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Commit f4566f04 authored by Nadia Derbey's avatar Nadia Derbey Committed by Linus Torvalds
Browse files

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: default avatarNadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 28028313

ipc/msg.c

+12 −2
Original line number Diff line number Diff line
@@ -156,6 +156,13 @@ static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) 
	ipc_rmid(&msg_ids(ns), &s->q_perm);

}



/**

 * newque - Create a new msg queue

 * @ns: namespace

 * @params: ptr to the structure that contains the key and msgflg

 *

 * Called with msg_ids.mutex held

 */

static int newque(struct ipc_namespace *ns, struct ipc_params *params)

{

	struct msg_queue *msq;
@@ -250,8 +257,8 @@ static void expunge_all(struct msg_queue *msq, int res) 


/*

 * freeque() wakes up waiters on the sender and receiver waiting queue,

 * removes the message queue from message queue ID

 * IDR, and cleans up all the messages associated with this queue.

 * removes the message queue from message queue ID IDR, and cleans up all the

 * messages associated with this queue.

 *

 * msg_ids.mutex and the spinlock for this message queue are held

 * before freeque() is called. msg_ids.mutex remains locked on exit.
@@ -278,6 +285,9 @@ static void freeque(struct ipc_namespace *ns, struct msg_queue *msq) 
	ipc_rcu_putref(msq);

}



/*

 * Called with msg_ids.mutex and ipcp locked.

 */

static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)

{

	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);

ipc/sem.c

+14 −0
Original line number Diff line number Diff line
@@ -228,6 +228,14 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) 
 */

#define IN_WAKEUP	1



/**

 * newary - Create a new semaphore set

 * @ns: namespace

 * @params: ptr to the structure that contains key, semflg and nsems

 *

 * Called with sem_ids.mutex held

 */



static int newary(struct ipc_namespace *ns, struct ipc_params *params)

{

	int id;
@@ -281,6 +289,9 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) 
}





/*

 * Called with sem_ids.mutex and ipcp locked.

 */

static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)

{

	struct sem_array *sma;
@@ -289,6 +300,9 @@ static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg) 
	return security_sem_associate(sma, semflg);

}



/*

 * Called with sem_ids.mutex and ipcp locked.

 */

static inline int sem_more_checks(struct kern_ipc_perm *ipcp,

				struct ipc_params *params)

{

ipc/shm.c

+26 −13
Original line number Diff line number Diff line
@@ -82,6 +82,10 @@ static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids) 
	ipc_init_ids(ids);

}



/*

 * Called with shm_ids.mutex and the shp structure locked.

 * Only shm_ids.mutex remains locked on exit.

 */

static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)

{

	if (shp->shm_nattch){
@@ -182,6 +186,7 @@ static void shm_open(struct vm_area_struct *vma) 
/*

 * shm_destroy - free the struct shmid_kernel

 *

 * @ns: namespace

 * @shp: struct to free

 *

 * It has to be called with shp and shm_ids.mutex locked,
@@ -343,6 +348,14 @@ static struct vm_operations_struct shm_vm_ops = { 
#endif

};



/**

 * newseg - Create a new shared memory segment

 * @ns: namespace

 * @params: ptr to the structure that contains key, size and shmflg

 *

 * Called with shm_ids.mutex held

 */



static int newseg(struct ipc_namespace *ns, struct ipc_params *params)

{

	key_t key = params->key;
@@ -428,6 +441,9 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) 
	return error;

}



/*

 * Called with shm_ids.mutex and ipcp locked.

 */

static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)

{

	struct shmid_kernel *shp;
@@ -436,6 +452,9 @@ static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg) 
	return security_shm_associate(shp, shmflg);

}



/*

 * Called with shm_ids.mutex and ipcp locked.

 */

static inline int shm_more_checks(struct kern_ipc_perm *ipcp,

				struct ipc_params *params)

{
@@ -558,6 +577,9 @@ static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminf 
	}

}



/*

 * Called with shm_ids.mutex held

 */

static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,

		unsigned long *swp)

{
@@ -573,18 +595,6 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss, 
		struct shmid_kernel *shp;

		struct inode *inode;



		/*

		 * idr_find() is called via shm_get(), so with shm_ids.mutex

		 * locked. Since ipc_addid() is also called with

		 * shm_ids.mutex down, there is no need to add read barriers

		 * here to gurantee the writes in ipc_addid() are seen in

		 * order here (for Alpha).

