From 21dfe3ebac46ec1620de714804a0f67e9b050508 Mon Sep 17 00:00:00 2001 From: Martijn Coenen Date: Fri, 23 Jun 2017 10:13:43 -0700 Subject: [PATCH] ANDROID: binder: add RT inheritance flag to node. Allows a binder node to specify whether it wants to inherit real-time scheduling policy from a caller. Change-Id: I375b6094bf441c19f19cba06d5a6be02cd07d714 Signed-off-by: Martijn Coenen --- drivers/android/binder.c | 22 +++++++++++++++++----- include/uapi/linux/android/binder.h | 8 ++++++++ 2 files changed, 25 insertions(+), 5 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index fbebb319c48..efc68d91524 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -366,6 +366,8 @@ struct binder_error { * (invariant after initialized) * @min_priority: minimum scheduling priority * (invariant after initialized) + * @inherit_rt: inherit RT scheduling policy from caller + * (invariant after initialized) * @async_todo: list of async work items * (protected by @proc->inner_lock) * @@ -402,6 +404,7 @@ struct binder_node { * invariant after initialization */ u8 sched_policy:2; + u8 inherit_rt:1; u8 accept_fds:1; u8 min_priority; }; @@ -1173,7 +1176,8 @@ static void binder_set_priority(struct task_struct *task, static void binder_transaction_priority(struct task_struct *task, struct binder_transaction *t, - struct binder_priority node_prio) + struct binder_priority node_prio, + bool inherit_rt) { struct binder_priority desired_prio; @@ -1184,8 +1188,13 @@ static void binder_transaction_priority(struct task_struct *task, t->saved_priority.sched_policy = task->policy; t->saved_priority.prio = task->normal_prio; - desired_prio.prio = t->priority.prio; - desired_prio.sched_policy = t->priority.sched_policy; + if (!inherit_rt && is_rt_policy(desired_prio.sched_policy)) { + desired_prio.prio = NICE_TO_PRIO(0); + desired_prio.sched_policy = SCHED_NORMAL; + } else { + desired_prio.prio = t->priority.prio; + desired_prio.sched_policy = t->priority.sched_policy; + } if (node_prio.prio < t->priority.prio || (node_prio.prio == t->priority.prio && @@ -1290,6 +1299,7 @@ static struct binder_node *binder_init_node_ilocked( FLAT_BINDER_FLAG_SCHED_POLICY_SHIFT; node->min_priority = to_kernel_prio(node->sched_policy, priority); node->accept_fds = !!(flags & FLAT_BINDER_FLAG_ACCEPTS_FDS); + node->inherit_rt = !!(flags & FLAT_BINDER_FLAG_INHERIT_RT); spin_lock_init(&node->lock); INIT_LIST_HEAD(&node->work.entry); INIT_LIST_HEAD(&node->async_todo); @@ -2709,7 +2719,8 @@ static bool binder_proc_transaction(struct binder_transaction *t, if (thread) { target_list = &thread->todo; - binder_transaction_priority(thread->task, t, node_prio); + binder_transaction_priority(thread->task, t, node_prio, + node->inherit_rt); } else if (!target_list) { target_list = &proc->todo; } else { @@ -4107,7 +4118,8 @@ retry: tr.cookie = target_node->cookie; node_prio.sched_policy = target_node->sched_policy; node_prio.prio = target_node->min_priority; - binder_transaction_priority(current, t, node_prio); + binder_transaction_priority(current, t, node_prio, + target_node->inherit_rt); cmd = BR_TRANSACTION; } else { tr.target.ptr = 0; diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h index b1259d995de..1466631dba9 100644 --- a/include/uapi/linux/android/binder.h +++ b/include/uapi/linux/android/binder.h @@ -78,6 +78,14 @@ enum flat_binder_object_flags { */ FLAT_BINDER_FLAG_SCHED_POLICY_MASK = 3U << FLAT_BINDER_FLAG_SCHED_POLICY_SHIFT, + + /** + * @FLAT_BINDER_FLAG_INHERIT_RT: whether the node inherits RT policy + * + * Only when set, calls into this node will inherit a real-time + * scheduling policy from the caller (for synchronous transactions). + */ + FLAT_BINDER_FLAG_INHERIT_RT = 0x800, }; #ifdef BINDER_IPC_32BIT -- 2.20.1