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authorChristophe JAILLET <christophe.jaillet@wanadoo.fr>2023-07-09 19:12:55 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-08-18 20:18:51 +0300
commitb46fae06153da31a80ab0f3e98819416fc134725 (patch)
tree3c991aa36c8b628558ebc39cb64f53b4aadd2c8b /ipc
parent4264be505d9f3657de9626f551099e595b2ae7fe (diff)
downloadlinux-b46fae06153da31a80ab0f3e98819416fc134725.tar.xz
ipc/sem: use flexible array in 'struct sem_undo'
Turn 'semadj' in 'struct sem_undo' into a flexible array. The advantages are: - save the size of a pointer when the new undo structure is allocated - avoid some always ugly pointer arithmetic to get the address of semadj - avoid an indirection when the array is accessed While at it, use struct_size() to compute the size of the new undo structure. Link: https://lkml.kernel.org/r/1ba993d443ad7e16ac2b1902adab1f05ebdfa454.1688918791.git.christophe.jaillet@wanadoo.fr Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Manfred Spraul <manfred@colorfullife.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/sem.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index 00f88aa01ac5..a39cdc7bf88f 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -152,7 +152,7 @@ struct sem_undo {
struct list_head list_id; /* per semaphore array list:
* all undos for one array */
int semid; /* semaphore set identifier */
- short *semadj; /* array of adjustments */
+ short semadj[]; /* array of adjustments */
/* one per semaphore */
};
@@ -1938,8 +1938,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
rcu_read_unlock();
/* step 2: allocate new undo structure */
- new = kvzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems,
- GFP_KERNEL_ACCOUNT);
+ new = kvzalloc(struct_size(new, semadj, nsems), GFP_KERNEL_ACCOUNT);
if (!new) {
ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
return ERR_PTR(-ENOMEM);
@@ -1967,7 +1966,6 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
goto success;
}
/* step 5: initialize & link new undo structure */
- new->semadj = (short *) &new[1];
new->ulp = ulp;
new->semid = semid;
assert_spin_locked(&ulp->lock);