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SubjectRegister semundo task watcher
Make the semaphore undo code use a task watcher instead of hooking into
copy_process() and do_exit() directly.

Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
---
include/linux/sem.h | 17 -----------------
ipc/sem.c | 12 ++++++++----
kernel/exit.c | 2 --
kernel/fork.c | 6 +-----
4 files changed, 9 insertions(+), 28 deletions(-)

Index: linux-2.6.19/ipc/sem.c
===================================================================
--- linux-2.6.19.orig/ipc/sem.c
+++ linux-2.6.19/ipc/sem.c
@@ -81,10 +81,11 @@
#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/seq_file.h>
#include <linux/mutex.h>
#include <linux/nsproxy.h>
+#include <linux/init.h>

#include <asm/uaccess.h>
#include "util.h"

#define sem_ids(ns) (*((ns)->ids[IPC_SEM_IDS]))
@@ -1287,11 +1288,11 @@ asmlinkage long sys_semop (int semid, st
* See the notes above unlock_semundo() regarding the spin_lock_init()
* in this code. Initialize the undo_list->lock here instead of get_undo_list()
* because of the reasoning in the comment above unlock_semundo.
*/

-int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
+static int __task_init copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
{
struct sem_undo_list *undo_list;
int error;

if (clone_flags & CLONE_SYSVSEM) {
@@ -1303,10 +1304,11 @@ int copy_semundo(unsigned long clone_fla
} else
tsk->sysvsem.undo_list = NULL;

return 0;
}
+DEFINE_TASK_INITCALL(copy_semundo);

/*
* add semadj values to semaphores, free undo structures.
* undo structures are not freed when semaphore arrays are destroyed
* so some of them may be out of date.
@@ -1316,22 +1318,22 @@ int copy_semundo(unsigned long clone_fla
* should we queue up and wait until we can do so legally?
* The original implementation attempted to do this (queue and wait).
* The current implementation does not do so. The POSIX standard
* and SVID should be consulted to determine what behavior is mandated.
*/
-void exit_sem(struct task_struct *tsk)
+static int __task_free exit_sem(unsigned long ignored, struct task_struct *tsk)
{
struct sem_undo_list *undo_list;
struct sem_undo *u, **up;
struct ipc_namespace *ns;

undo_list = tsk->sysvsem.undo_list;
if (!undo_list)
- return;
+ return 0;

if (!atomic_dec_and_test(&undo_list->refcnt))
- return;
+ return 0;

ns = tsk->nsproxy->ipc_ns;
/* There's no need to hold the semundo list lock, as current
* is the last task exiting for this undo list.
*/
@@ -1394,11 +1396,13 @@ found:
update_queue(sma);
next_entry:
sem_unlock(sma);
}
kfree(undo_list);
+ return 0;
}
+DEFINE_TASK_FREECALL(exit_sem);

#ifdef CONFIG_PROC_FS
static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
{
struct sem_array *sma = it;
Index: linux-2.6.19/kernel/exit.c
===================================================================
--- linux-2.6.19.orig/kernel/exit.c
+++ linux-2.6.19/kernel/exit.c
@@ -45,11 +45,10 @@
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>

-extern void sem_exit (void);
extern struct task_struct *child_reaper;

static void exit_mm(struct task_struct * tsk);

static void __unhash_process(struct task_struct *p)
@@ -916,11 +915,10 @@ fastcall NORET_TYPE void do_exit(long co
exit_mm(tsk);
notify_task_watchers(WATCH_TASK_FREE, code, tsk);

if (group_dead)
acct_process();
- exit_sem(tsk);
__exit_files(tsk);
__exit_fs(tsk);
exit_thread();
cpuset_exit(tsk);
exit_keys(tsk);
Index: linux-2.6.19/kernel/fork.c
===================================================================
--- linux-2.6.19.orig/kernel/fork.c
+++ linux-2.6.19/kernel/fork.c
@@ -1102,14 +1102,12 @@ static struct task_struct *copy_process(
#endif

if ((retval = security_task_alloc(p)))
goto bad_fork_cleanup_policy;
/* copy all the process information */
- if ((retval = copy_semundo(clone_flags, p)))
- goto bad_fork_cleanup_security;
if ((retval = copy_files(clone_flags, p)))
- goto bad_fork_cleanup_semundo;
+ goto bad_fork_cleanup_security;
if ((retval = copy_fs(clone_flags, p)))
goto bad_fork_cleanup_files;
if ((retval = copy_sighand(clone_flags, p)))
goto bad_fork_cleanup_fs;
if ((retval = copy_signal(clone_flags, p)))
@@ -1276,12 +1274,10 @@ bad_fork_cleanup_sighand:
__cleanup_sighand(p->sighand);
bad_fork_cleanup_fs:
exit_fs(p); /* blocking */
bad_fork_cleanup_files:
exit_files(p); /* blocking */
-bad_fork_cleanup_semundo:
- exit_sem(p);
bad_fork_cleanup_security:
security_task_free(p);
bad_fork_cleanup_policy:
#ifdef CONFIG_NUMA
mpol_free(p->mempolicy);
Index: linux-2.6.19/include/linux/sem.h
===================================================================
--- linux-2.6.19.orig/include/linux/sem.h
+++ linux-2.6.19/include/linux/sem.h
@@ -136,25 +136,8 @@ struct sem_undo_list {

struct sysv_sem {
struct sem_undo_list *undo_list;
};

-#ifdef CONFIG_SYSVIPC
-
-extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk);
-extern void exit_sem(struct task_struct *tsk);
-
-#else
-static inline int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
-{
- return 0;
-}
-
-static inline void exit_sem(struct task_struct *tsk)
-{
- return;
-}
-#endif
-
#endif /* __KERNEL__ */

#endif /* _LINUX_SEM_H */
--
-
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