From 81d68a96a39844853b37f20cc8282d9b65b78ef3 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 12 May 2008 21:20:42 +0200 Subject: ftrace: trace irq disabled critical timings This patch adds latency tracing for critical timings (how long interrupts are disabled for). "irqsoff" is added to /debugfs/tracing/available_tracers Note: tracing_max_latency also holds the max latency for irqsoff (in usecs). (default to large number so one must start latency tracing) tracing_thresh threshold (in usecs) to always print out if irqs off is detected to be longer than stated here. If irq_thresh is non-zero, then max_irq_latency is ignored. Here's an example of a trace with ftrace_enabled = 0 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 Signed-off-by: Ingo Molnar -------------------------------------------------------------------- latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1d.s3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1d.s3 100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1d.s3 100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= And this is a trace with ftrace_enabled == 1 ======= preemption latency trace v1.1.5 on 2.6.24-rc7 -------------------------------------------------------------------- latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2) ----------------- | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0) ----------------- => started at: _spin_lock_irqsave+0x2a/0xb7 => ended at: _spin_unlock_irqrestore+0x32/0x5f _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / swapper-0 1dNs3 0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000]) swapper-0 1dNs3 46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000]) swapper-0 1dNs3 46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000]) swapper-0 1dNs3 47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000]) swapper-0 1dNs3 47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47) swapper-0 1dNs3 97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50) swapper-0 1dNs3 98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000]) swapper-0 1dNs3 99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000]) swapper-0 1dNs3 101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000]) swapper-0 1dNs3 102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f) vim:ft=help ======= Signed-off-by: Steven Rostedt Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- kernel/fork.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 19908b26cf8..d66d676dc36 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -909,7 +909,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, rt_mutex_init_task(p); -#ifdef CONFIG_TRACE_IRQFLAGS +#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_LOCKDEP) DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); #endif -- cgit v1.2.3-70-g09d2 From da9cbc87395308a21465bd25441297bbba0477e1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 30 Jun 2008 20:42:08 +0200 Subject: block: blkdev.h cleanup, move iocontext stuff to iocontext.h Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 17 ----------------- include/linux/iocontext.h | 18 ++++++++++++++++++ kernel/exit.c | 1 + kernel/fork.c | 1 + 4 files changed, 20 insertions(+), 17 deletions(-) (limited to 'kernel/fork.c') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 4a9ed45270f..443df75d2cd 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -33,12 +33,6 @@ struct sg_io_hdr; #define BLKDEV_MIN_RQ 4 #define BLKDEV_MAX_RQ 128 /* Default maximum */ -int put_io_context(struct io_context *ioc); -void exit_io_context(void); -struct io_context *get_io_context(gfp_t gfp_flags, int node); -struct io_context *alloc_io_context(gfp_t gfp_flags, int node); -void copy_io_context(struct io_context **pdst, struct io_context **psrc); - struct request; typedef void (rq_end_io_fn)(struct request *, int); @@ -981,17 +975,6 @@ static inline long nr_blockdev_pages(void) return 0; } -static inline void