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Date: Fri, 13 Apr 2007 21:13:13 -0600
From: ebiederm@...ssion.com (Eric W. Biederman)
To: Oleg Nesterov <oleg@...sign.ru>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Davide Libenzi <davidel@...ilserver.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Ingo Molnar <mingo@...e.hu>,
Linus Torvalds <torvalds@...ux-foundation.org>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Roland McGrath <roland@...hat.com>,
Rusty Russell <rusty@...tcorp.com.au>,
linux-kernel@...r.kernel.org, <linux-arch@...r.kernel.org>
Subject: [PATCH] kthread: Enhance kthread_stop to abort interruptible sleeps
This patch reworks kthread_stop so it is more flexible and it causes
the target kthread to abort interruptible sleeps. Allowing a larger
class of kernel threads to use to the kthread API.
The changes start by defining TIF_KTHREAD_STOP on all architectures.
TIF_KTHREAD_STOP is a per process flag that I can set from another
process to indicate that a kernel thread should stop.
wake_up_process in kthread_stop has been replaced by signal_wake_up
ensuring that the kernel thread if sleeping is woken up in a timely
manner and with TIF_SIGNAL_PENDING set, which causes us to break out
of interruptible sleeps.
recalc_signal_pending was modified to keep TIF_SIGNAL_PENDING set for
as long as TIF_KTHREAD_STOP is set.
Arbitrary paths to do_exit are now allowed. I have placed a
completion on the thread stack and pointed vfork_done at it, when the
mm_release is called from do_exit the completion will be called.
Since the completion is stored on the stack it is important that
kthread() now calls do_exit ensuring the stack frame that holds the
completion is never released, and so that our exit_code is certain to
make it unchanged all the way to do_exit.
To allow kthread_stop to read the process exit code when exit_mm wakes
it up I have moved the setting of exit_code to the beginning of
do_exit.
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
include/asm-alpha/thread_info.h | 1 +
include/asm-arm/thread_info.h | 1 +
include/asm-arm26/thread_info.h | 1 +
include/asm-avr32/thread_info.h | 1 +
include/asm-cris/thread_info.h | 1 +
include/asm-frv/thread_info.h | 1 +
include/asm-h8300/thread_info.h | 1 +
include/asm-i386/thread_info.h | 1 +
include/asm-ia64/thread_info.h | 1 +
include/asm-m32r/thread_info.h | 1 +
include/asm-m68k/thread_info.h | 1 +
include/asm-m68knommu/thread_info.h | 1 +
include/asm-mips/thread_info.h | 1 +
include/asm-parisc/thread_info.h | 1 +
include/asm-powerpc/thread_info.h | 1 +
include/asm-s390/thread_info.h | 1 +
include/asm-sh/thread_info.h | 1 +
include/asm-sh64/thread_info.h | 1 +
include/asm-sparc/thread_info.h | 1 +
include/asm-sparc64/thread_info.h | 1 +
include/asm-um/thread_info.h | 1 +
include/asm-v850/thread_info.h | 1 +
include/asm-x86_64/thread_info.h | 1 +
include/asm-xtensa/thread_info.h | 1 +
include/linux/kthread.h | 20 ++++++++-
kernel/exit.c | 2 +-
kernel/kthread.c | 81 ++++++++++++-----------------------
kernel/signal.c | 3 +-
28 files changed, 72 insertions(+), 58 deletions(-)
diff --git a/include/asm-alpha/thread_info.h b/include/asm-alpha/thread_info.h
index 69ffd93..31c41e0 100644
--- a/include/asm-alpha/thread_info.h
+++ b/include/asm-alpha/thread_info.h
@@ -76,6 +76,7 @@ register struct thread_info *__current_thread_info __asm__("$8");
#define TIF_UAC_NOFIX 7
#define TIF_UAC_SIGBUS 8
#define TIF_MEMDIE 9
+#define TIF_KTHREAD_STOP 10
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-arm/thread_info.h b/include/asm-arm/thread_info.h
index 5014794..e6db6f1 100644
--- a/include/asm-arm/thread_info.h
+++ b/include/asm-arm/thread_info.h
@@ -148,6 +148,7 @@ extern void iwmmxt_task_switch(struct thread_info *);
#define TIF_USING_IWMMXT 17
#define TIF_MEMDIE 18
#define TIF_FREEZE 19
+#define TIF_KTHREAD_STOP 20
