From: tip-bot for Thomas Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org,
peterz@infradead.org, darren@dvhart.com, kees@outflux.net,
tglx@linutronix.de, davidlohr@hp.com
Subject: [tip:locking/core] futex: Use futex_top_waiter() in lookup_pi_state()
Date: Sat, 21 Jun 2014 13:33:31 -0700 [thread overview]
Message-ID: <tip-bd1dbcc67cd2c1181e2c01daac51eabf1b964dd8@git.kernel.org> (raw)
In-Reply-To: <20140611204237.092947239@linutronix.de>
Commit-ID: bd1dbcc67cd2c1181e2c01daac51eabf1b964dd8
Gitweb: http://git.kernel.org/tip/bd1dbcc67cd2c1181e2c01daac51eabf1b964dd8
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Wed, 11 Jun 2014 20:45:39 +0000
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 21 Jun 2014 22:26:23 +0200
futex: Use futex_top_waiter() in lookup_pi_state()
No point in open coding the same function again.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Kees Cook <kees@outflux.net>
Cc: wad@chromium.org
Link: http://lkml.kernel.org/r/20140611204237.092947239@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/futex.c | 124 ++++++++++++++++++++++++++++-----------------------------
1 file changed, 61 insertions(+), 63 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index 346d5c2..fff1ed9 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -796,87 +796,85 @@ static int
lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
union futex_key *key, struct futex_pi_state **ps)
{
+ struct futex_q *match = futex_top_waiter(hb, key);
struct futex_pi_state *pi_state = NULL;
- struct futex_q *this, *next;
struct task_struct *p;
pid_t pid = uval & FUTEX_TID_MASK;
- plist_for_each_entry_safe(this, next, &hb->chain, list) {
- if (match_futex(&this->key, key)) {
- /*
- * Sanity check the waiter before increasing
- * the refcount and attaching to it.
- */
- pi_state = this->pi_state;
- /*
- * Userspace might have messed up non-PI and
- * PI futexes [3]
- */
- if (unlikely(!pi_state))
- return -EINVAL;
+ if (match) {
+ /*
+ * Sanity check the waiter before increasing the
+ * refcount and attaching to it.
+ */
+ pi_state = match->pi_state;
+ /*
+ * Userspace might have messed up non-PI and PI
+ * futexes [3]
+ */
+ if (unlikely(!pi_state))
+ return -EINVAL;
- WARN_ON(!atomic_read(&pi_state->refcount));
+ WARN_ON(!atomic_read(&pi_state->refcount));
+ /*
+ * Handle the owner died case:
+ */
+ if (uval & FUTEX_OWNER_DIED) {
/*
- * Handle the owner died case:
+ * exit_pi_state_list sets owner to NULL and
+ * wakes the topmost waiter. The task which
+ * acquires the pi_state->rt_mutex will fixup
+ * owner.
*/
- if (uval & FUTEX_OWNER_DIED) {
+ if (!pi_state->owner) {
/*
- * exit_pi_state_list sets owner to NULL and
- * wakes the topmost waiter. The task which
- * acquires the pi_state->rt_mutex will fixup
- * owner.
+ * No pi state owner, but the user
+ * space TID is not 0. Inconsistent
+ * state. [5]
*/
- if (!pi_state->owner) {
- /*
- * No pi state owner, but the user
- * space TID is not 0. Inconsistent
- * state. [5]
- */
- if (pid)
- return -EINVAL;
- /*
- * Take a ref on the state and
- * return. [4]
- */
- goto out_state;
- }
-
- /*
- * If TID is 0, then either the dying owner
- * has not yet executed exit_pi_state_list()
- * or some waiter acquired the rtmutex in the
- * pi state, but did not yet fixup the TID in
- * user space.
- *
- * Take a ref on the state and return. [6]
- */
- if (!pid)
- goto out_state;
- } else {
+ if (pid)
+ return -EINVAL;
/*
- * If the owner died bit is not set,
- * then the pi_state must have an
- * owner. [7]
+ * Take a ref on the state and
+ * return. [4]
*/
- if (!pi_state->owner)
- return -EINVAL;
+ goto out_state;
}
/*
- * Bail out if user space manipulated the
- * futex value. If pi state exists then the
- * owner TID must be the same as the user
- * space TID. [9/10]
+ * If TID is 0, then either the dying owner
+ * has not yet executed exit_pi_state_list()
+ * or some waiter acquired the rtmutex in the
+ * pi state, but did not yet fixup the TID in
+ * user space.
+ *
+ * Take a ref on the state and return. [6]
+ */
+ if (!pid)
+ goto out_state;
+ } else {
+ /*
+ * If the owner died bit is not set,
+ * then the pi_state must have an
+ * owner. [7]
*/
- if (pid != task_pid_vnr(pi_state->owner))
+ if (!pi_state->owner)
return -EINVAL;
-
- out_state:
- atomic_inc(&pi_state->refcount);
- *ps = pi_state;
- return 0;
}
+
+ /*
+ * Bail out if user space manipulated the
+ * futex value. If pi state exists then the
+ * owner TID must be the same as the user
+ * space TID. [9/10]
+ */
+ if (pid != task_pid_vnr(pi_state->owner))
+ return -EINVAL;
+
+ out_state:
+ atomic_inc(&pi_state->refcount);
+ *ps = pi_state;
+ return 0;
}
/*
next prev parent reply other threads:[~2014-06-21 20:34 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-11 20:45 [patch 0/5] futex: More robustness tweaks Thomas Gleixner
2014-06-11 20:45 ` [patch 1/5] futex: Make unlock_pi more robust Thomas Gleixner
2014-06-16 16:18 ` Darren Hart
2014-06-16 22:15 ` Thomas Gleixner
2014-06-16 22:28 ` Thomas Gleixner
2014-06-16 22:49 ` Darren Hart
2014-06-16 22:39 ` Darren Hart
2014-06-21 20:33 ` [tip:locking/core] " tip-bot for Thomas Gleixner
2014-06-11 20:45 ` [patch 3/5] futex: Split out the waiter check from lookup_pi_state() Thomas Gleixner
2014-06-16 18:12 ` Darren Hart
2014-06-21 20:33 ` [tip:locking/core] " tip-bot for Thomas Gleixner
2014-06-11 20:45 ` [patch 2/5] futex: Use futex_top_waiter() in lookup_pi_state() Thomas Gleixner
2014-06-16 16:51 ` Darren Hart
2014-06-21 20:33 ` tip-bot for Thomas Gleixner [this message]
2014-06-11 20:45 ` [patch 4/5] futex: Split out the first waiter attachment from lookup_pi_state() Thomas Gleixner
2014-06-16 18:19 ` Darren Hart
2014-06-21 20:33 ` [tip:locking/core] " tip-bot for Thomas Gleixner
2014-06-11 20:45 ` [patch 5/5] futex: Simplify futex_lock_pi_atomic() and make it more robust Thomas Gleixner
2014-06-13 5:46 ` Darren Hart
2014-06-13 8:34 ` Thomas Gleixner
2014-06-13 9:36 ` Thomas Gleixner
2014-06-13 9:44 ` [patch V2 " Thomas Gleixner
2014-06-13 20:51 ` Davidlohr Bueso
2014-06-16 20:36 ` Darren Hart
2014-06-17 7:20 ` Thomas Gleixner
2014-06-21 20:34 ` [tip:locking/core] " tip-bot for Thomas Gleixner
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