ipc: fix wrong comments
This patch fixes the wrong / obsolete comments in the ipc code. Also adds a missing lock around ipc_get_maxid() in shm_get_stat(). Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nadia Derbey
Linus Torvalds
parent
2802831313
commit
f4566f0485
14
ipc/msg.c
14
ipc/msg.c
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@ -156,6 +156,13 @@ static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
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ipc_rmid(&msg_ids(ns), &s->q_perm);
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}
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/**
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* newque - Create a new msg queue
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* @ns: namespace
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* @params: ptr to the structure that contains the key and msgflg
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*
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* Called with msg_ids.mutex held
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*/
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static int newque(struct ipc_namespace *ns, struct ipc_params *params)
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{
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struct msg_queue *msq;
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@ -250,8 +257,8 @@ static void expunge_all(struct msg_queue *msq, int res)
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/*
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* freeque() wakes up waiters on the sender and receiver waiting queue,
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* removes the message queue from message queue ID
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* IDR, and cleans up all the messages associated with this queue.
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* removes the message queue from message queue ID IDR, and cleans up all the
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* messages associated with this queue.
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*
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* msg_ids.mutex and the spinlock for this message queue are held
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* before freeque() is called. msg_ids.mutex remains locked on exit.
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@ -278,6 +285,9 @@ static void freeque(struct ipc_namespace *ns, struct msg_queue *msq)
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ipc_rcu_putref(msq);
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}
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/*
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* Called with msg_ids.mutex and ipcp locked.
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*/
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static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
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{
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struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
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14
ipc/sem.c
14
ipc/sem.c
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@ -228,6 +228,14 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
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*/
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#define IN_WAKEUP 1
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/**
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* newary - Create a new semaphore set
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* @ns: namespace
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* @params: ptr to the structure that contains key, semflg and nsems
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*
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* Called with sem_ids.mutex held
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*/
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static int newary(struct ipc_namespace *ns, struct ipc_params *params)
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{
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int id;
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@ -281,6 +289,9 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
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}
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/*
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* Called with sem_ids.mutex and ipcp locked.
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*/
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static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
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{
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struct sem_array *sma;
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@ -289,6 +300,9 @@ static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
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return security_sem_associate(sma, semflg);
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}
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/*
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* Called with sem_ids.mutex and ipcp locked.
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*/
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static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
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struct ipc_params *params)
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{
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39
ipc/shm.c
39
ipc/shm.c
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@ -82,6 +82,10 @@ static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
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ipc_init_ids(ids);
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}
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/*
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* Called with shm_ids.mutex and the shp structure locked.
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* Only shm_ids.mutex remains locked on exit.
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*/
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static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
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{
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if (shp->shm_nattch){
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@ -182,6 +186,7 @@ static void shm_open(struct vm_area_struct *vma)
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/*
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* shm_destroy - free the struct shmid_kernel
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*
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* @ns: namespace
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* @shp: struct to free
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*
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* It has to be called with shp and shm_ids.mutex locked,
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@ -343,6 +348,14 @@ static struct vm_operations_struct shm_vm_ops = {
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#endif
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};
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/**
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* newseg - Create a new shared memory segment
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* @ns: namespace
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* @params: ptr to the structure that contains key, size and shmflg
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*
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* Called with shm_ids.mutex held
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*/
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static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
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{
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key_t key = params->key;
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@ -428,6 +441,9 @@ no_file:
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return error;
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}
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/*
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* Called with shm_ids.mutex and ipcp locked.
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*/
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static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
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{
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struct shmid_kernel *shp;
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@ -436,6 +452,9 @@ static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
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return security_shm_associate(shp, shmflg);
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}
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/*
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* Called with shm_ids.mutex and ipcp locked.
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*/
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static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
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struct ipc_params *params)
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{
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@ -558,6 +577,9 @@ static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminf
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}
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}
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/*
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* Called with shm_ids.mutex held
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*/
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static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
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unsigned long *swp)
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{
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@ -573,18 +595,6 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
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struct shmid_kernel *shp;
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struct inode *inode;
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/*
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* idr_find() is called via shm_get(), so with shm_ids.mutex
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* locked. Since ipc_addid() is also called with
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* shm_ids.mutex down, there is no need to add read barriers
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* here to gurantee the writes in ipc_addid() are seen in
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* order here (for Alpha).
