#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid)
-#define sem_buildid(id, seq) ipc_buildid(id, seq)
static int newary(struct ipc_namespace *, struct ipc_params *);
static void freeary(struct ipc_namespace *, struct kern_ipc_perm *);
IPC_SEM_IDS, sysvipc_sem_proc_show);
}
-/*
- * This routine is called in the paths where the rw_mutex is held to protect
- * access to the idr tree.
- */
-static inline struct sem_array *sem_lock_check_down(struct ipc_namespace *ns,
- int id)
-{
- struct kern_ipc_perm *ipcp = ipc_lock_check_down(&sem_ids(ns), id);
-
- if (IS_ERR(ipcp))
- return (struct sem_array *)ipcp;
-
- return container_of(ipcp, struct sem_array, sem_perm);
-}
-
/*
* sem_lock_(check_) routines are called in the paths where the rw_mutex
* is not held.
return container_of(ipcp, struct sem_array, sem_perm);
}
+static inline void sem_lock_and_putref(struct sem_array *sma)
+{
+ ipc_lock_by_ptr(&sma->sem_perm);
+ ipc_rcu_putref(sma);
+}
+
+static inline void sem_getref_and_unlock(struct sem_array *sma)
+{
+ ipc_rcu_getref(sma);
+ ipc_unlock(&(sma)->sem_perm);
+}
+
+static inline void sem_putref(struct sem_array *sma)
+{
+ ipc_lock_by_ptr(&sma->sem_perm);
+ ipc_rcu_putref(sma);
+ ipc_unlock(&(sma)->sem_perm);
+}
+
static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
{
ipc_rmid(&sem_ids(ns), &s->sem_perm);
}
ns->used_sems += nsems;
- sma->sem_perm.id = sem_buildid(id, sma->sem_perm.seq);
sma->sem_base = (struct sem *) &sma[1];
/* sma->sem_pending = NULL; */
sma->sem_pending_last = &sma->sem_pending;
- /* sma->undo = NULL; */
+ INIT_LIST_HEAD(&sma->list_id);
sma->sem_nsems = nsems;
sma->sem_ctime = get_seconds();
sem_unlock(sma);
* (They will be freed without any further action in exit_sem()
* or during the next semop.)
*/
- for (un = sma->undo; un; un = un->id_next)
+ assert_spin_locked(&sma->sem_perm.lock);
+ list_for_each_entry(un, &sma->list_id, list_id)
un->semid = -1;
/* Wake up all pending processes and let them fail with EIDRM. */
int i;
if(nsems > SEMMSL_FAST) {
- ipc_rcu_getref(sma);
- sem_unlock(sma);
+ sem_getref_and_unlock(sma);
sem_io = ipc_alloc(sizeof(ushort)*nsems);
if(sem_io == NULL) {
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
- sem_unlock(sma);
+ sem_putref(sma);
return -ENOMEM;
}
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
+ sem_lock_and_putref(sma);
if (sma->sem_perm.deleted) {
sem_unlock(sma);
err = -EIDRM;
int i;
struct sem_undo *un;
- ipc_rcu_getref(sma);
- sem_unlock(sma);
+ sem_getref_and_unlock(sma);
if(nsems > SEMMSL_FAST) {
sem_io = ipc_alloc(sizeof(ushort)*nsems);
if(sem_io == NULL) {
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
- sem_unlock(sma);
+ sem_putref(sma);
return -ENOMEM;
}
}
if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
- sem_unlock(sma);
+ sem_putref(sma);
err = -EFAULT;
goto out_free;
}
for (i = 0; i < nsems; i++) {
if (sem_io[i] > SEMVMX) {
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
- sem_unlock(sma);
+ sem_putref(sma);
err = -ERANGE;
goto out_free;
}
}
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
+ sem_lock_and_putref(sma);
if (sma->sem_perm.deleted) {
sem_unlock(sma);
err = -EIDRM;
for (i = 0; i < nsems; i++)
sma->sem_base[i].semval = sem_io[i];
- for (un = sma->undo; un; un = un->id_next)
+
+ assert_spin_locked(&sma->sem_perm.lock);
+ list_for_each_entry(un, &sma->list_id, list_id) {
for (i = 0; i < nsems; i++)
