Messages in this thread Patch in this message | | | Date | Tue, 15 Jun 2021 23:50:05 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] freezer,sched: Rewrite core freezer logic |
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On Tue, Jun 15, 2021 at 05:45:39PM +0200, Oleg Nesterov wrote: > On 06/14, Peter Zijlstra wrote: > > > > One more thing; if I add additional state bits to preserve > > __TASK_{TRACED,STOPPED}, then I need to figure out at thaw time if we've > > missed a wakeup or not. > > > > Do we have sufficient state for that? If so, don't we then also not have > > sufficient state to tell if a task should've been TRACED/STOPPED in the > > first place? > > Not sure I understand you, probably not, but I think the answer is "no" ;)
I was thinking something like the below, such that we can then write something like:
void __thaw_special(struct task_struct *p) { spin_lock(&t->sighand->siglock);
if (p->ptrace) { unsigned int state = __TASK_TRACED;
if (!(p->ptrace & PT_STOPPED)) goto unlock;
if (p->ptrace & PT_STOPPED_FATAL) { state |= TASK_WAKEKILL; if (__fatal_signal_pending(p)) goto unlock; }
set_special_state(state);
} else if ((p->jobctl & JOBCTL_STOP_PENDING) && !__fatal_signal_pending(p)) {
set_special_state(TASK_STOPPED); }
unlock: spin_unlock(&t->sighand->siglock); }
--- diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index b5ebf6c01292..2123d6543125 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -28,30 +28,36 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr, * flags. When the a task is stopped the ptracer owns task->ptrace. */ -#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */ -#define PT_PTRACED 0x00000001 -#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ +#define PT_PTRACED 0x00000001 // 0x00000001 +#define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ // 0x00000002 #define PT_OPT_FLAG_SHIFT 3 /* PT_TRACE_* event enable flags */ #define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event))) -#define PT_TRACESYSGOOD PT_EVENT_FLAG(0) -#define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK) -#define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK) -#define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE) -#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) -#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) -#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) -#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP) - -#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT) -#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT) + +#define PT_TRACESYSGOOD PT_EVENT_FLAG(0) // 0x00000008 +#define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK) // 0x00000010 +#define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK) // 0x00000020 +#define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE) // 0x00000040 +#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) // 0x00000080 +#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) // 0x00000100 +#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) // 0x00000200 +#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP) // 0x00000400 + +#define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */// 0x00010000 +#define PT_STOPPED 0x00020000 // 0x00020000 +#define PT_STOPPED_FATAL 0x00040000 // 0x00040000 + +#define PT_STOPPED_MASK (PT_STOPPED|PT_STOPPED_FATAL) + +#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT) // 0x00800000 +#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT) // 0x01000000 /* single stepping state bits (used on ARM and PA-RISC) */ #define PT_SINGLESTEP_BIT 31 -#define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT) +#define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT) // 0x80000000 #define PT_BLOCKSTEP_BIT 30 -#define PT_BLOCKSTEP (1<<PT_BLOCKSTEP_BIT) +#define PT_BLOCKSTEP (1<<PT_BLOCKSTEP_BIT) // 0x40000000 extern long arch_ptrace(struct task_struct *child, long request, unsigned long addr, unsigned long data); diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 0d7fec79d28f..0cf806030bfd 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -424,6 +424,8 @@ static inline void signal_wake_up(struct task_struct *t, bool resume) } static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume) { + if (resume) + t->ptrace &= ~PT_STOPPED_MASK; signal_wake_up_state(t, resume ? __TASK_TRACED : 0); } diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 2997ca600d18..4fc4e1f91ecd 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -197,6 +197,8 @@ static bool ptrace_freeze_traced(struct task_struct *task) spin_lock_irq(&task->sighand->siglock); if (task_is_traced(task) && !looks_like_a_spurious_pid(task) && !__fatal_signal_pending(task)) { + task->ptrace &= ~PT_STOPPED_MASK; + task->ptrace |= PT_STOPPED; task->state = __TASK_TRACED; ret = true; } @@ -218,10 +220,13 @@ static void ptrace_unfreeze_traced(struct task_struct *task) */ spin_lock_irq(&task->sighand->siglock); if (task->state == __TASK_TRACED) { - if (__fatal_signal_pending(task)) + if (__fatal_signal_pending(task)) { + task->ptrace &= ~PT_STOPPED_MASK; wake_up_state(task, __TASK_TRACED); - else + } else { + task->ptrace |= PT_STOPPED_MASK; task->state = TASK_TRACED; + } } spin_unlock_irq(&task->sighand->siglock); } @@ -835,8 +840,6 @@ static long ptrace_get_rseq_configuration(struct task_struct *task, static int ptrace_resume(struct task_struct *child, long request, unsigned long data) { - bool need_siglock; - if (!valid_signal(data)) return -EIO; @@ -877,13 +880,11 @@ static int ptrace_resume(struct task_struct *child, long request, * status and clears the code too; this can't race with the tracee, it * takes siglock after resume. */ - need_siglock = data && !thread_group_empty(current); - if (need_siglock) - spin_lock_irq(&child->sighand->siglock); + spin_lock_irq(&child->sighand->siglock); child->exit_code = data; + child->ptrace &= ~PT_STOPPED_MASK; wake_up_state(child, __TASK_TRACED); - if (need_siglock) - spin_unlock_irq(&child->sighand->siglock); + spin_unlock_irq(&child->sighand->siglock); return 0; } diff --git a/kernel/signal.c b/kernel/signal.c index f7c6ffcbd044..35cdb92b7f1d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2195,6 +2195,7 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t return; } + current->ptrace |= PT_STOPPED_MASK; set_special_state(TASK_TRACED); /*
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