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* However idr_find() itself does not necessary require
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* ipc_ids.mutex down. So if idr_find() is used by other
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* places without ipc_ids.mutex down, then it needs read
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* read memory barriers as ipc_lock() does.
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*/
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shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
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if (shp == NULL)
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continue;
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@ -638,8 +648,11 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
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shminfo.shmmin = SHMMIN;
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if(copy_shminfo_to_user (buf, &shminfo, version))
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return -EFAULT;
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/* reading a integer is always atomic */
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mutex_lock(&shm_ids(ns).mutex);
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err = ipc_get_maxid(&shm_ids(ns));
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mutex_unlock(&shm_ids(ns).mutex);
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if(err<0)
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err = 0;
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goto out;
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78
ipc/util.c
78
ipc/util.c
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@ -194,7 +194,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
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* Requires ipc_ids.mutex locked.
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* Returns the LOCKED pointer to the ipc structure if found or NULL
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* if not.
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* If key is found ipc contains its ipc structure
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* If key is found ipc points to the owning ipc structure
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*/
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static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
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@ -258,10 +258,10 @@ int ipc_get_maxid(struct ipc_ids *ids)
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* @new: new IPC permission set
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* @size: limit for the number of used ids
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*
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* Add an entry 'new' to the IPC idr. The permissions object is
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* Add an entry 'new' to the IPC ids idr. The permissions object is
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* initialised and the first free entry is set up and the id assigned
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* is returned. The list is returned in a locked state on success.
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* On failure the list is not locked and -1 is returned.
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* is returned. The 'new' entry is returned in a locked state on success.
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* On failure the entry is not locked and -1 is returned.
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*
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* Called with ipc_ids.mutex held.
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*/
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@ -270,10 +270,6 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
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{
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int id, err;
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/*
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* rcu_dereference()() is not needed here since
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* ipc_ids.mutex is held
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*/
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if (size > IPCMNI)
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size = IPCMNI;
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@ -303,12 +299,12 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
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/**
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* ipcget_new - create a new ipc object
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* @ns: namespace
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* @ids: identifer set
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* @ids: IPC identifer set
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* @ops: the actual creation routine to call
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* @params: its parameters
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*
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* This routine is called sys_msgget, sys_semget() and sys_shmget() when
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* the key is IPC_PRIVATE
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* This routine is called by sys_msgget, sys_semget() and sys_shmget()
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* when the key is IPC_PRIVATE.
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*/
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int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
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struct ipc_ops *ops, struct ipc_params *params)
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@ -330,9 +326,16 @@ int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
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/**
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* ipc_check_perms - check security and permissions for an IPC
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* @ipcp: ipc permission set
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* @ids: identifer set
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* @ops: the actual security routine to call
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* @params: its parameters
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*
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* This routine is called by sys_msgget(), sys_semget() and sys_shmget()
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* when the key is not IPC_PRIVATE and that key already exists in the
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* ids IDR.
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*
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* On success, the IPC id is returned.
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*
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* It is called with ipc_ids.mutex and ipcp->lock held.
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*/
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static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
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struct ipc_params *params)
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@ -353,12 +356,16 @@ static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
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/**
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* ipcget_public - get an ipc object or create a new one
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* @ns: namespace
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* @ids: identifer set
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* @ids: IPC identifer set
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* @ops: the actual creation routine to call
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* @params: its parameters
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*
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* This routine is called sys_msgget, sys_semget() and sys_shmget() when
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* the key is not IPC_PRIVATE
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* This routine is called by sys_msgget, sys_semget() and sys_shmget()
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* when the key is not IPC_PRIVATE.
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* It adds a new entry if the key is not found and does some permission
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* / security checkings if the key is found.
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*
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* On success, the ipc id is returned.
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*/
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int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
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struct ipc_ops *ops, struct ipc_params *params)
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@ -389,6 +396,10 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
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if (ops->more_checks)
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err = ops->more_checks(ipcp, params);
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if (!err)
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/*
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* ipc_check_perms returns the IPC id on
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* success
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*/
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err = ipc_check_perms(ipcp, ops, params);
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}
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ipc_unlock(ipcp);
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@ -401,12 +412,9 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
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/**
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* ipc_rmid - remove an IPC identifier
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* @ids: identifier set
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* @id: ipc perm structure containing the identifier to remove
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* @ids: IPC identifier set
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* @ipcp: ipc perm structure containing the identifier to remove
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*
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* The identifier must be valid, and in use. The kernel will panic if
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* fed an invalid identifier. The entry is removed and internal
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* variables recomputed.
