The fake signal is send automatically now. We can rely on it completely and remove the sysfs attribute.
Signed-off-by: Miroslav Benes <[email protected]> --- .../ABI/testing/sysfs-kernel-livepatch | 12 --- Documentation/livepatch/livepatch.txt | 16 ++-- kernel/livepatch/core.c | 32 -------- kernel/livepatch/transition.c | 82 +++++++++---------- kernel/livepatch/transition.h | 1 - 5 files changed, 48 insertions(+), 95 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch index dac7e1e62a8b..85db352f68f9 100644 --- a/Documentation/ABI/testing/sysfs-kernel-livepatch +++ b/Documentation/ABI/testing/sysfs-kernel-livepatch @@ -33,18 +33,6 @@ Contact: [email protected] An attribute which indicates whether the patch is currently in transition. -What: /sys/kernel/livepatch/<patch>/signal -Date: Nov 2017 -KernelVersion: 4.15.0 -Contact: [email protected] -Description: - A writable attribute that allows administrator to affect the - course of an existing transition. Writing 1 sends a fake - signal to all remaining blocking tasks. The fake signal - means that no proper signal is delivered (there is no data in - signal pending structures). Tasks are interrupted or woken up, - and forced to change their patched state. - What: /sys/kernel/livepatch/<patch>/force Date: Nov 2017 KernelVersion: 4.15.0 diff --git a/Documentation/livepatch/livepatch.txt b/Documentation/livepatch/livepatch.txt index 407e0f03dc99..4627b41ff02e 100644 --- a/Documentation/livepatch/livepatch.txt +++ b/Documentation/livepatch/livepatch.txt @@ -158,13 +158,11 @@ If a patch is in transition, this file shows 0 to indicate the task is unpatched and 1 to indicate it's patched. Otherwise, if no patch is in transition, it shows -1. Any tasks which are blocking the transition can be signaled with SIGSTOP and SIGCONT to force them to change their -patched state. This may be harmful to the system though. -/sys/kernel/livepatch/<patch>/signal attribute provides a better alternative. -Writing 1 to the attribute sends a fake signal to all remaining blocking -tasks. No proper signal is actually delivered (there is no data in signal -pending structures). Tasks are interrupted or woken up, and forced to change -their patched state. Despite the sysfs attribute the fake signal is also sent -every 15 seconds automatically. +patched state. This may be harmful to the system though. Sending a fake signal +to all remaining blocking tasks is a better alternative. No proper signal is +actually delivered (there is no data in signal pending structures). Tasks are +interrupted or woken up, and forced to change their patched state. The fake +signal is automatically sent every 15 seconds. Administrator can also affect a transition through /sys/kernel/livepatch/<patch>/force attribute. Writing 1 there clears @@ -412,8 +410,8 @@ Information about the registered patches can be found under /sys/kernel/livepatch. The patches could be enabled and disabled by writing there. -/sys/kernel/livepatch/<patch>/signal and /sys/kernel/livepatch/<patch>/force -attributes allow administrator to affect a patching operation. +/sys/kernel/livepatch/<patch>/force attributes allow administrator to affect a +patching operation. See Documentation/ABI/testing/sysfs-kernel-livepatch for more details. diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index adca5cf07f7e..fe1993399823 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -313,7 +313,6 @@ static int klp_write_object_relocations(struct module *pmod, * /sys/kernel/livepatch/<patch> * /sys/kernel/livepatch/<patch>/enabled * /sys/kernel/livepatch/<patch>/transition - * /sys/kernel/livepatch/<patch>/signal * /sys/kernel/livepatch/<patch>/force * /sys/kernel/livepatch/<patch>/<object> * /sys/kernel/livepatch/<patch>/<object>/<function,sympos> @@ -382,35 +381,6 @@ static ssize_t transition_show(struct kobject *kobj, patch == klp_transition_patch); } -static ssize_t signal_store(struct kobject *kobj, struct kobj_attribute *attr, - const char *buf, size_t count) -{ - struct klp_patch *patch; - int ret; - bool