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IPC/semaphores: code factorisation
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Trivial patch which adds some small locking functions and makes use of them to
factorize some part of the code and to make it cleaner.

Signed-off-by: Pierre Peiffer <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Cc: Nadia Derbey <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@torvalds
Pierre Peiffer authored and torvalds committed Apr 29, 2008
1 parent 6546bc4 commit 6ff3797
Showing 1 changed file with 31 additions and 30 deletions.
61 changes: 31 additions & 30 deletions ipc/sem.c
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,25 @@ static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns,
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);
Expand Down Expand Up @@ -698,19 +717,15 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
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;
Expand All @@ -731,38 +746,30 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
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;
Expand Down Expand Up @@ -1042,14 +1049,11 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
return ERR_PTR(PTR_ERR(sma));

nsems = sma->sem_nsems;
ipc_rcu_getref(sma);
sem_unlock(sma);
sem_getref_and_unlock(sma);

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];
Expand All @@ -1060,13 +1064,10 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int 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);
Expand Down

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