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Subject[swsusp] swsusp process freezing: remove smp races
From: Christoph Lameter <christoph@lameter.com>

The current suspend code modifies thread->flags from outside the
context of the thread. This creates a SMP race.

This patch fixes that by introducing a TIF_FREEZE flag in thread_info.

(This is not the end of the races in the suspend code since TIF_FREEZE
is cleared when setting PF_FROZEN creating a window for
freeze_processes(). OTOH, this patch actually works :-)

Signed-off-by: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Pavel Machek <pavel@suse.cz>

---
commit b3ace94a1a465a2084bed642021aa8c8ddd912d1
tree 479de81d32de97f456f5d2929597f4047e1aab6f
parent e83468048173e800bfc4dc09c2d609f9983cd29d
author <pavel@amd.(none)> Mon, 18 Jul 2005 22:20:46 +0200
committer <pavel@amd.(none)> Mon, 18 Jul 2005 22:20:46 +0200

include/asm-alpha/thread_info.h | 1 +
include/asm-arm/thread_info.h | 1 +
include/asm-arm26/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-ppc/thread_info.h | 1 +
include/asm-ppc64/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/sched.h | 9 ++++-----
25 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/include/asm-alpha/thread_info.h b/include/asm-alpha/thread_info.h
--- a/include/asm-alpha/thread_info.h
+++ b/include/asm-alpha/thread_info.h
@@ -78,6 +78,7 @@ register struct thread_info *__current_t
#define TIF_UAC_NOFIX 7
#define TIF_UAC_SIGBUS 8
#define TIF_MEMDIE 9
+#define TIF_FREEZE 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
--- a/include/asm-arm/thread_info.h
+++ b/include/asm-arm/thread_info.h
@@ -132,6 +132,7 @@ extern void iwmmxt_task_release(struct t
#define TIF_POLLING_NRFLAG 16
#define TIF_USING_IWMMXT 17
#define TIF_MEMDIE 18
+#define TIF_FREEZE 19

#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
--- a/include/asm-arm26/thread_info.h
+++ b/include/asm-arm26/thread_info.h
@@ -127,6 +127,7 @@ extern void free_thread_info(struct thre
#define TIF_USED_FPU 16
#define TIF_POLLING_NRFLAG 17
#define TIF_MEMDIE 18
+#define TIF_FREEZE 19

#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
diff --git a/include/asm-cris/thread_info.h b/include/asm-cris/thread_info.h
--- a/include/asm-cris/thread_info.h
+++ b/include/asm-cris/thread_info.h
@@ -86,6 +86,7 @@ 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_FREEZE 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
--- a/include/asm-frv/thread_info.h
+++ b/include/asm-frv/thread_info.h
@@ -133,6 +133,7 @@ register struct thread_info *__current_t
#define TIF_IRET 5 /* return with iret */
#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

#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
--- a/include/asm-h8300/thread_info.h
+++ b/include/asm-h8300/thread_info.h
@@ -94,6 +94,7 @@ static inline struct thread_info *curren
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
+#define TIF_FREEZE 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
--- a/include/asm-i386/thread_info.h
+++ b/include/asm-i386/thread_info.h
@@ -143,6 +143,7 @@ register unsigned long current_stack_poi
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 17
+#define TIF_FREEZE 18 /* Freeze thread */

#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
--- a/include/asm-ia64/thread_info.h
+++ b/include/asm-ia64/thread_info.h
@@ -76,6 +76,7 @@ struct thread_info {
#define TIF_SIGDELAYED 5 /* signal delayed from MCA/INIT/NMI/PMI context */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 17
+#define TIF_FREEZE 18 /* Freeze process */

#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
--- a/include/asm-m32r/thread_info.h
+++ b/include/asm-m32r/thread_info.h
@@ -156,6 +156,7 @@ static inline unsigned int get_thread_fa
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
/* 31..28 fault code */
#define TIF_MEMDIE 17
+#define TIF_FREEZE 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
--- a/include/asm-m68k/thread_info.h
+++ b/include/asm-m68k/thread_info.h
@@ -49,6 +49,7 @@ struct thread_info {
#define TIF_SIGPENDING 3 /* signal pending */
#define TIF_NEED_RESCHED 4 /* rescheduling necessary */
#define TIF_MEMDIE 5
+#define TIF_FREEZE 6

extern int thread_flag_fixme(void);

diff --git a/include/asm-m68knommu/thread_info.h b/include/asm-m68knommu/thread_info.h
--- a/include/asm-m68knommu/thread_info.h
+++ b/include/asm-m68knommu/thread_info.h
@@ -91,6 +91,7 @@ static inline struct thread_info *curren
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
+#define TIF_FREEZE 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
--- a/include/asm-mips/thread_info.h
+++ b/include/asm-mips/thread_info.h
@@ -117,6 +117,7 @@ register struct thread_info *__current_t
#define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 18
+#define TIF_FREEZE 19
#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
--- a/include/asm-parisc/thread_info.h
+++ b/include/asm-parisc/thread_info.h
@@ -64,6 +64,7 @@ struct thread_info {
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_32BIT 5 /* 32 bit binary */
#define TIF_MEMDIE 6
+#define TIF_FREEZE 7

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
diff --git a/include/asm-ppc/thread_info.h b/include/asm-ppc/thread_info.h
--- a/include/asm-ppc/thread_info.h
+++ b/include/asm-ppc/thread_info.h
@@ -80,6 +80,7 @@ static inline struct thread_info *curren
#define TIF_MEMDIE 5
#define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */
#define TIF_SECCOMP 7 /* secure computing */
+#define TIF_FREEZE 8

