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authorAndré Almeida <andrealmeid@collabora.com>2021-09-23 14:11:05 -0300
committerPeter Zijlstra <peterz@infradead.org>2021-10-07 13:51:11 +0200
commitbf69bad38cf63d980e8a603f8d1bd1f85b5ed3d9 (patch)
treef907feaaea19142964447402ced97a233fbbcb53 /include/uapi/asm-generic/unistd.h
parentbff7c57c2f50dca7b5e320f499e0898c3fb8a9ff (diff)
downloadlinux-bf69bad38cf63d980e8a603f8d1bd1f85b5ed3d9.tar.bz2
futex: Implement sys_futex_waitv()
Add support to wait on multiple futexes. This is the interface implemented by this syscall: futex_waitv(struct futex_waitv *waiters, unsigned int nr_futexes, unsigned int flags, struct timespec *timeout, clockid_t clockid) struct futex_waitv { __u64 val; __u64 uaddr; __u32 flags; __u32 __reserved; }; Given an array of struct futex_waitv, wait on each uaddr. The thread wakes if a futex_wake() is performed at any uaddr. The syscall returns immediately if any waiter has *uaddr != val. *timeout is an optional absolute timeout value for the operation. This syscall supports only 64bit sized timeout structs. The flags argument of the syscall should be empty, but it can be used for future extensions. Flags for shared futexes, sizes, etc. should be used on the individual flags of each waiter. __reserved is used for explicit padding and should be 0, but it might be used for future extensions. If the userspace uses 32-bit pointers, it should make sure to explicitly cast it when assigning to waitv::uaddr. Returns the array index of one of the woken futexes. There’s no given information of how many were woken, or any particular attribute of it (if it’s the first woken, if it is of the smaller index...). Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210923171111.300673-17-andrealmeid@collabora.com
Diffstat (limited to 'include/uapi/asm-generic/unistd.h')
-rw-r--r--include/uapi/asm-generic/unistd.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 1c5fb86d455a..4557a8b6086f 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -880,8 +880,11 @@ __SYSCALL(__NR_memfd_secret, sys_memfd_secret)
#define __NR_process_mrelease 448
__SYSCALL(__NR_process_mrelease, sys_process_mrelease)
+#define __NR_futex_waitv 449
+__SYSCALL(__NR_futex_waitv, sys_futex_waitv)
+
#undef __NR_syscalls
-#define __NR_syscalls 449
+#define __NR_syscalls 450
/*
* 32 bit systems traditionally used different