From 1227dd773d8d4e3983b4b751f9ffa0f41402fb7c Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 24 Apr 2012 02:44:49 -0400 Subject: TIF_NOTIFY_RESUME is defined on all targets now Signed-off-by: Al Viro --- include/linux/tracehook.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index 51bd91d911c3..8a2a3fc9bd05 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -153,7 +153,6 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, ptrace_notify(SIGTRAP); } -#ifdef TIF_NOTIFY_RESUME /** * set_notify_resume - cause tracehook_notify_resume() to be called * @task: task that will call tracehook_notify_resume() @@ -185,6 +184,5 @@ static inline void set_notify_resume(struct task_struct *task) static inline void tracehook_notify_resume(struct pt_regs *regs) { } -#endif /* TIF_NOTIFY_RESUME */ #endif /* */ -- cgit v1.2.3 From a42c6ded827dbd396d2efde7530620be029a72d1 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 23 May 2012 14:44:37 -0400 Subject: move key_repace_session_keyring() into tracehook_notify_resume() Signed-off-by: Al Viro --- include/linux/tracehook.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index 8a2a3fc9bd05..b9ca903bb553 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -183,6 +183,8 @@ static inline void set_notify_resume(struct task_struct *task) */ static inline void tracehook_notify_resume(struct pt_regs *regs) { + if (current->replacement_session_keyring) + key_replace_session_keyring(); } #endif /* */ -- cgit v1.2.3 From e73f8959af0439d114847eab5a8a5ce48f1217c4 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 11 May 2012 10:59:07 +1000 Subject: task_work_add: generic process-context callbacks Provide a simple mechanism that allows running code in the (nonatomic) context of the arbitrary task. The caller does task_work_add(task, task_work) and this task executes task_work->func() either from do_notify_resume() or from do_exit(). The callback can rely on PF_EXITING to detect the latter case. "struct task_work" can be embedded in another struct, still it has "void *data" to handle the most common/simple case. This allows us to kill the ->replacement_session_keyring hack, and potentially this can have more users. Performance-wise, this adds 2 "unlikely(!hlist_empty())" checks into tracehook_notify_resume() and do_exit(). But at the same time we can remove the "replacement_session_keyring != NULL" checks from arch/*/signal.c and exit_creds(). Note: task_work_add/task_work_run abuses ->pi_lock. This is only because this lock is already used by lookup_pi_state() to synchronize with do_exit() setting PF_EXITING. Fortunately the scope of this lock in task_work.c is really tiny, and the code is unlikely anyway. Signed-off-by: Oleg Nesterov Acked-by: David Howells Cc: Thomas Gleixner Cc: Richard Kuo Cc: Linus Torvalds Cc: Alexander Gordeev Cc: Chris Zankel Cc: David Smith Cc: "Frank Ch. Eigler" Cc: Geert Uytterhoeven Cc: Larry Woodman Cc: Peter Zijlstra Cc: Tejun Heo Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- include/linux/sched.h | 2 ++ include/linux/task_work.h | 33 +++++++++++++++++++++++++++++++++ include/linux/tracehook.h | 11 +++++++++++ 3 files changed, 46 insertions(+) create mode 100644 include/linux/task_work.h (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index 5ea8baea9387..7930131abc1a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1400,6 +1400,8 @@ struct task_struct { int (*notifier)(void *priv); void *notifier_data; sigset_t *notifier_mask; + struct hlist_head task_works; + struct audit_context *audit_context; #ifdef CONFIG_AUDITSYSCALL uid_t loginuid; diff --git a/include/linux/task_work.h b/include/linux/task_work.h new file mode 100644 index 000000000000..294d5d5e90b1 --- /dev/null +++ b/include/linux/task_work.h @@ -0,0 +1,33 @@ +#ifndef _LINUX_TASK_WORK_H +#define _LINUX_TASK_WORK_H + +#include +#include + +struct task_work; +typedef void (*task_work_func_t)(struct task_work *); + +struct task_work { + struct hlist_node hlist; + task_work_func_t func; + void *data; +}; + +static inline void +init_task_work(struct task_work *twork, task_work_func_t func, void *data) +{ + twork->func = func; + twork->data = data; +} + +int task_work_add(struct task_struct *task, struct task_work *twork, bool); +struct task_work *task_work_cancel(struct task_struct *, task_work_func_t); +void task_work_run(void); + +static