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
diff --git a/include/asm-arm26/thread_info.h b/include/asm-arm26/thread_info.h
index 9b367eb..614cc8c 100644
--- a/include/asm-arm26/thread_info.h
+++ b/include/asm-arm26/thread_info.h
@@ -123,6 +123,7 @@ extern void free_thread_info(struct thread_info *);
#define TIF_USED_FPU 16
#define TIF_POLLING_NRFLAG 17
#define TIF_MEMDIE 18
+#define TIF_KTHREAD_STOP 19
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
diff --git a/include/asm-avr32/thread_info.h b/include/asm-avr32/thread_info.h
index d1f5b35..2f295de 100644
--- a/include/asm-avr32/thread_info.h
+++ b/include/asm-avr32/thread_info.h
@@ -83,6 +83,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SINGLE_STEP 6 /* single step after next break */
#define TIF_MEMDIE 7
#define TIF_RESTORE_SIGMASK 8 /* restore signal mask in do_signal */
+#define TIF_KTHREAD_STOP 9
#define TIF_USERSPACE 31 /* true if FS sets userspace */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
diff --git a/include/asm-cris/thread_info.h b/include/asm-cris/thread_info.h
index 7ad853c..5076b97 100644
--- a/include/asm-cris/thread_info.h
+++ b/include/asm-cris/thread_info.h
@@ -84,6 +84,7 @@ struct thread_info {
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 17
+#define TIF_KTHREAD_STOP 18
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-frv/thread_info.h b/include/asm-frv/thread_info.h
index d881f51..3bb68c0 100644
--- a/include/asm-frv/thread_info.h
+++ b/include/asm-frv/thread_info.h
@@ -117,6 +117,7 @@ register struct thread_info *__current_thread_info asm("gr15");
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 17 /* OOM killer killed process */
#define TIF_FREEZE 18 /* freezing for suspend */
+#define TIF_KTHREAD_STOP 19
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
diff --git a/include/asm-h8300/thread_info.h b/include/asm-h8300/thread_info.h
index 45f09dc..fda90d3 100644
--- a/include/asm-h8300/thread_info.h
+++ b/include/asm-h8300/thread_info.h
@@ -92,6 +92,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
+#define TIF_KTHREAD_STOP 6
/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h
index 4b187bb..b823054 100644
--- a/include/asm-i386/thread_info.h
+++ b/include/asm-i386/thread_info.h
@@ -135,6 +135,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_DEBUG 17 /* uses debug registers */
#define TIF_IO_BITMAP 18 /* uses I/O bitmap */
#define TIF_FREEZE 19 /* is freezing for suspend */
+#define TIF_KTHREAD_STOP 20
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-ia64/thread_info.h b/include/asm-ia64/thread_info.h
index 9169859..2a5391b 100644
--- a/include/asm-ia64/thread_info.h
+++ b/include/asm-ia64/thread_info.h
@@ -90,6 +90,7 @@ struct thread_info {
#define TIF_MCA_INIT 18 /* this task is processing MCA or INIT */
#define TIF_DB_DISABLED 19 /* debug trap disabled for fsyscall */
#define TIF_FREEZE 20 /* is freezing for suspend */
+#define TIF_KTHREAD_STOP 21
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
diff --git a/include/asm-m32r/thread_info.h b/include/asm-m32r/thread_info.h
index 22aff32..6f06f93 100644
--- a/include/asm-m32r/thread_info.h
+++ b/include/asm-m32r/thread_info.h
@@ -154,6 +154,7 @@ static inline unsigned int get_thread_fault_code(void)
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
/* 31..28 fault code */
#define TIF_MEMDIE 17
+#define TIF_KTHREAD_STOP 18
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-m68k/thread_info.h b/include/asm-m68k/thread_info.h
index c4d622a..3c9d2f2 100644
--- a/include/asm-m68k/thread_info.h
+++ b/include/asm-m68k/thread_info.h
@@ -58,5 +58,6 @@ struct thread_info {
#define TIF_DELAYED_TRACE 14 /* single step a syscall */
#define TIF_SYSCALL_TRACE 15 /* syscall trace active */
#define TIF_MEMDIE 16
+#define TIF_KTHREAD_STOP 17
#endif /* _ASM_M68K_THREAD_INFO_H */