un->semadj[i] = 0;
+ }
sma->sem_ctime = get_seconds();
/* maybe some queued-up processes were waiting for this */
update_queue(sma);
{
int val = arg.val;
struct sem_undo *un;
+
err = -ERANGE;
if (val > SEMVMX || val < 0)
goto out_unlock;
- for (un = sma->undo; un; un = un->id_next)
+ assert_spin_locked(&sma->sem_perm.lock);
+ list_for_each_entry(un, &sma->list_id, list_id)
un->semadj[semnum] = 0;
+
curr->semval = val;
curr->sempid = task_tgid_vnr(current);
sma->sem_ctime = get_seconds();
return err;
}
-struct sem_setbuf {
- uid_t uid;
- gid_t gid;
- mode_t mode;
-};
-
-static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __user *buf, int version)
+static inline unsigned long
+copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version)
{
switch(version) {
case IPC_64:
- {
- struct semid64_ds tbuf;
-
- if(copy_from_user(&tbuf, buf, sizeof(tbuf)))
+ if (copy_from_user(out, buf, sizeof(*out)))
return -EFAULT;
-
- out->uid = tbuf.sem_perm.uid;
- out->gid = tbuf.sem_perm.gid;
- out->mode = tbuf.sem_perm.mode;
-
return 0;
- }
case IPC_OLD:
{
struct semid_ds tbuf_old;
if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
return -EFAULT;
- out->uid = tbuf_old.sem_perm.uid;
- out->gid = tbuf_old.sem_perm.gid;
- out->mode = tbuf_old.sem_perm.mode;
+ out->sem_perm.uid = tbuf_old.sem_perm.uid;
+ out->sem_perm.gid = tbuf_old.sem_perm.gid;
+ out->sem_perm.mode = tbuf_old.sem_perm.mode;
return 0;
}
}
}
-static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
- int cmd, int version, union semun arg)
+/*
+ * This function handles some semctl commands which require the rw_mutex
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rw_mutex is taken inside this function.
+ */
+static int semctl_down(struct ipc_namespace *ns, int semid,
+ int cmd, int version, union semun arg)
{
struct sem_array *sma;
int err;
- struct sem_setbuf uninitialized_var(setbuf);
+ struct semid64_ds semid64;
struct kern_ipc_perm *ipcp;
if(cmd == IPC_SET) {
- if(copy_semid_from_user (&setbuf, arg.buf, version))
+ if (copy_semid_from_user(&semid64, arg.buf, version))
return -EFAULT;
}
- sma = sem_lock_check_down(ns, semid);
- if (IS_ERR(sma))
- return PTR_ERR(sma);
- ipcp = &sma->sem_perm;
-
- err = audit_ipc_obj(ipcp);
- if (err)
- goto out_unlock;
+ ipcp = ipcctl_pre_down(&sem_ids(ns), semid, cmd, &semid64.sem_perm, 0);
+ if (IS_ERR(ipcp))
+ return PTR_ERR(ipcp);
- if (cmd == IPC_SET) {
- err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
- if (err)
- goto out_unlock;
- }
- if (current->euid != ipcp->cuid &&
- current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) {
- err=-EPERM;
- goto out_unlock;
- }
+ sma = container_of(ipcp, struct sem_array, sem_perm);
err = security_sem_semctl(sma, cmd);
if (err)
switch(cmd){
case IPC_RMID:
freeary(ns, ipcp);
- err = 0;
- break;
+ goto out_up;
case IPC_SET:
- ipcp->uid = setbuf.uid;
- ipcp->gid = setbuf.gid;
- ipcp->mode = (ipcp->mode & ~S_IRWXUGO)
- | (setbuf.mode & S_IRWXUGO);
+ ipc_update_perm(&semid64.sem_perm, ipcp);
sma->sem_ctime = get_seconds();
- sem_unlock(sma);
- err = 0;
break;
default:
- sem_unlock(sma);
err = -EINVAL;
- break;
}
- return err;
out_unlock:
sem_unlock(sma);
+out_up:
+ up_write(&sem_ids(ns).rw_mutex);
return err;
}
return err;
case IPC_RMID:
case IPC_SET:
- down_write(&sem_ids(ns).rw_mutex);
- err = semctl_down(ns,semid,semnum,cmd,version,arg);
- up_write(&sem_ids(ns).rw_mutex);