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* ipc_ids.mutex and the spinlock for this ID are held before this
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* function is called, and remain locked on the exit.
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*/
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@ -558,10 +566,12 @@ static void ipc_do_vfree(struct work_struct *work)
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*/
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static void ipc_schedule_free(struct rcu_head *head)
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{
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struct ipc_rcu_grace *grace =
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container_of(head, struct ipc_rcu_grace, rcu);
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struct ipc_rcu_sched *sched =
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container_of(&(grace->data[0]), struct ipc_rcu_sched, data[0]);
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struct ipc_rcu_grace *grace;
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struct ipc_rcu_sched *sched;
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grace = container_of(head, struct ipc_rcu_grace, rcu);
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sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
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data[0]);
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INIT_WORK(&sched->work, ipc_do_vfree);
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schedule_work(&sched->work);
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@ -650,7 +660,7 @@ void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
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}
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/**
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* ipc64_perm_to_ipc_perm - convert old ipc permissions to new
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* ipc64_perm_to_ipc_perm - convert new ipc permissions to old
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* @in: new style IPC permissions
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* @out: old style IPC permissions
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*
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@ -669,6 +679,18 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
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out->seq = in->seq;
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}
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/**
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* ipc_lock - Lock an ipc structure
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* @ids: IPC identifier set
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* @id: ipc id to look for
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*
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* Look for an id in the ipc ids idr and lock the associated ipc object.
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*
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* ipc_ids.mutex is not necessarily held before this function is called,
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* that's why we enter a RCU read section.
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* The ipc object is locked on exit.
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*/
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struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
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{
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struct kern_ipc_perm *out;
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@ -771,8 +793,8 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
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}
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/*
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* File positions: pos 0 -> header, pos n -> ipc id + 1.
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* SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.
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* File positions: pos 0 -> header, pos n -> ipc id = n - 1.
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* SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
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*/
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static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
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{
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@ -807,7 +829,7 @@ static void sysvipc_proc_stop(struct seq_file *s, void *it)
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struct ipc_proc_iface *iface = iter->iface;
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struct ipc_ids *ids;
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/* If we had a locked segment, release it */
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/* If we had a locked structure, release it */
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if (ipc && ipc != SEQ_START_TOKEN)
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ipc_unlock(ipc);
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18
ipc/util.h
18
ipc/util.h
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@ -54,7 +54,7 @@ struct ipc_params {
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* the calls to sys_msgget(), sys_semget(), sys_shmget()
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* . routine to call to create a new ipc object. Can be one of newque,
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* newary, newseg
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* . routine to call to call to check permissions for a new ipc object.
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* . routine to call to check permissions for a new ipc object.
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* Can be one of security_msg_associate, security_sem_associate,
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* security_shm_associate
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* . routine to call for an extra check if needed
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@ -88,7 +88,8 @@ int ipc_get_maxid(struct ipc_ids *);
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/* must be called with both locks acquired. */
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void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
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int ipcperms (struct kern_ipc_perm *ipcp, short flg);
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/* must be called with ipcp locked */
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int ipcperms(struct kern_ipc_perm *ipcp, short flg);
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/* for rare, potentially huge allocations.
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* both function can sleep
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@ -131,6 +132,9 @@ static inline int ipc_buildid(struct ipc_ids *ids, int id, int seq)
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return SEQ_MULTIPLIER * seq + id;
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}
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/*
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* Must be called with ipcp locked
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*/
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static inline int ipc_checkid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp,
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int uid)
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{
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@ -168,6 +172,16 @@ static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
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return out;
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}
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/**
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* ipcget - Common sys_*get() code
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* @ns : namsepace
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* @ids : IPC identifier set
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* @ops : operations to be called on ipc object creation, permission checks
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* and further checks
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* @params : the parameters needed by the previous operations.
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*
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* Common routine called by sys_msgget(), sys_semget() and sys_shmget().
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*/
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static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
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struct ipc_ops *ops, struct ipc_params *params)
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{
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