diff --git a/include/asm-m68knommu/thread_info.h b/include/asm-m68knommu/thread_info.h
index b8f009e..95f44c6 100644
--- a/include/asm-m68knommu/thread_info.h
+++ b/include/asm-m68knommu/thread_info.h
@@ -89,6 +89,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
+#define TIF_KTHREAD_STOP 6
/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-mips/thread_info.h b/include/asm-mips/thread_info.h
index 6cf05f4..9c425bf 100644
--- a/include/asm-mips/thread_info.h
+++ b/include/asm-mips/thread_info.h
@@ -120,6 +120,7 @@ register struct thread_info *__current_thread_info __asm__("$28");
#define TIF_MEMDIE 18
#define TIF_FREEZE 19
#define TIF_ALLOW_FP_IN_KERNEL 20
+#define TIF_KTHREAD_STOP 21
#define TIF_SYSCALL_TRACE 31 /* syscall trace active */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-parisc/thread_info.h b/include/asm-parisc/thread_info.h
index 949314c..44706a5 100644
--- a/include/asm-parisc/thread_info.h
+++ b/include/asm-parisc/thread_info.h
@@ -63,6 +63,7 @@ struct thread_info {
#define TIF_32BIT 5 /* 32 bit binary */
#define TIF_MEMDIE 6
#define TIF_RESTORE_SIGMASK 7 /* restore saved signal mask */
+#define TIF_KTHREAD_STOP 8
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
diff --git a/include/asm-powerpc/thread_info.h b/include/asm-powerpc/thread_info.h
index 3f32ca8..6e20084 100644
--- a/include/asm-powerpc/thread_info.h
+++ b/include/asm-powerpc/thread_info.h
@@ -123,6 +123,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NOERROR 14 /* Force successful syscall return */
#define TIF_RESTORE_SIGMASK 15 /* Restore signal mask in do_signal */
#define TIF_FREEZE 16 /* Freezing for suspend */
+#define TIF_KTHREAD_STOP 17
/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-s390/thread_info.h b/include/asm-s390/thread_info.h
index 0a51891..f345e1f 100644
--- a/include/asm-s390/thread_info.h
+++ b/include/asm-s390/thread_info.h
@@ -101,6 +101,7 @@ static inline struct thread_info *current_thread_info(void)
TIF_NEED_RESCHED */
#define TIF_31BIT 18 /* 32bit process */
#define TIF_MEMDIE 19
+#define TIF_KTHREAD_STOP 20
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
diff --git a/include/asm-sh/thread_info.h b/include/asm-sh/thread_info.h
index 31d55e3..8fb5d52 100644
--- a/include/asm-sh/thread_info.h
+++ b/include/asm-sh/thread_info.h
@@ -116,6 +116,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 18
#define TIF_FREEZE 19
+#define TIF_KTHREAD_STOP 20
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-sh64/thread_info.h b/include/asm-sh64/thread_info.h
index 1f825cb..cd7f7c8 100644
--- a/include/asm-sh64/thread_info.h
+++ b/include/asm-sh64/thread_info.h
@@ -78,6 +78,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_MEMDIE 4
+#define TIF_KTHREAD_STOP 5
#endif /* __KERNEL__ */
diff --git a/include/asm-sparc/thread_info.h b/include/asm-sparc/thread_info.h
index 91b9f58..594bce5 100644
--- a/include/asm-sparc/thread_info.h
+++ b/include/asm-sparc/thread_info.h
@@ -137,6 +137,7 @@ BTFIXUPDEF_CALL(void, free_thread_info, struct thread_info *)
#define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling
* TIF_NEED_RESCHED */
#define TIF_MEMDIE 10
+#define TIF_KTHREAD_STOP 11
/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-sparc64/thread_info.h b/include/asm-sparc64/thread_info.h
index 2ebf7f2..3a5178d 100644
--- a/include/asm-sparc64/thread_info.h
+++ b/include/asm-sparc64/thread_info.h
@@ -236,6 +236,7 @@ register struct thread_info *current_thread_info_reg asm("g6");
#define TIF_ABI_PENDING 12
#define TIF_MEMDIE 13
#define TIF_POLLING_NRFLAG 14
+#define TIF_KTHREAD_STOP 15
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
diff --git a/include/asm-um/thread_info.h b/include/asm-um/thread_info.h
index 261e2f4..f10a6ca 100644
--- a/include/asm-um/thread_info.h
+++ b/include/asm-um/thread_info.h
@@ -69,6 +69,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_MEMDIE 5
