ipc: integrate ipc_checkid() into ipc_lock()

This patch introduces a new ipc_lock_check() routine interface:
   . each time ipc_checkid() is called, this is done after calling ipc_lock().
     ipc_checkid() is now called from inside ipc_lock_check().

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix RCU locking]
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 48 insertions, 42 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index 8cf1cf3d5bec..8241264941a2 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -59,8 +59,6 @@ static struct ipc_ids init_shm_ids;
 
 #define shm_ids(ns)     (*((ns)->ids[IPC_SHM_IDS]))
 
-#define shm_lock(ns, id)                \
-        ((struct shmid_kernel*)ipc_lock(&shm_ids(ns),id))
 #define shm_unlock(shp)                 \
         ipc_unlock(&(shp)->shm_perm)
 #define shm_buildid(ns, id, seq)        \
@@ -139,12 +137,15 @@ void __init shm_init (void)
                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 }
 
-static inline int shm_checkid(struct ipc_namespace *ns,
-                struct shmid_kernel *s, int id)
+static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
-        if (ipc_checkid(&shm_ids(ns), &s->shm_perm, id))
-                return -EIDRM;
-        return 0;
+        return (struct shmid_kernel *) ipc_lock(&shm_ids(ns), id);
+}
+
+static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
+                                                int id)
+{
+        return (struct shmid_kernel *) ipc_lock_check(&shm_ids(ns), id);
 }
 
 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
@@ -167,7 +168,7 @@ static void shm_open(struct vm_area_struct *vma)
         struct shmid_kernel *shp;
 
         shp = shm_lock(sfd->ns, sfd->id);
-        BUG_ON(!shp);
+        BUG_ON(IS_ERR(shp));
         shp->shm_atim = get_seconds();
         shp->shm_lprid = task_tgid_vnr(current);
         shp->shm_nattch++;
@@ -213,7 +214,7 @@ static void shm_close(struct vm_area_struct *vma)
         mutex_lock(&shm_ids(ns).mutex);
         /* remove from the list of attaches of the shm segment */
         shp = shm_lock(ns, sfd->id);
-        BUG_ON(!shp);
+        BUG_ON(IS_ERR(shp));
         shp->shm_lprid = task_tgid_vnr(current);
         shp->shm_dtim = get_seconds();
         shp->shm_nattch--;
@@ -662,17 +663,25 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
         {
                 struct shmid64_ds tbuf;
                 int result;
-                memset(&tbuf, 0, sizeof(tbuf));
-                shp = shm_lock(ns, shmid);
-                if(shp==NULL) {
-                        err = -EINVAL;
+
+                if (!buf) {
+                        err = -EFAULT;
                         goto out;
-                } else if (cmd == SHM_STAT) {
+                }
+
+                if (cmd == SHM_STAT) {
+                        shp = shm_lock(ns, shmid);
+                        if (IS_ERR(shp)) {
+                                err = PTR_ERR(shp);
+                                goto out;
+                        }
                         result = shp->shm_perm.id;
                 } else {
-                        err = shm_checkid(ns, shp,shmid);
-                        if(err)
-                                goto out_unlock;
+                        shp = shm_lock_check(ns, shmid);
+                        if (IS_ERR(shp)) {
+                                err = PTR_ERR(shp);
+                                goto out;
+                        }
                         result = 0;
                 }
                 err=-EACCES;
@@ -681,6 +690,7 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
                 err = security_shm_shmctl(shp, cmd);
                 if (err)
                         goto out_unlock;
+                memset(&tbuf, 0, sizeof(tbuf));
                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
                 tbuf.shm_segsz  = shp->shm_segsz;
                 tbuf.shm_atime  = shp->shm_atim;
@@ -699,14 +709,11 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
         case SHM_LOCK:
         case SHM_UNLOCK:
         {
-                shp = shm_lock(ns, shmid);
-                if(shp==NULL) {
-                        err = -EINVAL;
+                shp = shm_lock_check(ns, shmid);
+                if (IS_ERR(shp)) {
+                        err = PTR_ERR(shp);
                         goto out;
                 }
-                err = shm_checkid(ns, shp,shmid);
-                if(err)
-                        goto out_unlock;
 
                 err = audit_ipc_obj(&(shp->shm_perm));
                 if (err)
@@ -756,13 +763,11 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
                  *      the name away when the usage hits zero.
                  */
                 mutex_lock(&shm_ids(ns).mutex);
-                shp = shm_lock(ns, shmid);
-                err = -EINVAL;
-                if (shp == NULL) 
+                shp = shm_lock_check(ns, shmid);
+                if (IS_ERR(shp)) {
+                        err = PTR_ERR(shp);
                         goto out_up;
-                err = shm_checkid(ns, shp, shmid);
-                if(err)
-                        goto out_unlock_up;
+                }
 
                 err = audit_ipc_obj(&(shp->shm_perm));
                 if (err)
@@ -786,18 +791,21 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
 
         case IPC_SET:
         {
+                if (!buf) {
+                        err = -EFAULT;
+                        goto out;
+                }
+
                 if (copy_shmid_from_user (&setbuf, buf, version)) {
                         err = -EFAULT;
                         goto out;
                 }
                 mutex_lock(&shm_ids(ns).mutex);
-                shp = shm_lock(ns, shmid);
-                err=-EINVAL;
-                if(shp==NULL)
+                shp = shm_lock_check(ns, shmid);
+                if (IS_ERR(shp)) {
+                        err = PTR_ERR(shp);
                         goto out_up;
-                err = shm_checkid(ns, shp,shmid);
-                if(err)
-                        goto out_unlock_up;
+                }
                 err = audit_ipc_obj(&(shp->shm_perm));
                 if (err)
                         goto out_unlock_up;
@@ -903,13 +911,11 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
          * additional creator id...
          */
         ns = current->nsproxy->ipc_ns;
-        shp = shm_lock(ns, shmid);
-        if(shp == NULL)
+        shp = shm_lock_check(ns, shmid);
+        if (IS_ERR(shp)) {
+                err = PTR_ERR(shp);
                 goto out;
-
-        err = shm_checkid(ns, shp,shmid);
-        if (err)
-                goto out_unlock;
+        }
 
         err = -EACCES;
         if (ipcperms(&shp->shm_perm, acc_mode))
@@ -970,7 +976,7 @@ invalid:
 out_nattch:
         mutex_lock(&shm_ids(ns).mutex);
         shp = shm_lock(ns, shmid);
-        BUG_ON(!shp);
+        BUG_ON(IS_ERR(shp));
         shp->shm_nattch--;
         if(shp->shm_nattch == 0 &&
            shp->shm_perm.mode & SHM_DEST)