[RFC][PATCH 04/10] futex: Add sys_futex_wake()

From: Peter Zijlstra
Date: Fri Jul 14 2023 - 10:16:54 EST

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Next in thread: Arnd Bergmann: "Re: [RFC][PATCH 04/10] futex: Add sys_futex_wake()"
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To complement sys_futex_waitv() add sys_futex_wake(). Together they
provide the basic Futex2 WAIT/WAKE functionality.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/alpha/kernel/syscalls/syscall.tbl | 1
arch/arm/tools/syscall.tbl | 1
arch/arm64/include/asm/unistd32.h | 2 +
arch/ia64/kernel/syscalls/syscall.tbl | 1
arch/m68k/kernel/syscalls/syscall.tbl | 1
arch/microblaze/kernel/syscalls/syscall.tbl | 1
arch/mips/kernel/syscalls/syscall_n32.tbl | 1
arch/mips/kernel/syscalls/syscall_n64.tbl | 1
arch/mips/kernel/syscalls/syscall_o32.tbl | 1
arch/parisc/kernel/syscalls/syscall.tbl | 1
arch/powerpc/kernel/syscalls/syscall.tbl | 1
arch/s390/kernel/syscalls/syscall.tbl | 1
arch/sh/kernel/syscalls/syscall.tbl | 1
arch/sparc/kernel/syscalls/syscall.tbl | 1
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
arch/xtensa/kernel/syscalls/syscall.tbl | 1
include/linux/syscalls.h | 3 ++
include/uapi/asm-generic/unistd.h | 5 ++-
kernel/futex/syscalls.c | 37 ++++++++++++++++++++++++++++
kernel/sys_ni.c | 1
21 files changed, 62 insertions(+), 2 deletions(-)

--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -491,3 +491,4 @@
559 common futex_waitv sys_futex_waitv
560 common set_mempolicy_home_node sys_ni_syscall
561 common cachestat sys_cachestat
+562 common futex_wake sys_futex_wake
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -465,3 +465,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -909,6 +909,8 @@ __SYSCALL(__NR_futex_waitv, sys_futex_wa
__SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node)
#define __NR_cachestat 451
__SYSCALL(__NR_cachestat, sys_cachestat)
+#define __NR_futex_wake 452
+__SYSCALL(__NR_futex_wake, sys_futex_wake)

/*
* Please add new compat syscalls above this comment and update
--- a/arch/ia64/kernel/syscalls/syscall.tbl
+++ b/arch/ia64/kernel/syscalls/syscall.tbl
@@ -372,3 +372,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -451,3 +451,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -457,3 +457,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -390,3 +390,4 @@
449 n32 futex_waitv sys_futex_waitv
450 n32 set_mempolicy_home_node sys_set_mempolicy_home_node
451 n32 cachestat sys_cachestat
+452 n32 futex_wake sys_futex_wake
--- a/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -366,3 +366,4 @@
449 n64 futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 n64 cachestat sys_cachestat
+452 n64 futex_wake sys_futex_wake
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -439,3 +439,4 @@
449 o32 futex_waitv sys_futex_waitv
450 o32 set_mempolicy_home_node sys_set_mempolicy_home_node
451 o32 cachestat sys_cachestat
+452 o32 futex_wake sys_futex_wake
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -450,3 +450,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -538,3 +538,4 @@
449 common futex_waitv sys_futex_waitv
450 nospu set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -454,3 +454,4 @@
449 common futex_waitv sys_futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat sys_cachestat
+452 common futex_wake sys_futex_wake sys_futex_wake
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl
@@ -454,3 +454,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -497,3 +497,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -456,3 +456,4 @@
449 i386 futex_waitv sys_futex_waitv
450 i386 set_mempolicy_home_node sys_set_mempolicy_home_node
451 i386 cachestat sys_cachestat
+452 i386 futex_wake sys_futex_wake
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -373,6 +373,7 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake

#
# Due to a historical design error, certain syscalls are numbered differently
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -422,3 +422,4 @@
449 common futex_waitv sys_futex_waitv
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
+452 common futex_wake sys_futex_wake
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -563,6 +563,9 @@ asmlinkage long sys_set_robust_list(stru
asmlinkage long sys_futex_waitv(struct futex_waitv *waiters,
unsigned int nr_futexes, unsigned int flags,
struct __kernel_timespec __user *timeout, clockid_t clockid);
+
+asmlinkage long sys_futex_wake(void __user *uaddr, int nr, unsigned int flags, u64 mask);
+
asmlinkage long sys_nanosleep(struct __kernel_timespec __user *rqtp,
struct __kernel_timespec __user *rmtp);
asmlinkage long sys_nanosleep_time32(struct old_timespec32 __user *rqtp,
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -816,12 +816,13 @@ __SYSCALL(__NR_process_mrelease, sys_pro
__SYSCALL(__NR_futex_waitv, sys_futex_waitv)
#define __NR_set_mempolicy_home_node 450
__SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node)
-
#define __NR_cachestat 451
__SYSCALL(__NR_cachestat, sys_cachestat)
+#define __NR_futex_wake 452
+__SYSCALL(__NR_futex_wake, sys_futex_wake)

#undef __NR_syscalls
-#define __NR_syscalls 452
+#define __NR_syscalls 453

/*
* 32 bit systems traditionally used different
--- a/kernel/futex/syscalls.c
+++ b/kernel/futex/syscalls.c
@@ -309,6 +309,43 @@ SYSCALL_DEFINE5(futex_waitv, struct fute
return ret;
}

+/*
+ * sys_futex_wake - Wake a number of futexes
+ * @uaddr: Address of the futex(es) to wake
+ * @nr: Number of the futexes to wake
+ * @flags: FUTEX2 flags
+ * @mask: bitmask
+ *
+ * Identical to the traditional FUTEX_WAKE_BITSET op, except it matches futex_waitv() above
+ * in that it enables u64 futex values and has a new flags set.
+ *
+ * NOTE: u64 futexes are not actually supported yet, but both these interfaces
+ * should allow for this to happen.
+ */
+
+SYSCALL_DEFINE4(futex_wake,
+ void __user *, uaddr,
+ int, nr,
+ unsigned int, flags,
+ u64, mask)
+{
+ int bits;
+
+ if (flags & ~FUTEX2_MASK)
+ return -EINVAL;
+
+ if ((flags & FUTEX2_64) != FUTEX2_32)
+ return -EINVAL;
+
+ flags = futex2_to_flags(flags);
+ bits = 8 * futex_size(flags);
+
+ if (bits < 64 && mask >> bits)
+ return -EINVAL;
+
+ return futex_wake(uaddr, flags, nr, mask);
+}
+
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(set_robust_list,
struct compat_robust_list_head __user *, head,
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -87,6 +87,7 @@ COND_SYSCALL_COMPAT(set_robust_list);
COND_SYSCALL(get_robust_list);
COND_SYSCALL_COMPAT(get_robust_list);
COND_SYSCALL(futex_waitv);
+COND_SYSCALL(futex_wake);
COND_SYSCALL(kexec_load);
COND_SYSCALL_COMPAT(kexec_load);
COND_SYSCALL(init_module);

Next message: Peter Zijlstra: "[RFC][PATCH 03/10] futex: Flag conversion"
Previous message: Peter Zijlstra: "[RFC][PATCH 08/10] futex: Propagate flags into futex_get_value_locked()"
In reply to: Peter Zijlstra: "[RFC][PATCH 08/10] futex: Propagate flags into futex_get_value_locked()"
Next in thread: Arnd Bergmann: "Re: [RFC][PATCH 04/10] futex: Add sys_futex_wake()"
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