		 * However idr_find() itself does not necessary require

		 * ipc_ids.mutex down. So if idr_find() is used by other

		 * places without ipc_ids.mutex down, then it needs read

		 * read memory barriers as ipc_lock() does.

		 */



		shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);

		if (shp == NULL)

			continue;
@@ -638,8 +648,11 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf) 
		shminfo.shmmin = SHMMIN;

		if(copy_shminfo_to_user (buf, &shminfo, version))

			return -EFAULT;

		/* reading a integer is always atomic */



		mutex_lock(&shm_ids(ns).mutex);

		err = ipc_get_maxid(&shm_ids(ns));

		mutex_unlock(&shm_ids(ns).mutex);



		if(err<0)

			err = 0;

		goto out;

ipc/util.c

+50 −28
Original line number Diff line number Diff line
@@ -194,7 +194,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header, 
 *	Requires ipc_ids.mutex locked.

 *	Returns the LOCKED pointer to the ipc structure if found or NULL

 *	if not.

 *	If key is found ipc contains its ipc structure

 *	If key is found ipc points to the owning ipc structure

 */

 

static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
@@ -258,10 +258,10 @@ int ipc_get_maxid(struct ipc_ids *ids) 
 *	@new: new IPC permission set

 *	@size: limit for the number of used ids

 *

 *	Add an entry 'new' to the IPC idr. The permissions object is

 *	Add an entry 'new' to the IPC ids idr. The permissions object is

 *	initialised and the first free entry is set up and the id assigned

 *	is returned. The list is returned in a locked state on success.

 *	On failure the list is not locked and -1 is returned.

 *	is returned. The 'new' entry is returned in a locked state on success.

 *	On failure the entry is not locked and -1 is returned.

 *

 *	Called with ipc_ids.mutex held.

 */
@@ -270,10 +270,6 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) 
{

	int id, err;



	/*

	 * rcu_dereference()() is not needed here since

	 * ipc_ids.mutex is held

	 */

	if (size > IPCMNI)

		size = IPCMNI;
@@ -303,12 +299,12 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) 
/**

 *	ipcget_new	-	create a new ipc object

 *	@ns: namespace

 *	@ids: identifer set

 *	@ids: IPC identifer set

 *	@ops: the actual creation routine to call

 *	@params: its parameters

 *

 *	This routine is called sys_msgget, sys_semget() and sys_shmget() when

 *	the key is IPC_PRIVATE

 *	This routine is called by sys_msgget, sys_semget() and sys_shmget()

 *	when the key is IPC_PRIVATE.

 */

int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,

		struct ipc_ops *ops, struct ipc_params *params)
@@ -330,9 +326,16 @@ int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, 
/**

 *	ipc_check_perms	-	check security and permissions for an IPC

 *	@ipcp: ipc permission set

 *	@ids: identifer set

 *	@ops: the actual security routine to call

 *	@params: its parameters

 *

 *	This routine is called by sys_msgget(), sys_semget() and sys_shmget()

 *      when the key is not IPC_PRIVATE and that key already exists in the

 *      ids IDR.

 *

 *	On success, the IPC id is returned.

 *

 *	It is called with ipc_ids.mutex and ipcp->lock held.

 */

static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,

			struct ipc_params *params)
@@ -353,12 +356,16 @@ static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops, 
/**

 *	ipcget_public	-	get an ipc object or create a new one

 *	@ns: namespace

 *	@ids: identifer set

 *	@ids: IPC identifer set

 *	@ops: the actual creation routine to call

 *	@params: its parameters

 *

 *	This routine is called sys_msgget, sys_semget() and sys_shmget() when

 *	the key is not IPC_PRIVATE

 *	This routine is called by sys_msgget, sys_semget() and sys_shmget()

 *	when the key is not IPC_PRIVATE.

 *	It adds a new entry if the key is not found and does some permission

 *      / security checkings if the key is found.

 *

 *	On success, the ipc id is returned.

