From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754363AbaFKUqo (ORCPT ); Wed, 11 Jun 2014 16:46:44 -0400 Received: from www.linutronix.de ([62.245.132.108]:34848 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752955AbaFKUpm (ORCPT ); Wed, 11 Jun 2014 16:45:42 -0400 Message-Id: <20140611204237.092947239@linutronix.de> User-Agent: quilt/0.63-1 Date: Wed, 11 Jun 2014 20:45:39 -0000 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Darren Hart , Ingo Molnar , Davidlohr Bueso , Kees Cook , wad@chromium.org Subject: [patch 2/5] futex: Use futex_top_waiter() in lookup_pi_state() References: <20140611202744.676528190@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=futex-use-futex-top-waiter-for-lookup.patch X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org No point in open coding the same function again. Signed-off-by: Thomas Gleixner --- kernel/futex.c | 128 ++++++++++++++++++++++++++++----------------------------- 1 file changed, 63 insertions(+), 65 deletions(-) Index: linux/kernel/futex.c =================================================================== --- linux.orig/kernel/futex.c +++ linux/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)) { + 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)); + + /* + * Handle the owner died case: + */ + if (uval & FUTEX_OWNER_DIED) { /* - * Sanity check the waiter before increasing - * the refcount and attaching to it. + * 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. */ - pi_state = this->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)); - - /* - * Handle the owner died case: - */ - if (uval & FUTEX_OWNER_DIED) { - /* - * 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 (!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 (!pi_state->owner) { /* - * 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] + * No pi state owner, but the user + * space TID is not 0. Inconsistent + * state. [5] */ - 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 != task_pid_vnr(pi_state->owner)) + if (!pid) + goto out_state; + } else { + /* + * If the owner died bit is not set, + * then the pi_state must have an + * owner. [7] + */ + 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; } /*