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-rw-r--r--ipc/sem.c44
1 files changed, 30 insertions, 14 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index 45c7e573c20..019e21332dd 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -80,7 +80,7 @@
#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/seq_file.h>
-#include <linux/mutex.h>
+#include <linux/rwsem.h>
#include <linux/nsproxy.h>
#include <asm/uaccess.h>
@@ -148,7 +148,7 @@ void sem_exit_ns(struct ipc_namespace *ns)
int next_id;
int total, in_use;
- mutex_lock(&sem_ids(ns).mutex);
+ down_write(&sem_ids(ns).rw_mutex);
in_use = sem_ids(ns).in_use;
@@ -160,7 +160,7 @@ void sem_exit_ns(struct ipc_namespace *ns)
freeary(ns, sma);
total++;
}
- mutex_unlock(&sem_ids(ns).mutex);
+ up_write(&sem_ids(ns).rw_mutex);
kfree(ns->ids[IPC_SEM_IDS]);
ns->ids[IPC_SEM_IDS] = NULL;
@@ -174,6 +174,22 @@ void __init sem_init (void)
IPC_SEM_IDS, sysvipc_sem_proc_show);
}
+/*
+ * This routine is called in the paths where the rw_mutex is held to protect
+ * access to the idr tree.
+ */
+static inline struct sem_array *sem_lock_check_down(struct ipc_namespace *ns,
+ int id)
+{
+ struct kern_ipc_perm *ipcp = ipc_lock_check_down(&sem_ids(ns), id);
+
+ return container_of(ipcp, struct sem_array, sem_perm);
+}
+
+/*
+ * sem_lock_(check_) routines are called in the paths where the rw_mutex
+ * is not held.
+ */
static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
{
struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);
@@ -233,7 +249,7 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
* @ns: namespace
* @params: ptr to the structure that contains key, semflg and nsems
*
- * Called with sem_ids.mutex held
+ * Called with sem_ids.rw_mutex held (as a writer)
*/
static int newary(struct ipc_namespace *ns, struct ipc_params *params)
@@ -290,7 +306,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
/*
- * Called with sem_ids.mutex and ipcp locked.
+ * Called with sem_ids.rw_mutex and ipcp locked.
*/
static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
{
@@ -301,7 +317,7 @@ static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
}
/*
- * Called with sem_ids.mutex and ipcp locked.
+ * Called with sem_ids.rw_mutex and ipcp locked.
*/
static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
struct ipc_params *params)
@@ -528,9 +544,9 @@ static int count_semzcnt (struct sem_array * sma, ushort semnum)
return semzcnt;
}
-/* Free a semaphore set. freeary() is called with sem_ids.mutex locked and
- * the spinlock for this semaphore set hold. sem_ids.mutex remains locked
- * on exit.
+/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
+ * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
+ * remains locked on exit.
*/
static void freeary(struct ipc_namespace *ns, struct sem_array *sma)
{
@@ -615,7 +631,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
seminfo.semmnu = SEMMNU;
seminfo.semmap = SEMMAP;
seminfo.semume = SEMUME;
- mutex_lock(&sem_ids(ns).mutex);
+ down_read(&sem_ids(ns).rw_mutex);
if (cmd == SEM_INFO) {
seminfo.semusz = sem_ids(ns).in_use;
seminfo.semaem = ns->used_sems;
@@ -624,7 +640,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
seminfo.semaem = SEMAEM;
}
max_id = ipc_get_maxid(&sem_ids(ns));
- mutex_unlock(&sem_ids(ns).mutex);
+ up_read(&sem_ids(ns).rw_mutex);
if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo)))
return -EFAULT;
return (max_id < 0) ? 0: max_id;
@@ -895,7 +911,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
if(copy_semid_from_user (&setbuf, arg.buf, version))
return -EFAULT;
}
- sma = sem_lock_check(ns, semid);
+ sma = sem_lock_check_down(ns, semid);
if (IS_ERR(sma))
return PTR_ERR(sma);
@@ -976,9 +992,9 @@ asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
return err;
case IPC_RMID:
case IPC_SET:
- mutex_lock(&sem_ids(ns).mutex);
+ down_write(&sem_ids(ns).rw_mutex);
err = semctl_down(ns,semid,semnum,cmd,version,arg);
- mutex_unlock(&sem_ids(ns).mutex);
+ up_write(&sem_ids(ns).rw_mutex);
return err;
default:
return -EINVAL;