inline void exit_task_work(struct task_struct *task) +{ + if (unlikely(!hlist_empty(&task->task_works))) + task_work_run(); +} + +#endif /* _LINUX_TASK_WORK_H */ diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index b9ca903bb553..b2dd0917ca0d 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -49,6 +49,7 @@ #include #include #include +#include struct linux_binprm; /* @@ -164,8 +165,10 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, */ static inline void set_notify_resume(struct task_struct *task) { +#ifdef TIF_NOTIFY_RESUME if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME)) kick_process(task); +#endif } /** @@ -185,6 +188,14 @@ static inline void tracehook_notify_resume(struct pt_regs *regs) { if (current->replacement_session_keyring) key_replace_session_keyring(); + /* + * The caller just cleared TIF_NOTIFY_RESUME. This barrier + * pairs with task_work_add()->set_notify_resume() after + * hlist_add_head(task->task_works); + */ + smp_mb__after_clear_bit(); + if (unlikely(!hlist_empty(¤t->task_works))) + task_work_run(); } #endif /* */ -- cgit v1.2.3 From 4d1d61a6b203d957777d73fcebf19d90b038b5b2 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 11 May 2012 10:59:08 +1000 Subject: genirq: reimplement exit_irq_thread() hook via task_work_add() exit_irq_thread() and task->irq_thread are needed to handle the unexpected (and unlikely) exit of irq-thread. We can use task_work instead and make this all private to kernel/irq/manage.c, cleanup plus micro-optimization. 1. rename exit_irq_thread() to irq_thread_dtor(), make it static, and move it up before irq_thread(). 2. change irq_thread() to do task_work_add(irq_thread_dtor) at the start and task_work_cancel() before return. tracehook_notify_resume() can never play with kthreads, only do_exit()->exit_task_work() can call the callback and this is what we want. 3. remove task_struct->irq_thread and the special hook in do_exit(). Signed-off-by: Oleg Nesterov Reviewed-by: Thomas Gleixner Cc: David Howells Cc: Richard Kuo Cc: Linus Torvalds Cc: Alexander Gordeev Cc: Chris Zankel Cc: David Smith Cc: "Frank Ch. Eigler" Cc: Geert Uytterhoeven Cc: Larry Woodman Cc: Peter Zijlstra Cc: Tejun Heo Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- include/linux/interrupt.h | 4 ---- include/linux/sched.h | 10 ++-------- 2 files changed, 2 insertions(+), 12 deletions(-) (limited to 'include/linux') diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index c91171599cb6..e68a8e53bb59 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -142,8 +142,6 @@ request_any_context_irq(unsigned int irq, irq_handler_t handler, extern int __must_check request_percpu_irq(unsigned int irq, irq_handler_t handler, const char *devname, void __percpu *percpu_dev_id); - -extern void exit_irq_thread(void); #else extern int __must_check @@ -177,8 +175,6 @@ request_percpu_irq(unsigned int irq, irq_handler_t handler, { return request_irq(irq, handler, 0, devname, percpu_dev_id); } - -static inline void exit_irq_thread(void) { } #endif extern void free_irq(unsigned int, void *); diff --git a/include/linux/sched.h b/include/linux/sched.h index 7930131abc1a..da013853a622 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1301,11 +1301,6 @@ struct task_struct { unsigned sched_reset_on_fork:1; unsigned sched_contributes_to_load:1; -#ifdef CONFIG_GENERIC_HARDIRQS - /* IRQ handler threads */ - unsigned irq_thread:1; -#endif - pid_t pid; pid_t tgid; @@ -1313,10 +1308,9 @@ struct task_struct { /* Canary value for the -fstack-protector gcc feature */ unsigned long stack_canary; #endif - - /* + /* * pointers to (original) parent process, youngest child, younger sibling, - * older sibling, respectively. (p->father can be replaced with + * older sibling, respectively. (p->father can be replaced with * p->real_parent->pid) */ struct task_struct __rcu *real_parent; /* real parent process */ -- cgit v1.2.3 From 413cd3d9abeaef590e5ce00564f7a443165db238 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 11 May 2012 10:59:08 +1000 Subject: keys: change keyctl_session_to_parent() to use task_work_add() Change keyctl_session_to_parent() to use task_work_add() and move key_replace_session_keyring() logic into task_work->func(). Note that we do task_work_cancel() before task_work_add() to ensure that only one work can be pending at any time. This