linux-kernel - [PATCH 04/20] ipc: Drop non-RCU allocation

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Date:   Thu, 25 May 2017 20:50:51 +0200
From:   Manfred Spraul <manfred@...orfullife.com>
To:     mtk.manpages@...il.com, Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, 1vier1@....de,
        Davidlohr Bueso <dave@...olabs.net>, mingo@...nel.org,
        peterz@...radead.org, fabf@...net.be,
        Manfred Spraul <manfred@...orfullife.com>
Subject: [PATCH 04/20] ipc: Drop non-RCU allocation

The only users of ipc_alloc() were ipc_rcu_alloc() and the on-heap
sem_io fall-back memory. Better to just open-code these to make things
easier to read.

Signed-off-by: Kees Cook <keescook@...omium.org>

[manfred@...orfullife.com: Rediff due to inclusion of memset() into
ipc_rcu_alloc().]

Signed-off-by: Manfred Spraul <manfred@...orfullife.com>
---
 ipc/sem.c  |  8 +++++---
 ipc/util.c | 27 +++------------------------
 ipc/util.h |  6 ------
 3 files changed, 8 insertions(+), 33 deletions(-)

diff --git a/ipc/sem.c b/ipc/sem.c
index bdff6d9..484ccf8 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1368,7 +1368,8 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 			}
 			sem_unlock(sma, -1);
 			rcu_read_unlock();
-			sem_io = ipc_alloc(sizeof(ushort)*nsems);
+			sem_io = kvmalloc_array(nsems, sizeof(ushort),
+						GFP_KERNEL);
 			if (sem_io == NULL) {
 				ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
 				return -ENOMEM;
@@ -1402,7 +1403,8 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 		rcu_read_unlock();
 
 		if (nsems > SEMMSL_FAST) {
-			sem_io = ipc_alloc(sizeof(ushort)*nsems);
+			sem_io = kvmalloc_array(nsems, sizeof(ushort),
+						GFP_KERNEL);
 			if (sem_io == NULL) {
 				ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
 				return -ENOMEM;
@@ -1480,7 +1482,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
 	wake_up_q(&wake_q);
 out_free:
 	if (sem_io != fast_sem_io)
-		ipc_free(sem_io);
+		kvfree(sem_io);
 	return err;
 }
 
diff --git a/ipc/util.c b/ipc/util.c
index 9dcc08b..dd73feb 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -395,29 +395,6 @@ void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 }
 
 /**
- * ipc_alloc -	allocate ipc space
- * @size: size desired
- *
- * Allocate memory from the appropriate pools and return a pointer to it.
- * NULL is returned if the allocation fails
- */
-void *ipc_alloc(int size)
-{
-	return kvmalloc(size, GFP_KERNEL);
-}
-
-/**
- * ipc_free - free ipc space
- * @ptr: pointer returned by ipc_alloc
- *
- * Free a block created with ipc_alloc().
- */
-void ipc_free(void *ptr)
-{
-	kvfree(ptr);
-}
-
-/**
  * ipc_rcu_alloc - allocate ipc space
  * @size: size desired
  *
@@ -429,9 +406,11 @@ struct kern_ipc_perm *ipc_rcu_alloc(int size)
 	/*
 	 * We prepend the allocation with the rcu struct
 	 */
-	struct kern_ipc_perm *out = ipc_alloc(size);
+	struct kern_ipc_perm *out = kvmalloc(size, GFP_KERNEL);
 	if (unlikely(!out))
 		return NULL;
+
+	memset(out, 0, size);
 	atomic_set(&out->refcount, 1);
 	return out;
 }
diff --git a/ipc/util.h b/ipc/util.h
index 09d0f91..2578fd9 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -107,12 +107,6 @@ void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 /* must be called with ipcp locked */
 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 
-/* for rare, potentially huge allocations.
- * both function can sleep
- */
-void *ipc_alloc(int size);
-void ipc_free(void *ptr);
-
 /*
  * For allocation that need to be freed by RCU.
  * Objects are reference counted, they start with reference count 1.
-- 
2.9.3