exit_io_context(void) -{ -} - -struct io_context; -static inline int put_io_context(struct io_context *ioc) -{ - return 1; -} - - #endif /* CONFIG_BLOCK */ #endif diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index 2b7a1187cb2..08b987bccf8 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -99,4 +99,22 @@ static inline struct io_context *ioc_task_link(struct io_context *ioc) return NULL; } +#ifdef CONFIG_BLOCK +int put_io_context(struct io_context *ioc); +void exit_io_context(void); +struct io_context *get_io_context(gfp_t gfp_flags, int node); +struct io_context *alloc_io_context(gfp_t gfp_flags, int node); +void copy_io_context(struct io_context **pdst, struct io_context **psrc); +#else +static inline void exit_io_context(void) +{ +} + +struct io_context; +static inline int put_io_context(struct io_context *ioc) +{ + return 1; +} +#endif + #endif diff --git a/kernel/exit.c b/kernel/exit.c index 8f6185e69b6..ceb25878283 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include diff --git a/kernel/fork.c b/kernel/fork.c index 19908b26cf8..b71ccd09fc8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include #include -- cgit v1.2.3-70-g09d2 From d12c1a37925a8ec386994169605fe99217295199 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 14 Jul 2008 12:09:28 +0200 Subject: lockdep: fix kernel/fork.c warning fix: [ 0.184011] ------------[ cut here ]------------ [ 0.188011] WARNING: at kernel/fork.c:918 copy_process+0x1c0/0x1084() [ 0.192011] Pid: 0, comm: swapper Not tainted 2.6.26-tip-00351-g01d4a50-dirty #14521 [ 0.196011] [] warn_on_slowpath+0x3c/0x60 [ 0.200012] [] ? __alloc_pages_internal+0x92/0x36b [ 0.208012] [] ? __spin_lock_init+0x24/0x4a [ 0.212012] [] copy_process+0x1c0/0x1084 [ 0.216013] [] do_fork+0xb8/0x1ad [ 0.220013] [] ? acpi_os_release_lock+0x8/0xa [ 0.228013] [] ? acpi_os_vprintf+0x20/0x24 [ 0.232014] [] kernel_thread+0x75/0x7d [ 0.236014] [] ? kernel_init+0x0/0x24a [ 0.240014] [] ? kernel_init+0x0/0x24a [ 0.244014] [] ? kernel_thread_helper+0x0/0x10 [ 0.252015] [] rest_init+0x14/0x50 [ 0.256015] [] start_kernel+0x2b9/0x2c0 [ 0.260015] [] __init_begin+0x4f/0x57 [ 0.264016] ======================= [ 0.268016] ---[ end trace 4eaa2a86a8e2da22 ]--- [ 0.272016] enabled ExtINT on CPU#0 which occurs if CONFIG_TRACE_IRQFLAGS=y, CONFIG_DEBUG_LOCKDEP=y, but CONFIG_PROVE_LOCKING is disabled. Signed-off-by: Ingo Molnar --- kernel/fork.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 19908b26cf8..cdb1f82d3bd 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -909,7 +909,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, rt_mutex_init_task(p); -#ifdef CONFIG_TRACE_IRQFLAGS +#ifdef CONFIG_PROVE_LOCKING DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); #endif -- cgit v1.2.3-70-g09d2 From f470021adb9190819c03d6d8c5c860a17480aa6d Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Mon, 24 Mar 2008 18:36:23 -0700 Subject: ptrace children revamp ptrace no longer fiddles with the children/sibling links, and the old ptrace_children list is gone. Now ptrace, whether of one's own children or another's via PTRACE_ATTACH, just uses the new ptraced list instead. There should be no user-visible difference that matters. The only change is the order in which do_wait() sees multiple stopped children and stopped ptrace attachees. Since wait_task_stopped() was changed earlier so it no longer reorders the children list, we already know this won't cause any new problems. Signed-off-by: Roland McGrath --- include/linux/init_task.h | 4 +- include/linux/sched.h | 26 +++--- kernel/exit.c | 226 ++++++++++++++++++++++++---------------------- kernel/fork.c | 6 +- kernel/ptrace.c | 37 +++++--- 5 files changed, 160 insertions(+), 139 deletions(-) (limited to 'kernel/fork.c') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 9927a88674a..93c45acf249 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -140,8 +140,8 @@ extern struct group_info init_groups; .nr_cpus_allowed = NR_CPUS, \ }, \ .tasks = LIST_HEAD_INIT(tsk.tasks), \ - .ptrace_children= LIST_HEAD_INIT(tsk.ptrace_children), \ - .ptrace_list = LIST_HEAD_INIT(tsk.ptrace_list), \ + .ptraced = LIST_HEAD_INIT(tsk.ptraced), \ + .ptrace_entry = LIST_HEAD_INIT(tsk.ptrace_entry), \ .real_parent = &tsk, \ .parent = &tsk, \ .children = LIST_HEAD_INIT(tsk.children), \ diff --git a/include/linux/sched.h b/include/linux/sched.h index ba2f859c6e4..1941d8b5cf1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1062,12 +1062,6 @@ struct task_struct { #endif struct list_head tasks; - /* - * ptrace_list/ptrace_children forms the list of my children - * that were stolen by a ptracer. - */ - struct list_head ptrace_children; - struct list_head ptrace_list; struct mm_struct *mm, *active_mm; @@ -1089,18 +1083,25 @@ struct task_struct { /* * pointers to (original) parent process, youngest child, younger sibling, * older sibling, respectively. (p->father can be replaced with - * p->parent->pid) + * p->real_parent->pid) */ - struct task_struct *real_parent; /* real parent process (when being debugged) */ - struct task_struct *parent; /* parent process */ + struct task_struct *real_parent; /* real parent process */ + struct task_struct *parent; /* recipient of SIGCHLD, wait4() reports */ /* - * children/sibling forms the list of my children plus the - * tasks I'm ptracing. + * children/sibling forms the list of my natural children */ struct list_head children; /* list of my children */ struct list_head sibling; /* linkage in my parent's children list */ struct task_struct *group_leader; /* threadgroup leader */ + /* + * ptraced is the list of tasks this task is using ptrace on. + * This includes both natural children and PTRACE_ATTACH targets. + * p->ptrace_entry is p's link on the p->parent->ptraced list. + */ + struct list_head ptraced; + struct list_head ptrace_entry; + /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; @@ -1876,9 +1877,6 @@ extern void wait_task_inactive(struct task_struct * p); #define wait_task_inactive(p) do { } while (0) #endif -#define remove_parent(p) list_del_init(&(p)->sibling) -#define add_parent(p) list_add_tail(&(p)->sibling,&(p)->parent->children) - #define next_task(p) list_entry(rcu_dereference((p)->tasks.next), struct task_struct, tasks) #define for_each_process(p) \ diff --git a/kernel/exit.c b/kernel/exit.c index 7453356a961..1e909826a80 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -71,7 +71,7 @@ static void __unhash_process(struct task_struct *p) __get_cpu_var(process_counts)--; } list_del_rcu(&p->thread_group); - remove_parent(p); + list_del_init(&p->sibling); } /* @@ -152,6 +152,18 @@ static void delayed_put_task_struct(struct rcu_head *rhp) put_task_struct(container_of(rhp, struct task_struct, rcu)); } +/* + * Do final ptrace-related cleanup of a zombie being reaped. + * + * Called with write_lock(&tasklist_lock) held. + */ +static void ptrace_release_task(struct task_struct *p) +{ + BUG_ON(!list_empty(&p->ptraced)); + ptrace_unlink(p); + BUG_ON(!list_empty(&p->ptrace_entry)); +} + void release_task(struct task_struct * p) { struct task_struct *leader; @@ -160,8 +172,7 @@ repeat: atomic_dec(&p->user->processes); proc_flush_task(p); write_lock_irq(&tasklist_lock); - ptrace_unlink(p); - BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children)); + ptrace_release_task(p); __exit_signal(p); /* @@ -315,9 +326,8 @@ static void reparent_to_kthreadd(void) ptrace_unlink(current); /* Reparent to init */ - remove_parent(current); current->real_parent = current->parent = kthreadd_task; - add_parent(current); + list_move_tail(¤t->sibling, ¤t->real_parent->children); /* Set the exit signal to SIGCHLD so we signal init on exit */ current->exit_signal = SIGCHLD; @@ -692,37 +702,71 @@ static void exit_mm(struct task_struct * tsk) mmput(mm); } -static void -reparent_thread(struct task_struct *p, struct task_struct *father, int traced) +/* + * Detach all tasks we were