diff options
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 66 |
1 files changed, 47 insertions, 19 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index b204feb38274..4cd402e4cfeb 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -96,14 +96,14 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp); static int sysvipc_shm_proc_show(struct seq_file *s, void *it); #endif -int shm_init_ns(struct ipc_namespace *ns) +void shm_init_ns(struct ipc_namespace *ns) { ns->shm_ctlmax = SHMMAX; ns->shm_ctlall = SHMALL; ns->shm_ctlmni = SHMMNI; ns->shm_rmid_forced = 0; ns->shm_tot = 0; - return ipc_init_ids(&shm_ids(ns)); + ipc_init_ids(&shm_ids(ns)); } /* @@ -136,9 +136,8 @@ void shm_exit_ns(struct ipc_namespace *ns) static int __init ipc_ns_init(void) { - const int err = shm_init_ns(&init_ipc_ns); - WARN(err, "ipc: sysv shm_init_ns failed: %d\n", err); - return err; + shm_init_ns(&init_ipc_ns); + return 0; } pure_initcall(ipc_ns_init); @@ -180,16 +179,34 @@ static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace */ static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id) { - struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); + struct kern_ipc_perm *ipcp; + + rcu_read_lock(); + ipcp = ipc_obtain_object_idr(&shm_ids(ns), id); + if (IS_ERR(ipcp)) + goto err; + ipc_lock_object(ipcp); + /* + * ipc_rmid() may have already freed the ID while ipc_lock_object() + * was spinning: here verify that the structure is still valid. + * Upon races with RMID, return -EIDRM, thus indicating that + * the ID points to a removed identifier. + */ + if (ipc_valid_object(ipcp)) { + /* return a locked ipc object upon success */ + return container_of(ipcp, struct shmid_kernel, shm_perm); + } + + ipc_unlock_object(ipcp); + ipcp = ERR_PTR(-EIDRM); +err: + rcu_read_unlock(); /* * Callers of shm_lock() must validate the status of the returned ipc - * object pointer (as returned by ipc_lock()), and error out as - * appropriate. + * object pointer and error out as appropriate. */ - if (IS_ERR(ipcp)) - return (void *)ipcp; - return container_of(ipcp, struct shmid_kernel, shm_perm); + return (void *)ipcp; } static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp) @@ -684,6 +701,8 @@ no_id: if (is_file_hugepages(file) && shp->mlock_user) user_shm_unlock(size, shp->mlock_user); fput(file); + ipc_rcu_putref(&shp->shm_perm, shm_rcu_free); + return error; no_file: call_rcu(&shp->shm_perm.rcu, shm_rcu_free); return error; @@ -879,7 +898,7 @@ static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd, down_write(&shm_ids(ns).rwsem); rcu_read_lock(); - ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd, + ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd, &shmid64->shm_perm, 0); if (IS_ERR(ipcp)) { err = PTR_ERR(ipcp); @@ -930,7 +949,7 @@ static int shmctl_ipc_info(struct ipc_namespace *ns, shminfo->shmall = ns->shm_ctlall; shminfo->shmmin = SHMMIN; down_read(&shm_ids(ns).rwsem); - err = ipc_get_maxid(&shm_ids(ns)); + err = ipc_get_maxidx(&shm_ids(ns)); up_read(&shm_ids(ns).rwsem); if (err < 0) err = 0; @@ -950,7 +969,7 @@ static int shmctl_shm_info(struct ipc_namespace *ns, shm_info->shm_tot = ns->shm_tot; shm_info->swap_attempts = 0; shm_info->swap_successes = 0; - err = ipc_get_maxid(&shm_ids(ns)); + err = ipc_get_maxidx(&shm_ids(ns)); up_read(&shm_ids(ns).rwsem); if (err < 0) err = 0; @@ -962,7 +981,6 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, int cmd, struct shmid64_ds *tbuf) { struct shmid_kernel *shp; - int id = 0; int err; memset(tbuf, 0, sizeof(*tbuf)); @@ -974,7 +992,6 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, err = PTR_ERR(shp); goto out_unlock; } - id = shp->shm_perm.id; } else { /* IPC_STAT */ shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { @@ -1024,10 +1041,21 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, tbuf->shm_lpid = pid_vnr(shp->shm_lprid); tbuf->shm_nattch = shp->shm_nattch; - ipc_unlock_object(&shp->shm_perm); - rcu_read_unlock(); - return id; + if (cmd == IPC_STAT) { + /* + * As defined in SUS: + * Return 0 on success + */ + err = 0; + } else { + /* + * SHM_STAT and SHM_STAT_ANY (both Linux specific) + * Return the full id, including the sequence number + */ + err = shp->shm_perm.id; + } + ipc_unlock_object(&shp->shm_perm); out_unlock: rcu_read_unlock(); return err; |