#define TIF_SYSCALL_AUDIT 6
#define TIF_RESTORE_SIGMASK 7
+#define TIF_KTHREAD_STOP 8
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
diff --git a/include/asm-v850/thread_info.h b/include/asm-v850/thread_info.h
index 82b8f28..98d5922 100644
--- a/include/asm-v850/thread_info.h
+++ b/include/asm-v850/thread_info.h
@@ -83,6 +83,7 @@ struct thread_info {
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
+#define TIF_KTHREAD_STOP 6
/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-x86_64/thread_info.h b/include/asm-x86_64/thread_info.h
index 74a6c74..9ad6545 100644
--- a/include/asm-x86_64/thread_info.h
+++ b/include/asm-x86_64/thread_info.h
@@ -123,6 +123,7 @@ static inline struct thread_info *stack_thread_info(void)
#define TIF_DEBUG 21 /* uses debug registers */
#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
#define TIF_FREEZE 23 /* is freezing for suspend */
+#define TIF_KTHREAD_STOP 24
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-xtensa/thread_info.h b/include/asm-xtensa/thread_info.h
index 5ae34ab..facf5cd 100644
--- a/include/asm-xtensa/thread_info.h
+++ b/include/asm-xtensa/thread_info.h
@@ -117,6 +117,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_IRET 5 /* return with iret */
#define TIF_MEMDIE 6
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
+#define TIF_KTHREAD_STOP 17
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 00dd957..a8ea31d 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -10,7 +10,7 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
/**
* kthread_run - create and wake a thread.
- * @threadfn: the function to run until signal_pending(current).
+ * @threadfn: the function to run until kthread_should_stop().
* @data: data ptr for @threadfn.
* @namefmt: printf-style name for the thread.
*
@@ -28,7 +28,23 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
void kthread_bind(struct task_struct *k, unsigned int cpu);
int kthread_stop(struct task_struct *k);
-int kthread_should_stop(void);
+
+static inline int __kthread_should_stop(struct task_struct *tsk)
+{
+ return test_tsk_thread_flag(tsk, TIF_KTHREAD_STOP);
+}
+
+/**
+ * kthread_should_stop - should this kthread return now?
+ *
+ * When someone calls kthread_stop() on your kthread, it will be woken
+ * and this will return true. You should then return, and your return
+ * value will be passed through to kthread_stop().
+ */
+static inline int kthread_should_stop(void)
+{
+ return __kthread_should_stop(current);
+}
int kthreadd(void *unused);
extern struct task_struct *kthreadd_task;
diff --git a/kernel/exit.c b/kernel/exit.c
index 8024e79..3dad696 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -891,6 +891,7 @@ fastcall NORET_TYPE void do_exit(long code)
}
tsk->flags |= PF_EXITING;
+ tsk->exit_code = code;
if (unlikely(in_atomic()))
printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
@@ -937,7 +938,6 @@ fastcall NORET_TYPE void do_exit(long code)
if (tsk->binfmt)
module_put(tsk->binfmt->module);
- tsk->exit_code = code;
proc_exit_connector(tsk);
exit_task_namespaces(tsk);
exit_notify(tsk);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index df8a8e8..06c7e51 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -33,38 +33,18 @@ struct kthread_create_info
struct list_head list;
};
-struct kthread_stop_info
-{
- struct task_struct *k;
- int err;
- struct completion done;
-};
-
-/* Thread stopping is done by setthing this var: lock serializes
- * multiple kthread_stop calls. */
-static DEFINE_MUTEX(kthread_stop_lock);
-static struct kthread_stop_info kthread_stop_info;
-
-/**
- * kthread_should_stop - should this kthread return now?
- *
- * When someone calls kthread_stop() on your kthread, it will be woken
- * and this will return true. You should then return, and your return
- * value will be passed through to kthread_stop().