is important, we must not allow user-space to abuse the parent's ->task_works list. The callback, replace_session_keyring(), checks PF_EXITING. I guess this is not really needed but looks better. As a side effect, this fixes the (unlikely) race. The callers of key_replace_session_keyring() and keyctl_session_to_parent() lack the necessary barriers, the parent can miss the request. Now we can remove task_struct->replacement_session_keyring and related code. Signed-off-by: Oleg Nesterov Acked-by: David Howells Cc: Thomas Gleixner Cc: Richard Kuo Cc: Linus Torvalds Cc: Alexander Gordeev Cc: Chris Zankel Cc: David Smith Cc: "Frank Ch. Eigler" Cc: Geert Uytterhoeven Cc: Larry Woodman Cc: Peter Zijlstra Cc: Tejun Heo Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- include/linux/key.h | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/key.h b/include/linux/key.h index 5231800770e1..2a0ee11584e9 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -33,6 +33,8 @@ typedef uint32_t key_perm_t; struct key; +#define key_replace_session_keyring() do { } while (0) + #ifdef CONFIG_KEYS #undef KEY_DEBUGGING @@ -308,9 +310,6 @@ static inline bool key_is_instantiated(const struct key *key) #ifdef CONFIG_SYSCTL extern ctl_table key_sysctls[]; #endif - -extern void key_replace_session_keyring(void); - /* * the userspace interface */ @@ -334,7 +333,6 @@ extern void key_init(void); #define key_fsuid_changed(t) do { } while(0) #define key_fsgid_changed(t) do { } while(0) #define key_init() do { } while(0) -#define key_replace_session_keyring() do { } while(0) #endif /* CONFIG_KEYS */ #endif /* __KERNEL__ */ -- cgit v1.2.3 From dea649b8ac1861107c5d91e1a71121434fc64193 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 11 May 2012 10:59:09 +1000 Subject: keys: kill the dummy key_replace_session_keyring() After the previouse change key_replace_session_keyring() becomes a nop. Remove the dummy definition in key.h and update the callers in arch/*/kernel/signal.c. Signed-off-by: Oleg Nesterov Acked-by: David Howells Cc: Thomas Gleixner Cc: Richard Kuo Cc: Linus Torvalds Cc: Alexander Gordeev Cc: Chris Zankel Cc: David Smith Cc: "Frank Ch. Eigler" Cc: Geert Uytterhoeven Cc: Larry Woodman Cc: Peter Zijlstra Cc: Tejun Heo Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- include/linux/key.h | 2 -- include/linux/tracehook.h | 2 -- 2 files changed, 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/key.h b/include/linux/key.h index 2a0ee11584e9..4cd22ed627ef 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -33,8 +33,6 @@ typedef uint32_t key_perm_t; struct key; -#define key_replace_session_keyring() do { } while (0) - #ifdef CONFIG_KEYS #undef KEY_DEBUGGING diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index b2dd0917ca0d..6a4d82bedb03 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -186,8 +186,6 @@ static inline void set_notify_resume(struct task_struct *task) */ static inline void tracehook_notify_resume(struct pt_regs *regs) { - if (current->replacement_session_keyring) - key_replace_session_keyring(); /* * The caller just cleared TIF_NOTIFY_RESUME. This barrier * pairs with task_work_add()->set_notify_resume() after -- cgit v1.2.3 From f23ca335462e3c84f13270b9e65f83936068ec2c Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 11 May 2012 10:59:09 +1000 Subject: keys: kill task_struct->replacement_session_keyring Kill the no longer used task_struct->replacement_session_keyring, update copy_creds() and exit_creds(). Signed-off-by: Oleg Nesterov Acked-by: David Howells Cc: Thomas Gleixner Cc: Richard Kuo Cc: Linus Torvalds Cc: Alexander Gordeev Cc: Chris Zankel Cc: David Smith Cc: "Frank Ch. Eigler" Cc: Geert Uytterhoeven Cc: Larry Woodman Cc: Peter Zijlstra Cc: Tejun Heo Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- include/linux/sched.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/sched.h b/include/linux/sched.h index da013853a622..17c6c929ee94 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1357,8 +1357,6 @@ struct task_struct { * credentials (COW) */ const struct cred __rcu *cred; /* effective (overridable) subjective task * credentials (COW) */ - struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */ - char comm[TASK_COMM_LEN]; /* executable name excluding path - access with [gs]et_task_comm (which lock it with task_lock()) -- cgit v1.2.3