using ptrace on. + * Any that need to be release_task'd are put on the @dead list. + * + * Called with write_lock(&tasklist_lock) held. + */ +static void ptrace_exit(struct task_struct *parent, struct list_head *dead) { - if (p->pdeath_signal) - /* We already hold the tasklist_lock here. */ - group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); + struct task_struct *p, *n; - /* Move the child from its dying parent to the new one. */ - if (unlikely(traced)) { - /* Preserve ptrace links if someone else is tracing this child. */ - list_del_init(&p->ptrace_list); - if (ptrace_reparented(p)) - list_add(&p->ptrace_list, &p->real_parent->ptrace_children); - } else { - /* If this child is being traced, then we're the one tracing it - * anyway, so let go of it. + list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) { + __ptrace_unlink(p); + + if (p->exit_state != EXIT_ZOMBIE) + continue; + + /* + * If it's a zombie, our attachedness prevented normal + * parent notification or self-reaping. Do notification + * now if it would have happened earlier. If it should + * reap itself, add it to the @dead list. We can't call + * release_task() here because we already hold tasklist_lock. + * + * If it's our own child, there is no notification to do. */ - p->ptrace = 0; - remove_parent(p); - p->parent = p->real_parent; - add_parent(p); + if (!task_detached(p) && thread_group_empty(p)) { + if (!same_thread_group(p->real_parent, parent)) + do_notify_parent(p, p->exit_signal); + } - if (task_is_traced(p)) { + if (task_detached(p)) { /* - * If it was at a trace stop, turn it into - * a normal stop since it's no longer being - * traced. + * Mark it as in the process of being reaped. */ - ptrace_untrace(p); + p->exit_state = EXIT_DEAD; + list_add(&p->ptrace_entry, dead); } } +} + +/* + * Finish up exit-time ptrace cleanup. + * + * Called without locks. + */ +static void ptrace_exit_finish(struct task_struct *parent, + struct list_head *dead) +{ + struct task_struct *p, *n; + + BUG_ON(!list_empty(&parent->ptraced)); + + list_for_each_entry_safe(p, n, dead, ptrace_entry) { + list_del_init(&p->ptrace_entry); + release_task(p); + } +} + +static void reparent_thread(struct task_struct *p, struct task_struct *father) +{ + if (p->pdeath_signal) + /* We already hold the tasklist_lock here. */ + group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p); + + list_move_tail(&p->sibling, &p->real_parent->children); /* If this is a threaded reparent there is no need to * notify anyone anything has happened. @@ -737,7 +781,8 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced) /* If we'd notified the old parent about this child's death, * also notify the new parent. */ - if (!traced && p->exit_state == EXIT_ZOMBIE && + if (!ptrace_reparented(p) && + p->exit_state == EXIT_ZOMBIE && !task_detached(p) && thread_group_empty(p)) do_notify_parent(p, p->exit_signal); @@ -754,12 +799,15 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced) static void forget_original_parent(struct task_struct *father) { struct task_struct *p, *n, *reaper = father; - struct list_head ptrace_dead; - - INIT_LIST_HEAD(&ptrace_dead); + LIST_HEAD(ptrace_dead); write_lock_irq(&tasklist_lock); + /* + * First clean up ptrace if we were using it. + */ + ptrace_exit(father, &ptrace_dead); + do { reaper = next_thread(reaper); if (reaper == father) { @@ -768,58 +816,19 @@ static void forget_original_parent(struct task_struct *father) } } while (reaper->flags & PF_EXITING); - /* - * There are only two places where our children can be: - * - * - in our child list - * - in our ptraced child list - * - * Search them and reparent children. - */ list_for_each_entry_safe(p, n, &father->children, sibling) { - int ptrace; - - ptrace = p->ptrace; - - /* if father isn't the real parent, then ptrace must be enabled */ - BUG_ON(father != p->real_parent && !ptrace); - - if (father == p->real_parent) { - /* reparent with a reaper, real father