+ err = semctl_down(ns, semid, cmd, version, arg);
return err;
default:
return -EINVAL;
return -ENOMEM;
spin_lock_init(&undo_list->lock);
atomic_set(&undo_list->refcnt, 1);
+ INIT_LIST_HEAD(&undo_list->list_proc);
+
current->sysvsem.undo_list = undo_list;
}
*undo_listp = undo_list;
static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
{
- struct sem_undo **last, *un;
-
- last = &ulp->proc_list;
- un = *last;
- while(un != NULL) {
- if(un->semid==semid)
- break;
- if(un->semid==-1) {
- *last=un->proc_next;
- kfree(un);
- } else {
- last=&un->proc_next;
+ struct sem_undo *walk, *tmp;
+
+ assert_spin_locked(&ulp->lock);
+ list_for_each_entry_safe(walk, tmp, &ulp->list_proc, list_proc) {
+ if (walk->semid == semid)
+ return walk;
+ if (walk->semid == -1) {
+ list_del(&walk->list_proc);
+ kfree(walk);
}
- un=*last;
}
- return un;
+ return NULL;
}
-static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
+/**
+ * find_alloc_undo - Lookup (and if not present create) undo array
+ * @ns: namespace
+ * @semid: semaphore array id
+ *
+ * The function looks up (and if not present creates) the undo structure.
+ * The size of the undo structure depends on the size of the semaphore
+ * array, thus the alloc path is not that straightforward.
+ */
+static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
{
struct sem_array *sma;
struct sem_undo_list *ulp;
goto out;
/* no undo structure around - allocate one. */
+ /* step 1: figure out the size of the semaphore array */
sma = sem_lock_check(ns, semid);
if (IS_ERR(sma))
return ERR_PTR(PTR_ERR(sma));
nsems = sma->sem_nsems;
- ipc_rcu_getref(sma);
- sem_unlock(sma);
+ sem_getref_and_unlock(sma);
+ /* step 2: allocate new undo structure */
new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
if (!new) {
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
- sem_unlock(sma);
+ sem_putref(sma);
return ERR_PTR(-ENOMEM);
}
- new->semadj = (short *) &new[1];
- new->semid = semid;
+ /* step 3: Acquire the lock on the undo list pointer */
spin_lock(&ulp->lock);
+
+ /* step 4: check for races: someone else allocated the undo struct,
+ * semaphore array was destroyed.
+ */
un = lookup_undo(ulp, semid);
if (un) {
spin_unlock(&ulp->lock);
kfree(new);
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
- sem_unlock(sma);
+ sem_putref(sma);
goto out;
}
- ipc_lock_by_ptr(&sma->sem_perm);
- ipc_rcu_putref(sma);
+ sem_lock_and_putref(sma);
if (sma->sem_perm.deleted) {
sem_unlock(sma);
spin_unlock(&ulp->lock);
un = ERR_PTR(-EIDRM);
goto out;
}
- new->proc_next = ulp->proc_list;
- ulp->proc_list = new;
- new->id_next = sma->undo;
- sma->undo = new;
+ /* step 5: initialize & link new undo structure */
+ new->semadj = (short *) &new[1];
+ new->semid = semid;
+ assert_spin_locked(&ulp->lock);
+ list_add(&new->list_proc, &ulp->list_proc);
+ assert_spin_locked(&sma->sem_perm.lock);
+ list_add(&new->list_id, &sma->list_id);
+
sem_unlock(sma);
- un = new;
spin_unlock(&ulp->lock);
+ un = new;
out:
return un;
}
alter = 1;
}
-retry_undos:
if (undos) {
- un = find_undo(ns, semid);
+ un = find_alloc_undo(ns, semid);
if (IS_ERR(un)) {
error = PTR_ERR(un);
goto out_free;
}
/*
- * semid identifiers are not unique - find_undo may have
+ * semid identifiers are not unique - find_alloc_undo may have
* allocated an undo structure, it was invalidated by an RMID
- * and now a new array with received the same id. Check and retry.
