ANDROID: binder: add min sched_policy to node.
This change adds flags to flat_binder_object.flags
to allow indicating a minimum scheduling policy for
the node. It also clarifies the valid value range
for the priority bits in the flags.
Internally, we use the priority map that the kernel
uses, e.g. [0..99] for real-time policies and [100..139]
for the SCHED_NORMAL/SCHED_BATCH policies.
Bug: 34461621
Bug: 37293077
Change-Id: I12438deecb53df432da18c6fc77460768ae726d2
Signed-off-by: Martijn Coenen <maco@google.com>
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 94fb1e6..c99b4497 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -352,6 +352,8 @@
* and by @lock)
* @has_async_transaction: async transaction to node in progress
* (protected by @lock)
+ * @sched_policy: minimum scheduling policy for node
+ * (invariant after initialized)
* @accept_fds: file descriptor operations supported for node
* (invariant after initialized)
* @min_priority: minimum scheduling priority
@@ -391,6 +393,7 @@
/*
* invariant after initialization
*/
+ u8 sched_policy:2;
u8 accept_fds:1;
u8 min_priority;
};
@@ -1207,6 +1210,7 @@
binder_uintptr_t ptr = fp ? fp->binder : 0;
binder_uintptr_t cookie = fp ? fp->cookie : 0;
__u32 flags = fp ? fp->flags : 0;
+ s8 priority;
BUG_ON(!spin_is_locked(&proc->inner_lock));
while (*p) {
@@ -1238,8 +1242,10 @@
node->ptr = ptr;
node->cookie = cookie;
node->work.type = BINDER_WORK_NODE;
- node->min_priority = NICE_TO_PRIO(
- flags & FLAT_BINDER_FLAG_PRIORITY_MASK);
+ priority = flags & FLAT_BINDER_FLAG_PRIORITY_MASK;
+ node->sched_policy = (flags & FLAT_BINDER_FLAG_PRIORITY_MASK) >>
+ 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);
spin_lock_init(&node->lock);
INIT_LIST_HEAD(&node->work.entry);
@@ -4051,8 +4057,17 @@
tr.cookie = target_node->cookie;
t->saved_priority.sched_policy = current->policy;
t->saved_priority.prio = current->normal_prio;
- if (target_node->min_priority < t->priority.prio) {
- prio.sched_policy = SCHED_NORMAL;
+ if (target_node->min_priority < t->priority.prio ||
+ (target_node->min_priority == t->priority.prio &&
+ target_node->sched_policy == SCHED_FIFO)) {
+ /*
+ * In case the minimum priority on the node is
+ * higher (lower value), use that priority. If
+ * the priority is the same, but the node uses
+ * SCHED_FIFO, prefer SCHED_FIFO, since it can
+ * run unbounded, unlike SCHED_RR.
+ */
+ prio.sched_policy = target_node->sched_policy;
prio.prio = target_node->min_priority;
}
binder_set_priority(current, prio);
@@ -5091,8 +5106,9 @@
hlist_for_each_entry(ref, &node->refs, node_entry)
count++;
- seq_printf(m, " node %d: u%016llx c%016llx hs %d hw %d ls %d lw %d is %d iw %d tr %d",
+ seq_printf(m, " node %d: u%016llx c%016llx pri %d:%d hs %d hw %d ls %d lw %d is %d iw %d tr %d",
node->debug_id, (u64)node->ptr, (u64)node->cookie,
+ node->sched_policy, node->min_priority,
node->has_strong_ref, node->has_weak_ref,
node->local_strong_refs, node->local_weak_refs,
node->internal_strong_refs, count, node->tmp_refs);
diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h
index 7668b57..026558a 100644
--- a/include/uapi/linux/android/binder.h
+++ b/include/uapi/linux/android/binder.h
@@ -37,9 +37,48 @@
BINDER_TYPE_PTR = B_PACK_CHARS('p', 't', '*', B_TYPE_LARGE),
};
-enum {
+/**
+ * enum flat_binder_object_shifts: shift values for flat_binder_object_flags
+ * @FLAT_BINDER_FLAG_SCHED_POLICY_SHIFT: shift for getting scheduler policy.
+ *
+ */
+enum flat_binder_object_shifts {
+ FLAT_BINDER_FLAG_SCHED_POLICY_SHIFT = 9,
+};
+
+/**
+ * enum flat_binder_object_flags - flags for use in flat_binder_object.flags
+ */
+enum flat_binder_object_flags {
+ /**
+ * @FLAT_BINDER_FLAG_PRIORITY_MASK: bit-mask for min scheduler priority
+ *
+ * These bits can be used to set the minimum scheduler priority
+ * at which transactions into this node should run. Valid values
+ * in these bits depend on the scheduler policy encoded in
+ * @FLAT_BINDER_FLAG_SCHED_POLICY_MASK.
+ *
+ * For SCHED_NORMAL/SCHED_BATCH, the valid range is between [-20..19]
+ * For SCHED_FIFO/SCHED_RR, the value can run between [1..99]
+ */
FLAT_BINDER_FLAG_PRIORITY_MASK = 0xff,
+ /**
+ * @FLAT_BINDER_FLAG_ACCEPTS_FDS: whether the node accepts fds.
+ */
FLAT_BINDER_FLAG_ACCEPTS_FDS = 0x100,
+ /**
+ * @FLAT_BINDER_FLAG_SCHED_POLICY_MASK: bit-mask for scheduling policy
+ *
+ * These two bits can be used to set the min scheduling policy at which
+ * transactions on this node should run. These match the UAPI
+ * scheduler policy values, eg:
+ * 00b: SCHED_NORMAL
+ * 01b: SCHED_FIFO
+ * 10b: SCHED_RR
+ * 11b: SCHED_BATCH
+ */
+ FLAT_BINDER_FLAG_SCHED_POLICY_MASK =
+ 3U << FLAT_BINDER_FLAG_SCHED_POLICY_SHIFT,
};
#ifdef BINDER_IPC_32BIT