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android: binder: have threads inherit scheduling policy.

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If the source thread of a transaction runs with a real-time
policy such as SCHED_FIFO or SCHED_RR, have the thread handling
the transaction run with the same policy.

Change-Id: I5badf2bdc1702c83e20264b5c40e53a62d22ba61
Signed-off-by: Martijn Coenen <maco@android.com>
This commit is contained in:
Martijn Coenen
2017-02-02 14:59:42 +01:00
committed by Thierry Strudel
parent e04d752ca7
commit 7a154d0e3e
1 changed files with 64 additions and 8 deletions
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72
drivers/android/binder.c
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@@ -530,6 +530,9 @@ struct binder_transaction {
unsigned int flags;
long priority;
long saved_priority;
int sched_policy;
int saved_sched_policy;
int rt_priority;
kuid_t sender_euid;
};
@@ -607,6 +610,63 @@ static void binder_set_nice(long nice)
binder_user_error("%d RLIMIT_NICE not set\n", current->pid);
}
static inline int is_rt_policy(int sched_policy)
{
return (sched_policy == SCHED_FIFO || sched_policy == SCHED_RR);
}
static void binder_set_priority(
struct binder_transaction *t, struct binder_node *target_node)
{
bool oneway = !!(t->flags & TF_ONE_WAY);
t->saved_sched_policy = current->policy;
t->saved_priority = task_nice(current);
if (is_rt_policy(t->sched_policy) && !is_rt_policy(current->policy)) {
/* Transaction was initiated with a real-time policy,
* but we are not; temporarily upgrade this thread to RT.
*/
struct sched_param params = {t->rt_priority};
sched_setscheduler_nocheck(current,
t->sched_policy |
SCHED_RESET_ON_FORK,
&params);
} else if (!is_rt_policy(current->policy)) {
/* Neither policy is real-time, fall back to setting nice. */
if (t->priority < target_node->min_priority && !oneway)
binder_set_nice(t->priority);
else if (!oneway ||
t->saved_priority > target_node->min_priority)
binder_set_nice(target_node->min_priority);
} else {
/* Cases where we do nothing:
* 1. Both source and target threads have a real-time policy
* 2. Source does not have a real-time policy, but the target
* does.
*/
}
}
static void binder_restore_priority(struct binder_transaction *t)
{
struct sched_param params = {0};
if (current->policy != t->saved_sched_policy) {
/* Binder only transitions from a non-RT to a RT
* policy; therefore, the restore should always
* be a non-RT policy, and params.priority is not
* relevant.
*/
sched_setscheduler_nocheck(current,
t->saved_sched_policy,
&params);
}
if (!is_rt_policy(t->saved_sched_policy))
binder_set_nice(t->saved_priority);
}
static struct binder_node *binder_get_node(struct binder_proc *proc,
binder_uintptr_t ptr)
{
@@ -1788,7 +1848,7 @@ static void binder_transaction(struct binder_proc *proc,
}
thread->transaction_stack = in_reply_to->to_parent;
binder_proc_unlock(thread->proc, __LINE__);
binder_set_nice(in_reply_to->saved_priority);
binder_restore_priority(in_reply_to);
target_thread = in_reply_to->from;
if (target_thread == NULL) {
return_error = BR_DEAD_REPLY;
@@ -1916,7 +1976,9 @@ static void binder_transaction(struct binder_proc *proc,
t->to_thread = target_thread;
t->code = tr->code;
t->flags = tr->flags;
t->sched_policy = current->policy;
t->priority = task_nice(current);
t->rt_priority = current->rt_priority;
trace_binder_transaction(reply, t, target_node);
@@ -2982,13 +3044,7 @@ retry:
tr.target.ptr = target_node->ptr;
tr.cookie = target_node->cookie;
t->saved_priority = task_nice(current);
if (t->priority < target_node->min_priority &&
!(t->flags & TF_ONE_WAY))
binder_set_nice(t->priority);
else if (!(t->flags & TF_ONE_WAY) ||
t->saved_priority > target_node->min_priority)
binder_set_nice(target_node->min_priority);
binder_set_priority(t, target_node);
cmd = BR_TRANSACTION;
} else {
tr.target.ptr = 0;