it's us */ - p->real_parent = reaper; - reparent_thread(p, father, 0); - } else { - /* reparent ptraced task to its real parent */ - __ptrace_unlink (p); - if (p->exit_state == EXIT_ZOMBIE && !task_detached(p) && - thread_group_empty(p)) - do_notify_parent(p, p->exit_signal); - } - - /* - * if the ptraced child is a detached zombie we must collect - * it before we exit, or it will remain zombie forever since - * we prevented it from self-reap itself while it was being - * traced by us, to be able to see it in wait4. - */ - if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && task_detached(p))) - list_add(&p->ptrace_list, &ptrace_dead); - } - - list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) { p->real_parent = reaper; - reparent_thread(p, father, 1); + if (p->parent == father) { + BUG_ON(p->ptrace); + p->parent = p->real_parent; + } + reparent_thread(p, father); } write_unlock_irq(&tasklist_lock); BUG_ON(!list_empty(&father->children)); - BUG_ON(!list_empty(&father->ptrace_children)); - - list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) { - list_del_init(&p->ptrace_list); - release_task(p); - } + ptrace_exit_finish(father, &ptrace_dead); } /* @@ -1180,13 +1189,6 @@ static int eligible_child(enum pid_type type, struct pid *pid, int options, return 0; } - /* - * Do not consider detached threads that are - * not ptraced: - */ - if (task_detached(p) && !p->ptrace) - return 0; - /* Wait for all children (clone and not) if __WALL is set; * otherwise, wait for clone children *only* if __WCLONE is * set; otherwise, wait for non-clone children *only*. (Note: @@ -1399,7 +1401,7 @@ static int wait_task_zombie(struct task_struct *p, int options, * the lock and this task is uninteresting. If we return nonzero, we have * released the lock and the system call should return. */ -static int wait_task_stopped(struct task_struct *p, +static int wait_task_stopped(int ptrace, struct task_struct *p, int options, struct siginfo __user *infop, int __user *stat_addr, struct rusage __user *ru) { @@ -1407,7 +1409,7 @@ static int wait_task_stopped(struct task_struct *p, uid_t uid = 0; /* unneeded, required by compiler */ pid_t pid; - if (!(p->ptrace & PT_PTRACED) && !(options & WUNTRACED)) + if (!(options & WUNTRACED)) return 0; exit_code = 0; @@ -1416,7 +1418,7 @@ static int wait_task_stopped(struct task_struct *p, if (unlikely(!task_is_stopped_or_traced(p))) goto unlock_sig; - if (!(p->ptrace & PT_PTRACED) && p->signal->group_stop_count > 0) + if (!ptrace && p->signal->group_stop_count > 0) /* * A group stop is in progress and this is the group leader. * We won't report until all threads have stopped. @@ -1445,7 +1447,7 @@ unlock_sig: */ get_task_struct(p); pid = task_pid_vnr(p); - why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED; + why = ptrace ? CLD_TRAPPED : CLD_STOPPED; read_unlock(&tasklist_lock); if (unlikely(options & WNOWAIT)) @@ -1536,7 +1538,7 @@ static int wait_task_continued(struct task_struct *p, int options, * Returns zero if the search for a child should continue; * then *@notask_error is 0 if @p is an eligible child, or still -ECHILD. */ -static int wait_consider_task(struct task_struct *parent, +static int wait_consider_task(struct task_struct *parent, int ptrace, struct task_struct *p, int *notask_error, enum pid_type type, struct pid *pid, int options, struct siginfo __user *infop, @@ -1546,6 +1548,15 @@ static int wait_consider_task(struct task_struct *parent, if (ret <= 0) return ret; + if (likely(!ptrace) && unlikely(p->ptrace)) { + /* + * This child is hidden by ptrace. + * We aren't allowed to see it now, but eventually we will. + */ + *notask_error = 0; + return 0; + } + if (p->exit_state == EXIT_DEAD) return 0; @@ -1562,7 +1573,8 @@ static int wait_consider_task(struct task_struct *parent, *notask_error = 0; if (task_is_stopped_or_traced(p)) - return wait_task_stopped(p, options, infop, stat_addr, ru); + return