un->semadj[semnum] = 0;
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curr->semval = val;
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curr->sempid = task_tgid_vnr(current);
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sma->sem_ctime = get_seconds();
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@ -952,6 +959,8 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp)
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return -ENOMEM;
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spin_lock_init(&undo_list->lock);
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atomic_set(&undo_list->refcnt, 1);
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INIT_LIST_HEAD(&undo_list->list_proc);
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current->sysvsem.undo_list = undo_list;
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}
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*undo_listp = undo_list;
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@ -960,25 +969,30 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp)
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static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
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{
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struct sem_undo **last, *un;
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struct sem_undo *walk, *tmp;
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last = &ulp->proc_list;
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un = *last;
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while(un != NULL) {
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if(un->semid==semid)
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break;
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if(un->semid==-1) {
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*last=un->proc_next;
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kfree(un);
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} else {
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last=&un->proc_next;
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assert_spin_locked(&ulp->lock);
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list_for_each_entry_safe(walk, tmp, &ulp->list_proc, list_proc) {
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if (walk->semid == semid)
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return walk;
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if (walk->semid == -1) {
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list_del(&walk->list_proc);
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kfree(walk);
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}
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un=*last;
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}
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return un;
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return NULL;
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}
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static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
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/**
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* find_alloc_undo - Lookup (and if not present create) undo array
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* @ns: namespace
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* @semid: semaphore array id
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*
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* The function looks up (and if not present creates) the undo structure.
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* The size of the undo structure depends on the size of the semaphore
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* array, thus the alloc path is not that straightforward.
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*/
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static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
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{
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struct sem_array *sma;
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struct sem_undo_list *ulp;
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@ -997,6 +1011,7 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
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goto out;
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/* no undo structure around - allocate one. */
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/* step 1: figure out the size of the semaphore array */
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sma = sem_lock_check(ns, semid);
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if (IS_ERR(sma))
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return ERR_PTR(PTR_ERR(sma));
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@ -1004,15 +1019,19 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
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nsems = sma->sem_nsems;
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sem_getref_and_unlock(sma);
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/* step 2: allocate new undo structure */
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new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
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if (!new) {
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sem_putref(sma);
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return ERR_PTR(-ENOMEM);
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}
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new->semadj = (short *) &new[1];
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new->semid = semid;
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/* step 3: Acquire the lock on the undo list pointer */
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spin_lock(&ulp->lock);
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/* step 4: check for races: someone else allocated the undo struct,
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* semaphore array was destroyed.
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*/
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un = lookup_undo(ulp, semid);
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if (un) {
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spin_unlock(&ulp->lock);
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@ -1028,13 +1047,17 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
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un = ERR_PTR(-EIDRM);
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goto out;
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}
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new->proc_next = ulp->proc_list;
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ulp->proc_list = new;
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new->id_next = sma->undo;
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sma->undo = new;
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/* step 5: initialize & link new undo structure */
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new->semadj = (short *) &new[1];
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new->semid = semid;
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assert_spin_locked(&ulp->lock);
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list_add(&new->list_proc, &ulp->list_proc);
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assert_spin_locked(&sma->sem_perm.lock);
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list_add(&new->list_id, &sma->list_id);
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sem_unlock(sma);
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un = new;
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spin_unlock(&ulp->lock);
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un = new;
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out:
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return un;
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}
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@ -1090,9 +1113,8 @@ asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops,
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alter = 1;
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}
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retry_undos:
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if (undos) {
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un = find_undo(ns, semid);
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un = find_alloc_undo(ns, semid);
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if (IS_ERR(un)) {
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error = PTR_ERR(un);
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goto out_free;
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@ -1107,14 +1129,14 @@ retry_undos:
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}
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/*
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* semid identifiers are not unique - find_undo may have
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* semid identifiers are not unique - find_alloc_undo may have
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* allocated an undo structure, it was invalidated by an RMID
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* and now a new array with received the same id. Check and retry.
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* and now a new array with received the same id. Check and fail.
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*/
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if (un && un->semid == -1) {
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sem_unlock(sma);
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goto retry_undos;
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}
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error = -EIDRM;
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if (un && un->semid == -1)
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goto out_unlock_free;
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error = -EFBIG;
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if (max >= sma->sem_nsems)
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goto out_unlock_free;
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@ -1243,56 +1265,44 @@ int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
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*/
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void exit_sem(struct task_struct *tsk)
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{
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struct sem_undo_list *undo_list;
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struct sem_undo *u, **up;
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struct ipc_namespace *ns;
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struct sem_undo_list *ulp;
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struct sem_undo *un, *tmp;
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undo_list = tsk->sysvsem.undo_list;
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if (!undo_list)
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ulp = tsk->sysvsem.undo_list;
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if (!ulp)
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return;
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tsk->sysvsem.undo_list = NULL;
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if (!atomic_dec_and_test(&undo_list->refcnt))
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if (!atomic_dec_and_test(&ulp->refcnt))
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return;
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ns = tsk->nsproxy->ipc_ns;
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/* There's no need to hold the semundo list lock, as current
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* is the last task exiting for this undo list.
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*/
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for (up = &undo_list->proc_list; (u = *up); *up = u->proc_next, kfree(u)) {
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spin_lock(&ulp->lock);
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list_for_each_entry_safe(un, tmp, &ulp->list_proc, list_proc) {
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struct sem_array *sma;
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int nsems, i;
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struct sem_undo *un, **unp;
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int semid;
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semid = u->semid;
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int i;
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if(semid == -1)
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continue;
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sma = sem_lock(ns, semid);
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if (un->semid == -1)
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goto free;
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sma = sem_lock(tsk->nsproxy->ipc_ns, un->semid);
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if (IS_ERR(sma))
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continue;
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goto free;
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if (u->semid == -1)
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goto next_entry;
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if (un->semid == -1)
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goto unlock_free;
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BUG_ON(sem_checkid(sma, u->semid));
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BUG_ON(sem_checkid(sma, un->semid));
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/* remove u from the sma->undo list */
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for (unp = &sma->undo; (un = *unp); unp = &un->id_next) {
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if (u == un)
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goto found;
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}
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printk ("exit_sem undo list error id=%d\n", u->semid);
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goto next_entry;
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found:
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*unp = un->id_next;
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/* perform adjustments registered in u */
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nsems = sma->sem_nsems;
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for (i = 0; i < nsems; i++) {
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/* remove un from sma->list_id */
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assert_spin_locked(&sma->sem_perm.lock);
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list_del(&un->list_id);
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/* perform adjustments registered in un */
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for (i = 0; i < sma->sem_nsems; i++) {
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struct sem * semaphore = &sma->sem_base[i];
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if (u->semadj[i]) {
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semaphore->semval += u->semadj[i];
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if (un->semadj[i]) {
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semaphore->semval += un->semadj[i];
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/*
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* Range checks of the new semaphore value,
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* not defined by sus:
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@ -1316,10 +1326,15 @@ found:
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sma->sem_otime = get_seconds();
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/* maybe some queued-up processes were waiting for this */
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update_queue(sma);
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next_entry:
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unlock_free:
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sem_unlock(sma);
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free:
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assert_spin_locked(&ulp->lock);
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list_del(&un->list_proc);
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kfree(un);
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}
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kfree(undo_list);
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spin_unlock(&ulp->lock);
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kfree(ulp);
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}
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#ifdef CONFIG_PROC_FS
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