Hi Peter,
Em 07/08/2023 09:18, Peter Zijlstra escreveu:
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@xxxxxxxxxxxxx>
Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
---
[...]
+/*
+ * 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)
+{
Do you think we could have a
if (!nr)
return 0;
here? Otherwise, calling futex_wake(&f, 0, flags) will wake 1 futex (if
available), which is a strange undocumented behavior in my opinion.
+ 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,
--- 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);