- */
-int kthread_should_stop(void)
-{
- return (kthread_stop_info.k == current);
-}
-EXPORT_SYMBOL(kthread_should_stop);
-
static int kthread(void *_create)
{
struct kthread_create_info *create = _create;
+ struct completion done;
int (*threadfn)(void *data);
void *data;
int ret = -EINTR;
+ /* Setup a completion on this thread's stack */
+ init_completion(&done);
+ current->vfork_done = &done;
+
/* Copy data: it's on kthread's stack */
threadfn = create->threadfn;
data = create->data;
@@ -77,12 +57,7 @@ static int kthread(void *_create)
if (!kthread_should_stop())
ret = threadfn(data);
- /* It might have exited on its own, w/o kthread_stop. Check. */
- if (kthread_should_stop()) {
- kthread_stop_info.err = ret;
- complete(&kthread_stop_info.done);
- }
- return 0;
+ do_exit(ret);
}
static void create_kthread(struct kthread_create_info *create)
@@ -104,7 +79,7 @@ static void create_kthread(struct kthread_create_info *create)
/**
* kthread_create - create a kthread.
- * @threadfn: the function to run until signal_pending(current).
+ * @threadfn: the function to run until kthread_should_stop().
* @data: data ptr for @threadfn.
* @namefmt: printf-style name for the thread.
*
@@ -174,38 +149,36 @@ EXPORT_SYMBOL(kthread_bind);
* kthread_stop - stop a thread created by kthread_create().
* @k: thread created by kthread_create().
*
- * Sets kthread_should_stop() for @k to return true, wakes it, and
- * waits for it to exit. Your threadfn() must not call do_exit()
- * itself if you use this function! This can also be called after
- * kthread_create() instead of calling wake_up_process(): the thread
- * will exit without calling threadfn().
+ * Sets TIF_KTHREAD_STOP for @k, wakes it and waits for it to exit.
+ *
+ * kthread_stop should be called exactly once on @k.
+ *
+ * This can also be called after kthread_create() instead of calling
+ * wake_up_process(): the thread will exit without calling threadfn().
+ *
+ * If your threadfn may terminate before you call kthread_stop
+ * you should call get_task_struct on @k so it is valid when you call
+ * kthread_stop.
*
* Returns the result of threadfn(), or %-EINTR if wake_up_process()
* was never called.
*/
-int kthread_stop(struct task_struct *k)
+int kthread_stop(struct task_struct *tsk)
{
int ret;
- mutex_lock(&kthread_stop_lock);
-
- /* It could exit after stop_info.k set, but before wake_up_process. */
- get_task_struct(k);
+ /* Ensure the task struct persists until I read the exit code. */
+ get_task_struct(tsk);
- /* Must init completion *before* thread sees kthread_stop_info.k */
- init_completion(&kthread_stop_info.done);
- smp_wmb();
+ set_tsk_thread_flag(tsk, TIF_KTHREAD_STOP);
+ spin_lock_irq(&tsk->sighand->siglock);
+ signal_wake_up(tsk, 1);
+ spin_unlock_irq(&tsk->sighand->siglock);
- /* Now set kthread_should_stop() to true, and wake it up. */
- kthread_stop_info.k = k;
- wake_up_process(k);
- put_task_struct(k);
+ wait_for_completion(tsk->vfork_done);
+ ret = tsk->exit_code;
- /* Once it dies, reset stop ptr, gather result and we're done. */
- wait_for_completion(&kthread_stop_info.done);
- kthread_stop_info.k = NULL;
- ret = kthread_stop_info.err;
- mutex_unlock(&kthread_stop_lock);
+ put_task_struct(tsk);
return ret;
}
diff --git a/kernel/signal.c b/kernel/signal.c
index 2d437f6..fca2a45 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -26,6 +26,7 @@
#include <linux/freezer.h>
#include <linux/pid_namespace.h>
#include <linux/nsproxy.h>
+#include <linux/kthread.h>
#include <asm/param.h>
#include <asm/uaccess.h>
@@ -218,7 +219,7 @@ static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
fastcall void recalc_sigpending_tsk(struct task_struct *t)
{
if (t->signal->group_stop_count > 0 ||
- (freezing(t)) ||
+ (freezing(t)) || __kthread_should_stop(t) ||
PENDING(&t->pending, &t->blocked) ||
PENDING(&t->signal->shared_pending, &t->blocked))
set_tsk_thread_flag(t, TIF_SIGPENDING);
--
1.5.0.g53756
-
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