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Message-ID: <20090330213747.606.81857.stgit@Aeon>
Date: Mon, 30 Mar 2009 14:37:47 -0700
From: Darren Hart <dvhltc@...ibm.com>
To: linux-kernel@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
Sripathi Kodi <sripathik@...ibm.com>,
Peter Zijlstra <peterz@...radead.org>,
John Stultz <johnstul@...ibm.com>,
Steven Rostedt <rostedt@...dmis.org>,
Dinakar Guniguntala <dino@...ibm.com>,
Ulrich Drepper <drepper@...hat.com>,
Eric Dumazet <dada1@...mosbay.com>,
Ingo Molnar <mingo@...e.hu>, Jakub Jelinek <jakub@...hat.com>,
Darren Hart <dvhltc@...ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
Sripathi Kodi <sripathik@...ibm.com>,
Peter Zijlstra <peterz@...radead.org>,
John Stultz <johnstul@...ibm.com>,
Steven Rostedt <rostedt@...dmis.org>,
Dinakar Guniguntala <dino@...ibm.com>,
Ulrich Drepper <drepper@...hat.com>,
Eric Dumazet <dada1@...mosbay.com>,
Ingo Molnar <mingo@...e.hu>, Jakub Jelinek <jakub@...hat.com>
Subject: [tip PATCH v6 2/8] RFC: futex: futex_top_waiter()
Improve legibility by wrapping finding the top waiter in a function. This
will be used by the follow-on patches for enabling requeue pi.
Changelog:
V6: -Shortened function length after review from tglx
-Corrected kernel-doc formatting
V4: -Simplified logic in the hb loop
-Return the futex_q as the task can be had from there if needed
-Updated comments and dropped the -safe iterator per review from tglx
V3: -Comment linewidth cleanup
V1: -Initial version
Signed-off-by: Darren Hart <dvhltc@...ibm.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Sripathi Kodi <sripathik@...ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: John Stultz <johnstul@...ibm.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Dinakar Guniguntala <dino@...ibm.com>
Cc: Ulrich Drepper <drepper@...hat.com>
Cc: Eric Dumazet <dada1@...mosbay.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Jakub Jelinek <jakub@...hat.com>
---
kernel/futex.c | 19 +++++++++++++++++++
1 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index b2ed762..8ebed88 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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