 */

int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,

		struct ipc_ops *ops, struct ipc_params *params)
@@ -389,6 +396,10 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, 
			if (ops->more_checks)

				err = ops->more_checks(ipcp, params);

			if (!err)

				/*

				 * ipc_check_perms returns the IPC id on

				 * success

				 */

				err = ipc_check_perms(ipcp, ops, params);

		}

		ipc_unlock(ipcp);
@@ -401,12 +412,9 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, 


/**

 *	ipc_rmid	-	remove an IPC identifier

 *	@ids: identifier set

 *	@id: ipc perm structure containing the identifier to remove

 *	@ids: IPC identifier set

 *	@ipcp: ipc perm structure containing the identifier to remove

 *

 *	The identifier must be valid, and in use. The kernel will panic if

 *	fed an invalid identifier. The entry is removed and internal

 *	variables recomputed.

 *	ipc_ids.mutex and the spinlock for this ID are held before this

 *	function is called, and remain locked on the exit.

 */
@@ -558,10 +566,12 @@ static void ipc_do_vfree(struct work_struct *work) 
 */

static void ipc_schedule_free(struct rcu_head *head)

{

	struct ipc_rcu_grace *grace =

		container_of(head, struct ipc_rcu_grace, rcu);

	struct ipc_rcu_sched *sched =

			container_of(&(grace->data[0]), struct ipc_rcu_sched, data[0]);

	struct ipc_rcu_grace *grace;

	struct ipc_rcu_sched *sched;



	grace = container_of(head, struct ipc_rcu_grace, rcu);

	sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,

				data[0]);



	INIT_WORK(&sched->work, ipc_do_vfree);

	schedule_work(&sched->work);
@@ -650,7 +660,7 @@ void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out) 
}



/**

 *	ipc64_perm_to_ipc_perm	-	convert old ipc permissions to new

 *	ipc64_perm_to_ipc_perm	-	convert new ipc permissions to old

 *	@in: new style IPC permissions

 *	@out: old style IPC permissions

 *
@@ -669,6 +679,18 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out) 
	out->seq	= in->seq;

}



/**

 * ipc_lock - Lock an ipc structure

 * @ids: IPC identifier set

 * @id: ipc id to look for

 *

 * Look for an id in the ipc ids idr and lock the associated ipc object.

 *

 * ipc_ids.mutex is not necessarily held before this function is called,

 * that's why we enter a RCU read section.

 * The ipc object is locked on exit.

 */



struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)

{

	struct kern_ipc_perm *out;
@@ -771,8 +793,8 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) 
}



/*

 * File positions: pos 0 -> header, pos n -> ipc id + 1.

 * SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.

 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.

 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.

 */

static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)

{
@@ -807,7 +829,7 @@ static void sysvipc_proc_stop(struct seq_file *s, void *it) 
	struct ipc_proc_iface *iface = iter->iface;

	struct ipc_ids *ids;



	/* If we had a locked segment, release it */

	/* If we had a locked structure, release it */

	if (ipc && ipc != SEQ_START_TOKEN)

		ipc_unlock(ipc);

ipc/util.h

+16 −2
Original line number Diff line number Diff line
@@ -54,7 +54,7 @@ struct ipc_params { 
 * the calls to sys_msgget(), sys_semget(), sys_shmget()

 *      . routine to call to create a new ipc object. Can be one of newque,

 *        newary, newseg

 *      . routine to call to call to check permissions for a new ipc object.

 *      . routine to call to check permissions for a new ipc object.

 *        Can be one of security_msg_associate, security_sem_associate,

 *        security_shm_associate

 *      . routine to call for an extra check if needed
@@ -88,6 +88,7 @@ int ipc_get_maxid(struct ipc_ids *); 
/* must be called with both locks acquired. */

void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);



/* must be called with ipcp locked */

int ipcperms(struct kern_ipc_perm *ipcp, short flg);



/* for rare, potentially huge allocations.
@@ -131,6 +132,9 @@ static inline int ipc_buildid(struct ipc_ids *ids, int id, int seq) 
	return SEQ_MULTIPLIER * seq + id;

}



/*

 * Must be called with ipcp locked

 */

static inline int ipc_checkid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp,

				int uid)

{
@@ -168,6 +172,16 @@ static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, 
	return out;

}



/**

 * ipcget - Common sys_*get() code

 * @ns : namsepace

 * @ids : IPC identifier set

 * @ops : operations to be called on ipc object creation, permission checks

 *        and further checks

 * @params : the parameters needed by the previous operations.

 *

 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().

 */

static inline int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,

			struct ipc_ops *ops, struct ipc_params *params)

{