+ * and now a new array with received the same id. Check and fail.
*/
- if (un && un->semid == -1) {
- sem_unlock(sma);
- goto retry_undos;
- }
+ error = -EIDRM;
+ if (un && un->semid == -1)
+ goto out_unlock_free;
+
error = -EFBIG;
if (max >= sma->sem_nsems)
goto out_unlock_free;
*/
void exit_sem(struct task_struct *tsk)
{
- struct sem_undo_list *undo_list;
- struct sem_undo *u, **up;
- struct ipc_namespace *ns;
+ struct sem_undo_list *ulp;
+ struct sem_undo *un, *tmp;
- undo_list = tsk->sysvsem.undo_list;
- if (!undo_list)
+ ulp = tsk->sysvsem.undo_list;
+ if (!ulp)
return;
+ tsk->sysvsem.undo_list = NULL;
- if (!atomic_dec_and_test(&undo_list->refcnt))
+ if (!atomic_dec_and_test(&ulp->refcnt))
return;
- ns = tsk->nsproxy->ipc_ns;
- /* There's no need to hold the semundo list lock, as current
- * is the last task exiting for this undo list.
- */
- for (up = &undo_list->proc_list; (u = *up); *up = u->proc_next, kfree(u)) {
+ spin_lock(&ulp->lock);
+
+ list_for_each_entry_safe(un, tmp, &ulp->list_proc, list_proc) {
struct sem_array *sma;
- int nsems, i;
- struct sem_undo *un, **unp;
- int semid;
-
- semid = u->semid;
-
- if(semid == -1)
- continue;
- sma = sem_lock(ns, semid);
+ int i;
+
+ if (un->semid == -1)
+ goto free;
+
+ sma = sem_lock(tsk->nsproxy->ipc_ns, un->semid);
if (IS_ERR(sma))
- continue;
+ goto free;
- if (u->semid == -1)
- goto next_entry;
+ if (un->semid == -1)
+ goto unlock_free;
- BUG_ON(sem_checkid(sma, u->semid));
+ BUG_ON(sem_checkid(sma, un->semid));
- /* remove u from the sma->undo list */
- for (unp = &sma->undo; (un = *unp); unp = &un->id_next) {
- if (u == un)
- goto found;
- }
- printk ("exit_sem undo list error id=%d\n", u->semid);
- goto next_entry;
-found:
- *unp = un->id_next;
- /* perform adjustments registered in u */
- nsems = sma->sem_nsems;
- for (i = 0; i < nsems; i++) {
+ /* remove un from sma->list_id */
+ assert_spin_locked(&sma->sem_perm.lock);
+ list_del(&un->list_id);
+
+ /* perform adjustments registered in un */
+ for (i = 0; i < sma->sem_nsems; i++) {
struct sem * semaphore = &sma->sem_base[i];
- if (u->semadj[i]) {
- semaphore->semval += u->semadj[i];
+ if (un->semadj[i]) {
+ semaphore->semval += un->semadj[i];
/*
* Range checks of the new semaphore value,
* not defined by sus:
sma->sem_otime = get_seconds();
/* maybe some queued-up processes were waiting for this */
update_queue(sma);
-next_entry:
+unlock_free:
sem_unlock(sma);
+free:
+ assert_spin_locked(&ulp->lock);
+ list_del(&un->list_proc);
+ kfree(un);
}
- kfree(undo_list);
+ spin_unlock(&ulp->lock);
+ kfree(ulp);
}
#ifdef CONFIG_PROC_FS
projects / linux-2.6 / blobdiff