Commit-ID: 4b1c486b3587d2abf50bee4a05eb488cd4045f2c
Gitweb: http://git.kernel.org/tip/4b1c486b3587d2abf50bee4a05eb488cd4045f2c
Author: Darren Hart <dvhltc@xxxxxxxxxx>
AuthorDate: Fri, 3 Apr 2009 13:39:42 -0700
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 6 Apr 2009 11:14:01 +0200
futex: add helper to find the top prio waiter of a futex
Improve legibility by wrapping finding the top waiter in a function.
This will be used by the follow-on patches for enabling requeue pi.
Signed-off-by: Darren Hart <dvhltc@xxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/futex.c | 19 +++++++++++++++++++
1 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index ebb48d6..421fb5e 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -276,6 +276,25 @@ void put_futex_key(int fshared, union futex_key *key)
drop_futex_key_refs(key);
}
+/**
+ * futex_top_waiter() - Return the highest priority waiter on a futex
+ * @hb: the hash bucket the futex_q's reside in
+ * @key: the futex key (to distinguish it from other futex futex_q's)
+ *
+ * Must be called with the hb lock held.
+ */
+static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb,
+ union futex_key *key)
+{
+ struct futex_q *this;
+
+ plist_for_each_entry(this, &hb->chain, list) {
+ if (match_futex(&this->key, key))
+ return this;
+ }
+ return NULL;
+}
+
static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval)
{
u32 curval;
--
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