The following commit has been merged into the locking/core branch of tip: Commit-ID: 4923954bbc4a760e0b2210e0cb5733726ac2e2e9 Gitweb: https://git.kernel.org/tip/4923954bbc4a760e0b2210e0cb5733726ac2e2e9 Author: peterz@xxxxxxxxxxxxx <peterz@xxxxxxxxxxxxx> AuthorDate: Thu, 21 Sep 2023 12:45:06 +02:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Thu, 21 Sep 2023 19:22:04 +02:00 futex: Clarify FUTEX2 flags 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@xxxxxxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Reviewed-by: André Almeida <andrealmeid@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230921105247.507327749@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx --- include/uapi/linux/futex.h | 16 +++++++++++++--- kernel/futex/syscalls.c | 7 +++---- 2 files changed, 16 insertions(+), 7 deletions(-) diff --git a/include/uapi/linux/futex.h b/include/uapi/linux/futex.h index 71a5df8..21d4eff 100644 --- 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 diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index a807407..ff696b0 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -183,8 +183,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, 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 futex_vector *futexv, 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;
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