val; - - ret = kstrtobool(buf, &val); - if (ret) - return ret; - - if (!val) - return count; - - mutex_lock(&klp_mutex); - - patch = container_of(kobj, struct klp_patch, kobj); - if (patch != klp_transition_patch) { - mutex_unlock(&klp_mutex); - return -EINVAL; - } - - klp_send_signals(); - - mutex_unlock(&klp_mutex); - - return count; -} - static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count) { @@ -442,12 +412,10 @@ static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled); static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition); -static struct kobj_attribute signal_kobj_attr = __ATTR_WO(signal); static struct kobj_attribute force_kobj_attr = __ATTR_WO(force); static struct attribute *klp_patch_attrs[] = { &enabled_kobj_attr.attr, &transition_kobj_attr.attr, - &signal_kobj_attr.attr, &force_kobj_attr.attr, NULL }; diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index 12a1a65531a0..79876744d8da 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -347,6 +347,47 @@ static bool klp_try_switch_task(struct task_struct *task) } +/* + * Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set. + * Kthreads with TIF_PATCH_PENDING set are woken up. + */ +static void klp_send_signals(void) +{ + struct task_struct *g, *task; + + if (klp_signals_cnt == SIGNALS_TIMEOUT) + pr_notice("signaling remaining tasks\n"); + + read_lock(&tasklist_lock); + for_each_process_thread(g, task) { + if (!klp_patch_pending(task)) + continue; + + /* + * There is a small race here. We could see TIF_PATCH_PENDING + * set and decide to wake up a kthread or send a fake signal. + * Meanwhile the task could migrate itself and the action + * would be meaningless. It is not serious though. + */ + if (task->flags & PF_KTHREAD) { + /* + * Wake up a kthread which sleeps interruptedly and + * still has not been migrated. + */ + wake_up_state(task, TASK_INTERRUPTIBLE); + } else { + /* + * Send fake signal to all non-kthread tasks which are + * still not migrated. + */ + spin_lock_irq(&task->sighand->siglock); + signal_wake_up(task, 0); + spin_unlock_irq(&task->sighand->siglock); + } + } + read_unlock(&tasklist_lock); +} + /* * Try to switch all remaining tasks to the target patch state by walking the * stacks of sleeping tasks and looking for any to-be-patched or @@ -587,47 +628,6 @@ void klp_copy_process(struct task_struct *child) /* TIF_PATCH_PENDING gets copied in setup_thread_stack() */ } -/* - * Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set. - * Kthreads with TIF_PATCH_PENDING set are woken up. - */ -void klp_send_signals(void) -{ - struct task_struct *g, *task; - - if (klp_signals_cnt == SIGNALS_TIMEOUT) - pr_notice("signaling remaining tasks\n"); - - read_lock(&tasklist_lock); - for_each_process_thread(g, task) { - if (!klp_patch_pending(task)) - continue; - - /* - * There is a small race here. We could see TIF_PATCH_PENDING - * set and decide to wake up a kthread or send a fake signal. - * Meanwhile the task could migrate itself and the action - * would be meaningless. It is not serious though. - */ - if (task->flags & PF_KTHREAD) { - /* - * Wake up a kthread which sleeps interruptedly and - * still has not been migrated. - */ - wake_up_state(task, TASK_INTERRUPTIBLE); - } else { - /* - * Send fake signal to all non-kthread tasks which are - * still not migrated. - */ - spin_lock_irq(&task->sighand->siglock); - signal_wake_up(task, 0); - spin_unlock_irq(&task->sighand->siglock); - } - } - read_unlock(&tasklist_lock); -} - /* * Drop TIF_PATCH_PENDING of all tasks on admin's request. This forces an * existing transition to finish. diff --git a/kernel/livepatch/transition.h b/kernel/livepatch/transition.h index f9d0bc016067..322db16233de 100644 --- a/kernel/livepatch/transition.h +++ b/kernel/livepatch/transition.h @@ -11,7 +11,6 @@ void klp_cancel_transition(void); void klp_start_transition(void); void klp_try_complete_transition(void); void klp_reverse_transition(void); -void klp_send_signals(void); void klp_force_transition(void); #endif /* _LIVEPATCH_TRANSITION_H */ -- 2.20.1
