From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932955AbXBLDns (ORCPT ); Sun, 11 Feb 2007 22:43:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932956AbXBLDnr (ORCPT ); Sun, 11 Feb 2007 22:43:47 -0500 Received: from ozlabs.org ([203.10.76.45]:50969 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932955AbXBLDnq (ORCPT ); Sun, 11 Feb 2007 22:43:46 -0500 Subject: [PATCH 2/2] lguest preparation: expose futex infrastructure: get_futex_key, get_key_refs and drop_key_refs From: Rusty Russell To: Andrew Morton Cc: lkml - Kernel Mailing List , virtualization , Ingo Molnar In-Reply-To: <1171251698.10409.20.camel@localhost.localdomain> References: <1171251120.10409.2.camel@localhost.localdomain> <1171251185.10409.4.camel@localhost.localdomain> <1171251258.10409.7.camel@localhost.localdomain> <1171251335.10409.10.camel@localhost.localdomain> <1171251406.10409.13.camel@localhost.localdomain> <1171251471.10409.15.camel@localhost.localdomain> <1171251578.10409.17.camel@localhost.localdomain> <1171251698.10409.20.camel@localhost.localdomain> Content-Type: text/plain Date: Mon, 12 Feb 2007 14:42:50 +1100 Message-Id: <1171251770.10409.23.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org lguest uses the convenient futex infrastructure for inter-domain I/O, so expose get_futex_key, get_key_refs (renamed get_futex_key_refs) and drop_key_refs (renamed drop_futex_key_refs). Also means we need to expose the union that these use. No code changes. Signed-off-by: Rusty Russell =================================================================== --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -100,6 +100,35 @@ extern int extern int handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi); +/* + * Futexes are matched on equal values of this key. + * The key type depends on whether it's a shared or private mapping. + * Don't rearrange members without looking at hash_futex(). + * + * offset is aligned to a multiple of sizeof(u32) (== 4) by definition. + * We set bit 0 to indicate if it's an inode-based key. + */ +union futex_key { + struct { + unsigned long pgoff; + struct inode *inode; + int offset; + } shared; + struct { + unsigned long address; + struct mm_struct *mm; + int offset; + } private; + struct { + unsigned long word; + void *ptr; + int offset; + } both; +}; +int get_futex_key(u32 __user *uaddr, union futex_key *key); +void get_futex_key_refs(union futex_key *key); +void drop_futex_key_refs(union futex_key *key); + #ifdef CONFIG_FUTEX extern void exit_robust_list(struct task_struct *curr); extern void exit_pi_state_list(struct task_struct *curr); =================================================================== --- a/kernel/futex.c +++ b/kernel/futex.c @@ -48,37 +48,12 @@ #include #include #include +#include #include #include "rtmutex_common.h" #define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8) - -/* - * Futexes are matched on equal values of this key. - * The key type depends on whether it's a shared or private mapping. - * Don't rearrange members without looking at hash_futex(). - * - * offset is aligned to a multiple of sizeof(u32) (== 4) by definition. - * We set bit 0 to indicate if it's an inode-based key. - */ -union futex_key { - struct { - unsigned long pgoff; - struct inode *inode; - int offset; - } shared; - struct { - unsigned long address; - struct mm_struct *mm; - int offset; - } private; - struct { - unsigned long word; - void *ptr; - int offset; - } both; -}; /* * Priority Inheritance state: @@ -175,7 +150,7 @@ static inline int match_futex(union fute * * Should be called with ¤t->mm->mmap_sem but NOT any spinlocks. */ -static int get_futex_key(u32 __user *uaddr, union futex_key *key) +int get_futex_key(u32 __user *uaddr, union futex_key *key) { unsigned long address = (unsigned long)uaddr; struct mm_struct *mm = current->mm; @@ -246,6 +221,7 @@ static int get_futex_key(u32 __user *uad } return err; } +EXPORT_SYMBOL_GPL(get_futex_key); /* * Take a reference to the resource addressed by a key. @@ -254,7 +230,7 @@ static int get_futex_key(u32 __user *uad * NOTE: mmap_sem MUST be held between get_futex_key() and calling this * function, if it is called at all. mmap_sem keeps key->shared.inode valid. */ -static inline void get_key_refs(union futex_key *key) +inline void get_futex_key_refs(union futex_key *key) { if (key->both.ptr != 0) { if (key->both.offset & 1) @@ -263,12 +239,13 @@ static inline void get_key_refs(union fu atomic_inc(&key->private.mm->mm_count); } } +EXPORT_SYMBOL_GPL(get_futex_key_refs); /* * Drop a reference to the resource addressed by a key. * The hash bucket spinlock must not be held. */ -static void drop_key_refs(union futex_key *key) +void drop_futex_key_refs(union futex_key *key) { if (key->both.ptr != 0) { if (key->both.offset & 1) @@ -277,6 +254,7 @@ static void drop_key_refs(union futex_ke mmdrop(key->private.mm); } } +EXPORT_SYMBOL_GPL(drop_futex_key_refs); static inline int get_futex_value_locked(u32 *dest, u32 __user *from) { @@ -871,7 +849,7 @@ static int futex_requeue(u32 __user *uad this->lock_ptr = &hb2->lock; } this->key = key2; - get_key_refs(&key2); + get_futex_key_refs(&key2); drop_count++; if (ret - nr_wake >= nr_requeue) @@ -884,9 +862,9 @@ out_unlock: if (hb1 != hb2) spin_unlock(&hb2->lock); - /* drop_key_refs() must be called outside the spinlocks. */ + /* drop_futex_key_refs() must be called outside the spinlocks. */ while (--drop_count >= 0) - drop_key_refs(&key1); + drop_futex_key_refs(&key1); out: up_read(¤t->mm->mmap_sem); @@ -904,7 +882,7 @@ queue_lock(struct futex_q *q, int fd, st init_waitqueue_head(&q->waiters); - get_key_refs(&q->key); + get_futex_key_refs(&q->key); hb = hash_futex(&q->key); q->lock_ptr = &hb->lock; @@ -923,7 +901,7 @@ queue_unlock(struct futex_q *q, struct f queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb) { spin_unlock(&hb->lock); - drop_key_refs(&q->key); + drop_futex_key_refs(&q->key); } /* @@ -978,7 +956,7 @@ static int unqueue_me(struct futex_q *q) ret = 1; } - drop_key_refs(&q->key); + drop_futex_key_refs(&q->key); return ret; } @@ -997,7 +975,7 @@ static void unqueue_me_pi(struct futex_q spin_unlock(&hb->lock); - drop_key_refs(&q->key); + drop_futex_key_refs(&q->key); } static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)