diff options
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 61 |
1 files changed, 23 insertions, 38 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index bc5395e66e97..c39d5f17946b 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1299,27 +1299,6 @@ static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key, return 0; } -static int lookup_pi_state(u32 __user *uaddr, u32 uval, - struct futex_hash_bucket *hb, - union futex_key *key, struct futex_pi_state **ps, - struct task_struct **exiting) -{ - struct futex_q *top_waiter = futex_top_waiter(hb, key); - - /* - * If there is a waiter on that futex, validate it and - * attach to the pi_state when the validation succeeds. - */ - if (top_waiter) - return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps); - - /* - * We are the first waiter - try to look up the owner based on - * @uval and attach to it. - */ - return attach_to_pi_owner(uaddr, uval, key, ps, exiting); -} - static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval) { int err; @@ -2038,8 +2017,8 @@ retry_private: * At this point the top_waiter has either taken uaddr2 or is * waiting on it. If the former, then the pi_state will not * exist yet, look it up one more time to ensure we have a - * reference to it. If the lock was taken, ret contains the - * vpid of the top waiter task. + * reference to it. If the lock was taken, @ret contains the + * VPID of the top waiter task. * If the lock was not taken, we have pi_state and an initial * refcount on it. In case of an error we have nothing. */ @@ -2047,19 +2026,25 @@ retry_private: WARN_ON(pi_state); task_count++; /* - * If we acquired the lock, then the user space value - * of uaddr2 should be vpid. It cannot be changed by - * the top waiter as it is blocked on hb2 lock if it - * tries to do so. If something fiddled with it behind - * our back the pi state lookup might unearth it. So - * we rather use the known value than rereading and - * handing potential crap to lookup_pi_state. + * If futex_proxy_trylock_atomic() acquired the + * user space futex, then the user space value + * @uaddr2 has been set to the @hb1's top waiter + * task VPID. This task is guaranteed to be alive + * and cannot be exiting because it is either + * sleeping or blocked on @hb2 lock. + * + * The @uaddr2 futex cannot have waiters either as + * otherwise futex_proxy_trylock_atomic() would not + * have succeeded. * - * If that call succeeds then we have pi_state and an - * initial refcount on it. + * In order to requeue waiters to @hb2, pi state is + * required. Hand in the VPID value (@ret) and + * allocate PI state with an initial refcount on + * it. */ - ret = lookup_pi_state(uaddr2, ret, hb2, &key2, - &pi_state, &exiting); + ret = attach_to_pi_owner(uaddr2, ret, &key2, &pi_state, + &exiting); + WARN_ON(ret); } switch (ret) { @@ -2183,9 +2168,9 @@ retry_private: } /* - * We took an extra initial reference to the pi_state either - * in futex_proxy_trylock_atomic() or in lookup_pi_state(). We - * need to drop it here again. + * We took an extra initial reference to the pi_state either in + * futex_proxy_trylock_atomic() or in attach_to_pi_owner(). We need + * to drop it here again. */ put_pi_state(pi_state); @@ -2364,7 +2349,7 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, * Modifying pi_state _before_ the user space value would leave the * pi_state in an inconsistent state when we fault here, because we * need to drop the locks to handle the fault. This might be observed - * in the PID check in lookup_pi_state. + * in the PID checks when attaching to PI state . */ retry: if (!argowner) { |