wait_task_stopped(ptrace, p, options, + infop, stat_addr, ru); return wait_task_continued(p, options, infop, stat_addr, ru); } @@ -1583,11 +1595,16 @@ static int do_wait_thread(struct task_struct *tsk, int *notask_error, struct task_struct *p; list_for_each_entry(p, &tsk->children, sibling) { - int ret = wait_consider_task(tsk, p, notask_error, - type, pid, options, - infop, stat_addr, ru); - if (ret) - return ret; + /* + * Do not consider detached threads. + */ + if (!task_detached(p)) { + int ret = wait_consider_task(tsk, 0, p, notask_error, + type, pid, options, + infop, stat_addr, ru); + if (ret) + return ret; + } } return 0; @@ -1601,21 +1618,16 @@ static int ptrace_do_wait(struct task_struct *tsk, int *notask_error, struct task_struct *p; /* - * If we never saw an eligile child, check for children stolen by - * ptrace. We don't leave -ECHILD in *@notask_error if there are any, - * because we will eventually be allowed to wait for them again. + * Traditionally we see ptrace'd stopped tasks regardless of options. */ - if (!*notask_error) - return 0; + options |= WUNTRACED; - list_for_each_entry(p, &tsk->ptrace_children, ptrace_list) { - int ret = eligible_child(type, pid, options, p); - if (unlikely(ret < 0)) + list_for_each_entry(p, &tsk->ptraced, ptrace_entry) { + int ret = wait_consider_task(tsk, 1, p, notask_error, + type, pid, options, + infop, stat_addr, ru); + if (ret) return ret; - if (ret) { - *notask_error = 0; - return 0; - } } return 0; diff --git a/kernel/fork.c b/kernel/fork.c index 4bd2f516401..adefc1131f2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1125,8 +1125,8 @@ static struct task_struct *copy_process(unsigned long clone_flags, */ p->group_leader = p; INIT_LIST_HEAD(&p->thread_group); - INIT_LIST_HEAD(&p->ptrace_children); - INIT_LIST_HEAD(&p->ptrace_list); + INIT_LIST_HEAD(&p->ptrace_entry); + INIT_LIST_HEAD(&p->ptraced); /* Now that the task is set up, run cgroup callbacks if * necessary. We need to run them before the task is visible @@ -1198,7 +1198,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, } if (likely(p->pid)) { - add_parent(p); + list_add_tail(&p->sibling, &p->real_parent->children); if (unlikely(p->ptrace & PT_PTRACED)) __ptrace_link(p, current->parent); diff --git a/kernel/ptrace.c b/kernel/ptrace.c index e337390fce0..8392a9da645 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -33,13 +33,9 @@ */ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) { - BUG_ON(!list_empty(&child->ptrace_list)); - if (child->parent == new_parent) - return; - list_add(&child->ptrace_list, &child->parent->ptrace_children); - remove_parent(child); + BUG_ON(!list_empty(&child->ptrace_entry)); + list_add(&child->ptrace_entry, &new_parent->ptraced); child->parent = new_parent; - add_parent(child); } /* @@ -73,12 +69,8 @@ void __ptrace_unlink(struct task_struct *child) BUG_ON(!child->ptrace); child->ptrace = 0; - if (ptrace_reparented(child)) { - list_del_init(&child->ptrace_list); - remove_parent(child); - child->parent = child->real_parent; - add_parent(child); - } + child->parent = child->real_parent; + list_del_init(&child->ptrace_entry); if (task_is_traced(child)) ptrace_untrace(child); @@ -492,15 +484,34 @@ int ptrace_traceme(void) /* * Are we already being traced? */ +repeat: task_lock(current); if (!(current->ptrace & PT_PTRACED)) { + /* + * See ptrace_attach() comments about the locking here. + */ + unsigned long flags; + if (!write_trylock_irqsave(&tasklist_lock, flags)) { + task_unlock(current); + do { + cpu_relax(); + } while (!write_can_lock(&tasklist_lock)); + goto repeat; + } + ret = security_ptrace(current->parent, current, PTRACE_MODE_ATTACH); + /* * Set the ptrace bit in the process ptrace flags. + * Then link us on our parent's ptraced list. */ - if (!ret) + if (!ret) { current->ptrace |= PT_PTRACED; + __ptrace_link(current, current->real_parent); + } + + write_unlock_irqrestore(&tasklist_lock, flags); } task_unlock(current); return ret; -- cgit v1.2.3-70-g09d2