Commit 4daa28f6 authored by Manfred Spraul's avatar Manfred Spraul Committed by Linus Torvalds
Browse files

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: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 00c2bf85

include/linux/sem.h

+6 −6
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ struct sem_array { 
	struct sem		*sem_base;	/* ptr to first semaphore in array */

	struct sem_queue	*sem_pending;	/* pending operations to be processed */

	struct sem_queue	**sem_pending_last; /* last pending operation */

	struct sem_undo		*undo;		/* undo requests on this array */

	struct list_head	list_id;	/* undo requests on this array */

	unsigned long		sem_nsems;	/* no. of semaphores in array */

};
@@ -118,8 +118,8 @@ struct sem_queue { 
 * when the process exits.

 */

struct sem_undo {

	struct sem_undo *	proc_next;	/* next entry on this process */

	struct sem_undo *	id_next;	/* next entry on this semaphore set */

	struct list_head	list_proc;	/* per-process list: all undos from one process */

	struct list_head	list_id;	/* per semaphore array list: all undos for one array */

	int			semid;		/* semaphore set identifier */

	short *			semadj;		/* array of adjustments, one per semaphore */

};
@@ -130,7 +130,7 @@ struct sem_undo { 
struct sem_undo_list {

	atomic_t		refcnt;

	spinlock_t		lock;

	struct sem_undo	*proc_list;

	struct list_head	list_proc;

};



struct sysv_sem {

ipc/sem.c

+89 −74
Original line number Diff line number Diff line
@@ -274,7 +274,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) 
	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);
@@ -536,7 +536,8 @@ static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) 
	 * (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. */
@@ -763,9 +764,12 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, 


		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);
@@ -797,12 +801,15 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, 
	{

		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();
@@ -952,6 +959,8 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp) 
			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;
@@ -960,25 +969,30 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp) 


static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)

{

	struct sem_undo **last, *un;

	struct sem_undo *walk, *tmp;



	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;

	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;
@@ -997,6 +1011,7 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid) 
		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));
@@ -1004,15 +1019,19 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid) 
	nsems = sma->sem_nsems;

	sem_getref_and_unlock(sma);



	/* step 2: allocate new undo structure */

	new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);

	if (!new) {

		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);
@@ -1028,13 +1047,17 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid) 
		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;

}
@@ -1090,9 +1113,8 @@ asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops, 
			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;
@@ -1107,14 +1129,14 @@ retry_undos: 
	}



	/*

	 * 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;
@@ -1243,56 +1265,44 @@ int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) 
 */

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;

		int i;



		semid = u->semid;

		if (un->semid == -1)

			goto free;



		if(semid == -1)

			continue;

		sma = sem_lock(ns, semid);

		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:
@@ -1316,10 +1326,15 @@ found: 
		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

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