linux-kernel - [RFC][PATCH 06/10] futex: Propagate flags into get_futex

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Message-ID: <20230714141219.014386004@infradead.org>
Date:   Fri, 14 Jul 2023 15:39:05 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     tglx@...utronix.de, axboe@...nel.dk
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, dvhart@...radead.org, dave@...olabs.net,
        andrealmeid@...lia.com, Andrew Morton <akpm@...ux-foundation.org>,
        urezki@...il.com, hch@...radead.org, lstoakes@...il.com,
        Arnd Bergmann <arnd@...db.de>, linux-api@...r.kernel.org,
        linux-mm@...ck.org, linux-arch@...r.kernel.org,
        malteskarupke@....de
Subject: [RFC][PATCH 06/10] futex: Propagate flags into get_futex_key()

Instead of only passing FLAGS_SHARED as a boolean, pass down flags as
a whole.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/futex/core.c     |    5 ++++-
 kernel/futex/futex.h    |    2 +-
 kernel/futex/pi.c       |    4 ++--
 kernel/futex/requeue.c  |    6 +++---
 kernel/futex/waitwake.c |   15 ++++++++-------
 5 files changed, 18 insertions(+), 14 deletions(-)

--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -217,7 +217,7 @@ static u64 get_inode_sequence_number(str
  *
  * lock_page() might sleep, the caller should not hold a spinlock.
  */
-int get_futex_key(u32 __user *uaddr, bool fshared, union futex_key *key,
+int get_futex_key(u32 __user *uaddr, unsigned int flags, union futex_key *key,
 		  enum futex_access rw)
 {
 	unsigned long address = (unsigned long)uaddr;
@@ -225,6 +225,9 @@ int get_futex_key(u32 __user *uaddr, boo
 	struct page *page, *tail;
 	struct address_space *mapping;
 	int err, ro = 0;
+	bool fshared;
+
+	fshared = flags & FLAGS_SHARED;
 
 	/*
 	 * The futex address must be "naturally" aligned.
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -158,7 +158,7 @@ enum futex_access {
 	FUTEX_WRITE
 };
 
-extern int get_futex_key(u32 __user *uaddr, bool fshared, union futex_key *key,
+extern int get_futex_key(u32 __user *uaddr, unsigned int flags, union futex_key *key,
 			 enum futex_access rw);
 
 extern struct hrtimer_sleeper *
--- a/kernel/futex/pi.c
+++ b/kernel/futex/pi.c
@@ -945,7 +945,7 @@ int futex_lock_pi(u32 __user *uaddr, uns
 	to = futex_setup_timer(time, &timeout, flags, 0);
 
 retry:
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key, FUTEX_WRITE);
+	ret = get_futex_key(uaddr, flags, &q.key, FUTEX_WRITE);
 	if (unlikely(ret != 0))
 		goto out;
 
@@ -1117,7 +1117,7 @@ int futex_unlock_pi(u32 __user *uaddr, u
 	if ((uval & FUTEX_TID_MASK) != vpid)
 		return -EPERM;
 
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, FUTEX_WRITE);
+	ret = get_futex_key(uaddr, flags, &key, FUTEX_WRITE);
 	if (ret)
 		return ret;
 
--- a/kernel/futex/requeue.c
+++ b/kernel/futex/requeue.c
@@ -424,10 +424,10 @@ int futex_requeue(u32 __user *uaddr1, un
 	}
 
 retry:
-	ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, FUTEX_READ);
+	ret = get_futex_key(uaddr1, flags, &key1, FUTEX_READ);
 	if (unlikely(ret != 0))
 		return ret;
-	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2,
+	ret = get_futex_key(uaddr2, flags, &key2,
 			    requeue_pi ? FUTEX_WRITE : FUTEX_READ);
 	if (unlikely(ret != 0))
 		return ret;
@@ -789,7 +789,7 @@ int futex_wait_requeue_pi(u32 __user *ua
 	 */
 	rt_mutex_init_waiter(&rt_waiter);
 
-	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, FUTEX_WRITE);
+	ret = get_futex_key(uaddr2, flags, &key2, FUTEX_WRITE);
 	if (unlikely(ret != 0))
 		goto out;
 
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -145,13 +145,13 @@ int futex_wake(u32 __user *uaddr, unsign
 	struct futex_hash_bucket *hb;
 	struct futex_q *this, *next;
 	union futex_key key = FUTEX_KEY_INIT;
-	int ret;
 	DEFINE_WAKE_Q(wake_q);
+	int ret;
 
 	if (!bitset)
 		return -EINVAL;
 
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key, FUTEX_READ);
+	ret = get_futex_key(uaddr, flags, &key, FUTEX_READ);
 	if (unlikely(ret != 0))
 		return ret;
 
@@ -245,10 +245,10 @@ int futex_wake_op(u32 __user *uaddr1, un
 	DEFINE_WAKE_Q(wake_q);
 
 retry:
-	ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1, FUTEX_READ);
+	ret = get_futex_key(uaddr1, flags, &key1, FUTEX_READ);
 	if (unlikely(ret != 0))
 		return ret;
-	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, FUTEX_WRITE);
+	ret = get_futex_key(uaddr2, flags, &key2, FUTEX_WRITE);
 	if (unlikely(ret != 0))
 		return ret;
 
@@ -423,7 +423,7 @@ static int futex_wait_multiple_setup(str
 			continue;
 
 		ret = get_futex_key(u64_to_user_ptr(vs[i].w.uaddr),
-				    vs[i].w.flags & FLAGS_SHARED,
+				    vs[i].w.flags,
 				    &vs[i].q.key, FUTEX_READ);
 
 		if (unlikely(ret))
@@ -435,7 +435,8 @@ static int futex_wait_multiple_setup(str
 	for (i = 0; i < count; i++) {
 		u32 __user *uaddr = (u32 __user *)(unsigned long)vs[i].w.uaddr;
 		struct futex_q *q = &vs[i].q;
-		u32 val = (u32)vs[i].w.val;
+		unsigned int flags = vs[i].w.flags;
+		u32 val = vs[i].w.val;
 
 		hb = futex_q_lock(q);
 		ret = futex_get_value_locked(&uval, uaddr);
@@ -599,7 +600,7 @@ int futex_wait_setup(u32 __user *uaddr,
 	 * while the syscall executes.
 	 */
 retry:
-	ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key, FUTEX_READ);
+	ret = get_futex_key(uaddr, flags, &q->key, FUTEX_READ);
 	if (unlikely(ret != 0))
 		return ret;