futex: Add sys_futex_wake()

peterz@infradead.org · Peter Zijlstra · commit 9f6c532f59b2 · 2023-09-21T19:22:07.000+02:00
To complement sys_futex_waitv() add sys_futex_wake(). This syscall implements what was previously known as FUTEX_WAKE_BITSET except it uses 'unsigned long' for the bitmask and takes FUTEX2 flags. The 'unsigned long' allows FUTEX2_SIZE_U64 on 64bit platforms. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Link: https://lore.kernel.org/r/20230921105247.936205525@noisy.programming.kicks-ass.net
diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -492,3 +492,4 @@
 560	common	set_mempolicy_home_node		sys_ni_syscall
 561	common	cachestat			sys_cachestat
 562	common	fchmodat2			sys_fchmodat2
+563	common	futex_wake			sys_futex_wake
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
@@ -466,3 +466,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
@@ -39,7 +39,7 @@
 #define __ARM_NR_compat_set_tls		(__ARM_NR_COMPAT_BASE + 5)
 #define __ARM_NR_COMPAT_END		(__ARM_NR_COMPAT_BASE + 0x800)
 
-#define __NR_compat_syscalls		453
+#define __NR_compat_syscalls		455
 #endif
 
 #define __ARCH_WANT_SYS_CLONE
diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
@@ -911,6 +911,8 @@ __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node)
 __SYSCALL(__NR_cachestat, sys_cachestat)
 #define __NR_fchmodat2 452
 __SYSCALL(__NR_fchmodat2, sys_fchmodat2)
+#define __NR_futex_wake 454
+__SYSCALL(__NR_futex_wake, sys_futex_wake)
 
 /*
  * Please add new compat syscalls above this comment and update
diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl
@@ -373,3 +373,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -452,3 +452,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -458,3 +458,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -391,3 +391,4 @@
 450	n32	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	n32	cachestat			sys_cachestat
 452	n32	fchmodat2			sys_fchmodat2
+454	n32	futex_wake			sys_futex_wake
diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -367,3 +367,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	n64	cachestat			sys_cachestat
 452	n64	fchmodat2			sys_fchmodat2
+454	n64	futex_wake			sys_futex_wake
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -440,3 +440,4 @@
 450	o32	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	o32	cachestat			sys_cachestat
 452	o32	fchmodat2			sys_fchmodat2
+454	o32	futex_wake			sys_futex_wake
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -451,3 +451,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -539,3 +539,4 @@
 450 	nospu	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
@@ -455,3 +455,4 @@
 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	fchmodat2		sys_fchmodat2			sys_fchmodat2
+454  common	futex_wake		sys_futex_wake			sys_futex_wake
diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
@@ -455,3 +455,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -498,3 +498,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -457,3 +457,4 @@
 450	i386	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	i386	cachestat		sys_cachestat
 452	i386	fchmodat2		sys_fchmodat2
+454	i386	futex_wake		sys_futex_wake
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -375,6 +375,7 @@
 451	common	cachestat		sys_cachestat
 452	common	fchmodat2		sys_fchmodat2
 453	64	map_shadow_stack	sys_map_shadow_stack
+454	common	futex_wake		sys_futex_wake
 
 #
 # Due to a historical design error, certain syscalls are numbered differently
diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -423,3 +423,4 @@
 450	common	set_mempolicy_home_node		sys_set_mempolicy_home_node
 451	common	cachestat			sys_cachestat
 452	common	fchmodat2			sys_fchmodat2
+454	common	futex_wake			sys_futex_wake
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
@@ -549,6 +549,9 @@ asmlinkage long sys_set_robust_list(struct robust_list_head __user *head,
 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, unsigned long mask, int nr, unsigned int flags);
+
 asmlinkage long sys_nanosleep(struct __kernel_timespec __user *rqtp,
 			      struct __kernel_timespec __user *rmtp);
 asmlinkage long sys_nanosleep_time32(struct old_timespec32 __user *rqtp,
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
@@ -822,9 +822,11 @@ __SYSCALL(__NR_cachestat, sys_cachestat)
 
 #define __NR_fchmodat2 452
 __SYSCALL(__NR_fchmodat2, sys_fchmodat2)
+#define __NR_futex_wake 454
+__SYSCALL(__NR_futex_wake, sys_futex_wake)
 
 #undef __NR_syscalls
-#define __NR_syscalls 453
+#define __NR_syscalls 455
 
 /*
  * 32 bit systems traditionally used different
diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c
@@ -306,6 +306,36 @@ SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters,
 	return ret;
 }
 
+/*
+ * sys_futex_wake - Wake a number of futexes
+ * @uaddr:	Address of the futex(es) to wake
+ * @mask:	bitmask
+ * @nr:		Number of the futexes to wake
+ * @flags:	FUTEX2 flags
+ *
+ * Identical to the traditional FUTEX_WAKE_BITSET op, except it is part of the
+ * futex2 family of calls.
+ */
+
+SYSCALL_DEFINE4(futex_wake,
+		void __user *, uaddr,
+		unsigned long, mask,
+		int, nr,
+		unsigned int, flags)
+{
+	if (flags & ~FUTEX2_VALID_MASK)
+		return -EINVAL;
+
+	flags = futex2_to_flags(flags);
+	if (!futex_flags_valid(flags))
+		return -EINVAL;
+
+	if (!futex_validate_input(flags, mask))
+		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,
diff --git 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);

Original file line number	Diff line number	Diff line change
`@@ -375,6 +375,7 @@`
`375`	`375`	`451 common cachestat sys_cachestat`
`376`	`376`	`452 common fchmodat2 sys_fchmodat2`
`377`	`377`	`453 64 map_shadow_stack sys_map_shadow_stack`
	`378`	`+454 common futex_wake sys_futex_wake`
`378`	`379`
`379`	`380`	`#`
`380`	`381`	`# Due to a historical design error, certain syscalls are numbered differently`