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Subject[PATCH v3 05/13] futex: Add a new futex type field into futex_state
Date
As the futex_state structure will be overloaded in later patches
to be used by non-PI futexes, it is necessary to add a type field to
distinguish among different types of futexes.

Signed-off-by: Waiman Long <Waiman.Long@hpe.com>
---
kernel/futex.c | 14 ++++++++++----
1 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 0d1b1be..a496c01 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -191,6 +191,10 @@ int __read_mostly futex_cmpxchg_enabled;
#define FLAGS_CLOCKRT 0x02
#define FLAGS_HAS_TIMEOUT 0x04

+enum futex_type {
+ TYPE_PI = 0,
+};
+
/*
* Futex state object:
* - Priority Inheritance state
@@ -210,6 +214,7 @@ struct futex_state {
struct task_struct *owner;
atomic_t refcount;

+ enum futex_type type;
union futex_key key;
};

@@ -897,10 +902,10 @@ static void put_futex_state(struct futex_state *state)
return;

/*
- * If state->owner is NULL, the owner is most probably dying
- * and has cleaned up the futex state already
+ * If state->owner is NULL and the type is TYPE_PI, the owner is
+ * most probably dying and has cleaned up the futex state already
*/
- if (state->owner) {
+ if (state->owner && (state->type == TYPE_PI)) {
task_pi_list_del(state->owner, state, false);

rt_mutex_proxy_unlock(&state->pi_mutex, state->owner);
@@ -1056,7 +1061,7 @@ static int attach_to_pi_state(u32 uval, struct futex_state *pi_state,
/*
* Userspace might have messed up non-PI and PI futexes [3]
*/
- if (unlikely(!pi_state))
+ if (unlikely(!pi_state || (pi_state->type != TYPE_PI)))
return -EINVAL;

WARN_ON(!atomic_read(&pi_state->refcount));
@@ -1174,6 +1179,7 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key,

/* Store the key for possible exit cleanups: */
pi_state->key = *key;
+ pi_state->type = TYPE_PI;

WARN_ON(!list_empty(&pi_state->list));
list_add(&pi_state->list, &p->pi_state_list);
--
1.7.1
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