On Thu, Feb 13, 2020 at 06:45:22PM -0300, André Almeida wrote:
@@ -150,4 +153,21 @@ struct robust_list_head { (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) +/*
- Maximum number of multiple futexes to wait for
- */
+#define FUTEX_MULTIPLE_MAX_COUNT 128
+/**
- struct futex_wait_block - Block of futexes to be waited for
- @uaddr: User address of the futex
- @val: Futex value expected by userspace
- @bitset: Bitset for the optional bitmasked wakeup
- */
+struct futex_wait_block {
- __u32 __user *uaddr;
- __u32 val;
- __u32 bitset;
+};
So I have a problem with this vector layout, it doesn't allow for per-futex flags, and esp. with that multi-size futex support that becomes important, but also with the already extand private/shared and wait_bitset flags this means you cannot have a vector with mixed wait types.
#endif /* _UAPI_LINUX_FUTEX_H */ diff --git a/kernel/futex.c b/kernel/futex.c index 0cf84c8664f2..58cf9eb2b851 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -215,6 +215,8 @@ struct futex_pi_state {
- @rt_waiter: rt_waiter storage for use with requeue_pi
- @requeue_pi_key: the requeue_pi target futex key
- @bitset: bitset for the optional bitmasked wakeup
- @uaddr: userspace address of futex
- @uval: expected futex's value
- We use this hashed waitqueue, instead of a normal wait_queue_entry_t, so
- we can wake only the relevant ones (hashed queues may be shared).
@@ -237,6 +239,8 @@ struct futex_q { struct rt_mutex_waiter *rt_waiter; union futex_key *requeue_pi_key; u32 bitset;
- u32 __user *uaddr;
- u32 uval;
} __randomize_layout;
That creates a hole for no reason.