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-ppc64/thread_info.h b/include/asm-ppc64/thread_info.h
--- a/include/asm-ppc64/thread_info.h
+++ b/include/asm-ppc64/thread_info.h
@@ -102,6 +102,7 @@ static inline struct thread_info *curren
#define TIF_SINGLESTEP 9 /* singlestepping active */
#define TIF_MEMDIE 10
#define TIF_SECCOMP 11 /* secure computing */
+#define TIF_FREEZE 12

/* 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
--- a/include/asm-s390/thread_info.h
+++ b/include/asm-s390/thread_info.h
@@ -102,6 +102,7 @@ static inline struct thread_info *curren
TIF_NEED_RESCHED */
#define TIF_31BIT 18 /* 32bit process */
#define TIF_MEMDIE 19
+#define TIF_FREEZE 20

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-sh/thread_info.h b/include/asm-sh/thread_info.h
--- a/include/asm-sh/thread_info.h
+++ b/include/asm-sh/thread_info.h
@@ -84,6 +84,7 @@ static inline struct thread_info *curren
#define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 18
+#define TIF_FREEZE 19
#define TIF_USERSPACE 31 /* true if FS sets userspace */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/asm-sh64/thread_info.h b/include/asm-sh64/thread_info.h
--- a/include/asm-sh64/thread_info.h
+++ b/include/asm-sh64/thread_info.h
@@ -80,6 +80,7 @@ static inline struct thread_info *curren
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_MEMDIE 4
+#define TIF_FREEZE 5


#endif /* __KERNEL__ */
diff --git a/include/asm-sparc/thread_info.h b/include/asm-sparc/thread_info.h
--- a/include/asm-sparc/thread_info.h
+++ b/include/asm-sparc/thread_info.h
@@ -139,6 +139,7 @@ BTFIXUPDEF_CALL(void, free_thread_info,
#define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling
* TIF_NEED_RESCHED */
#define TIF_MEMDIE 10
+#define TIF_FREEZE 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
--- a/include/asm-sparc64/thread_info.h
+++ b/include/asm-sparc64/thread_info.h
@@ -230,6 +230,7 @@ register struct thread_info *current_thr
#define TIF_ABI_PENDING 12
#define TIF_MEMDIE 13
#define TIF_POLLING_NRFLAG 14
+#define TIF_FREEZE 15

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
diff --git a/include/asm-um/thread_info.h b/include/asm-um/thread_info.h
--- a/include/asm-um/thread_info.h
+++ b/include/asm-um/thread_info.h
@@ -72,6 +72,7 @@ static inline struct thread_info *curren
#define TIF_RESTART_BLOCK 4
#define TIF_MEMDIE 5
#define TIF_SYSCALL_AUDIT 6
+#define TIF_FREEZE 7

#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
--- a/include/asm-v850/thread_info.h
+++ b/include/asm-v850/thread_info.h
@@ -85,6 +85,7 @@ struct thread_info {
#define TIF_POLLING_NRFLAG 4 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
+#define TIF_FREEZE 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
--- a/include/asm-x86_64/thread_info.h
+++ b/include/asm-x86_64/thread_info.h
@@ -108,6 +108,7 @@ static inline struct thread_info *stack_
#define TIF_FORK 18 /* ret_from_fork */
#define TIF_ABI_PENDING 19
#define TIF_MEMDIE 20
+#define TIF_FREEZE 21 /* Freeze process */

#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
--- a/include/asm-xtensa/thread_info.h
+++ b/include/asm-xtensa/thread_info.h
@@ -118,6 +118,7 @@ static inline struct thread_info *curren
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_IRET 5 /* return with iret */
#define TIF_MEMDIE 6
+#define TIF_FREEZE 7
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
diff --git a/include/linux/sched.h b/include/linux/sched.h
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -811,7 +811,6 @@ do { if (atomic_dec_and_test(&(tsk)->usa
#define PF_MEMALLOC 0x00000800 /* Allocating memory */
#define PF_FLUSHER 0x00001000 /* responsible for disk writeback */
#define PF_USED_MATH 0x00002000 /* if unset the fpu must be initialized before use */
-#define PF_FREEZE 0x00004000 /* this task is being frozen for suspend now */
#define PF_NOFREEZE 0x00008000 /* this thread should not be frozen */
#define PF_FROZEN 0x00010000 /* frozen for system suspend */
#define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */
@@ -1287,16 +1286,15 @@ static inline int frozen(struct task_str
*/
static inline int freezing(struct task_struct *p)
{
- return p->flags & PF_FREEZE;
+ return test_ti_thread_flag(p->thread_info, TIF_FREEZE);
}

/*
* Request that a process be frozen
- * FIXME: SMP problem. We may not modify other process' flags!
*/
static inline void freeze(struct task_struct *p)
{
- p->flags |= PF_FREEZE;
+ set_ti_thread_flag(p->thread_info, TIF_FREEZE);
}

/*
@@ -1317,7 +1315,8 @@ static inline int thaw_process(struct ta
*/
static inline void frozen_process(struct task_struct *p)
{
- p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN;
+ p->flags |= PF_FROZEN;
+ clear_ti_thread_flag(p->thread_info, TIF_FREEZE);
}

extern void refrigerator(void);
--
teflon -- maybe it is a trademark, but it should not be.
-
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