ipc: fix wrong comments
This patch fixes the wrong / obsolete comments in the ipc code. Also adds
a missing lock around ipc_get_maxid() in shm_get_stat().
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>
diff --git a/ipc/shm.c b/ipc/shm.c
index e2de16e..f28f2a3 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -82,6 +82,10 @@
ipc_init_ids(ids);
}
+/*
+ * Called with shm_ids.mutex and the shp structure locked.
+ * Only shm_ids.mutex remains locked on exit.
+ */
static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
{
if (shp->shm_nattch){
@@ -182,6 +186,7 @@
/*
* shm_destroy - free the struct shmid_kernel
*
+ * @ns: namespace
* @shp: struct to free
*
* It has to be called with shp and shm_ids.mutex locked,
@@ -343,6 +348,14 @@
#endif
};
+/**
+ * newseg - Create a new shared memory segment
+ * @ns: namespace
+ * @params: ptr to the structure that contains key, size and shmflg
+ *
+ * Called with shm_ids.mutex held
+ */
+
static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
{
key_t key = params->key;
@@ -428,6 +441,9 @@
return error;
}
+/*
+ * Called with shm_ids.mutex and ipcp locked.
+ */
static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
{
struct shmid_kernel *shp;
@@ -436,6 +452,9 @@
return security_shm_associate(shp, shmflg);
}
+/*
+ * Called with shm_ids.mutex and ipcp locked.
+ */
static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
struct ipc_params *params)
{
@@ -558,6 +577,9 @@
}
}
+/*
+ * Called with shm_ids.mutex held
+ */
static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
unsigned long *swp)
{
@@ -573,18 +595,6 @@
struct shmid_kernel *shp;
struct inode *inode;
- /*
- * idr_find() is called via shm_get(), so with shm_ids.mutex
- * locked. Since ipc_addid() is also called with
- * shm_ids.mutex down, there is no need to add read barriers
- * here to gurantee the writes in ipc_addid() are seen in
- * order here (for Alpha).
- * However idr_find() itself does not necessary require
- * ipc_ids.mutex down. So if idr_find() is used by other
- * places without ipc_ids.mutex down, then it needs read
- * read memory barriers as ipc_lock() does.
- */
-
shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
if (shp == NULL)
continue;
@@ -638,8 +648,11 @@
shminfo.shmmin = SHMMIN;
if(copy_shminfo_to_user (buf, &shminfo, version))
return -EFAULT;
- /* reading a integer is always atomic */
+
+ mutex_lock(&shm_ids(ns).mutex);
err = ipc_get_maxid(&shm_ids(ns));
+ mutex_unlock(&shm_ids(ns).mutex);
+
if(err<0)
err = 0;
goto out;