From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, axboe@kernel.dk
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
mingo@redhat.com, dvhart@infradead.org, dave@stgolabs.net,
andrealmeid@igalia.com, Andrew Morton <akpm@linux-foundation.org>,
urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com,
Arnd Bergmann <arnd@arndb.de>,
linux-api@vger.kernel.org, linux-mm@kvack.org,
linux-arch@vger.kernel.org, malteskarupke@web.de
Subject: [PATCH v2 01/14] futex: Clarify FUTEX2 flags
Date: Mon, 07 Aug 2023 14:18:44 +0200 [thread overview]
Message-ID: <20230807123322.814039156@infradead.org> (raw)
In-Reply-To: 20230807121843.710612856@infradead.org
sys_futex_waitv() is part of the futex2 series (the first and only so
far) of syscalls and has a flags field per futex (as opposed to flags
being encoded in the futex op).
This new flags field has a new namespace, which unfortunately isn't
super explicit. Notably it currently takes FUTEX_32 and
FUTEX_PRIVATE_FLAG.
Introduce the FUTEX2 namespace to clarify this
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
include/uapi/linux/futex.h | 16 +++++++++++++---
kernel/futex/syscalls.c | 7 +++----
2 files changed, 16 insertions(+), 7 deletions(-)
--- a/include/uapi/linux/futex.h
+++ b/include/uapi/linux/futex.h
@@ -44,10 +44,20 @@
FUTEX_PRIVATE_FLAG)
/*
- * Flags to specify the bit length of the futex word for futex2 syscalls.
- * Currently, only 32 is supported.
+ * Flags for futex2 syscalls.
*/
-#define FUTEX_32 2
+ /* 0x00 */
+ /* 0x01 */
+#define FUTEX2_SIZE_U32 0x02
+ /* 0x04 */
+ /* 0x08 */
+ /* 0x10 */
+ /* 0x20 */
+ /* 0x40 */
+#define FUTEX2_PRIVATE FUTEX_PRIVATE_FLAG
+
+/* do not use */
+#define FUTEX_32 FUTEX2_SIZE_U32 /* historical accident :-( */
/*
* Max numbers of elements in a futex_waitv array
--- a/kernel/futex/syscalls.c
+++ b/kernel/futex/syscalls.c
@@ -183,8 +183,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uad
return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
}
-/* Mask of available flags for each futex in futex_waitv list */
-#define FUTEXV_WAITER_MASK (FUTEX_32 | FUTEX_PRIVATE_FLAG)
+#define FUTEX2_VALID_MASK (FUTEX2_SIZE_U32 | FUTEX2_PRIVATE)
/**
* futex_parse_waitv - Parse a waitv array from userspace
@@ -205,10 +204,10 @@ static int futex_parse_waitv(struct fute
if (copy_from_user(&aux, &uwaitv[i], sizeof(aux)))
return -EFAULT;
- if ((aux.flags & ~FUTEXV_WAITER_MASK) || aux.__reserved)
+ if ((aux.flags & ~FUTEX2_VALID_MASK) || aux.__reserved)
return -EINVAL;
- if (!(aux.flags & FUTEX_32))
+ if (!(aux.flags & FUTEX2_SIZE_U32))
return -EINVAL;
futexv[i].w.flags = aux.flags;
next prev parent reply other threads:[~2023-08-07 12:37 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-07 12:18 [PATCH v2 00/14] futex: More futex2 bits Peter Zijlstra
2023-08-07 12:18 ` Peter Zijlstra [this message]
2023-08-07 23:51 ` [PATCH v2 01/14] futex: Clarify FUTEX2 flags André Almeida
2023-08-07 12:18 ` [PATCH v2 02/14] futex: Extend the " Peter Zijlstra
2023-08-07 18:56 ` Thomas Gleixner
2023-08-08 0:02 ` André Almeida
2023-08-07 12:18 ` [PATCH v2 03/14] futex: Flag conversion Peter Zijlstra
2023-08-07 18:58 ` Thomas Gleixner
2023-08-08 0:52 ` André Almeida
2023-08-07 12:18 ` [PATCH v2 04/14] futex: Validate futex value against futex size Peter Zijlstra
2023-08-07 12:18 ` [PATCH v2 05/14] futex: Add sys_futex_wake() Peter Zijlstra
2023-08-07 19:00 ` Thomas Gleixner
2023-08-09 22:25 ` André Almeida
2023-08-10 12:13 ` Peter Zijlstra
2023-08-10 17:01 ` André Almeida
2023-08-07 12:18 ` [PATCH v2 06/14] futex: Add sys_futex_wait() Peter Zijlstra
2023-08-07 12:18 ` [PATCH v2 07/14] futex: Propagate flags into get_futex_key() Peter Zijlstra
2023-08-07 12:18 ` [PATCH v2 08/14] futex: Add flags2 argument to futex_requeue() Peter Zijlstra
2023-08-07 19:01 ` Thomas Gleixner
2023-08-07 12:18 ` [PATCH v2 09/14] futex: Add sys_futex_requeue() Peter Zijlstra
2023-08-07 19:05 ` Thomas Gleixner
2023-08-07 12:18 ` [PATCH v2 10/14] mm: Add vmalloc_huge_node() Peter Zijlstra
2023-08-07 12:18 ` [PATCH v2 11/14] futex: Implement FUTEX2_NUMA Peter Zijlstra
2023-08-07 21:11 ` Thomas Gleixner
2023-08-08 8:54 ` Peter Zijlstra
2023-08-08 9:12 ` Thomas Gleixner
2023-08-07 12:18 ` [PATCH v2 12/14] futex: Propagate flags into futex_get_value_locked() Peter Zijlstra
2023-08-07 21:12 ` Thomas Gleixner
2023-08-07 12:18 ` [PATCH v2 13/14] futex: Enable FUTEX2_{8,16} Peter Zijlstra
2023-08-07 21:15 ` Thomas Gleixner
2023-08-07 12:18 ` [PATCH v2 14/14] futex,selftests: Extend the futex selftests Peter Zijlstra
2023-08-08 20:32 ` [PATCH v2 00/14] futex: More futex2 bits Jens Axboe
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