Finish off the 'simple' futex2 syscall group by adding
sys_futex_requeue(). Unlike sys_futex_{wait,wake}() its arguments are
too numerous to fit into a regular syscall. As such, use struct
futex_waitv to pass the 'source' and 'destination' futexes to the
syscall.
This syscall implements what was previously known as FUTEX_CMP_REQUEUE
and uses {val, uaddr, flags} for source and {uaddr, flags} for
destination.
This design explicitly allows requeueing between different types of
futex by having a different flags word per uaddr.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
---
arch/alpha/kernel/syscalls/syscall.tbl | 1
arch/arm/tools/syscall.tbl | 1
arch/arm64/include/asm/unistd.h | 2 -
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 | 4 ++
kernel/futex/syscalls.c | 38 ++++++++++++++++++++++++++++
kernel/sys_ni.c | 1
22 files changed, 64 insertions(+), 2 deletions(-)
Index: linux-2.6/arch/alpha/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/alpha/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/alpha/kernel/syscalls/syscall.tbl
@@ -494,3 +494,4 @@
562 common fchmodat2 sys_fchmodat2
563 common futex_wake sys_futex_wake
564 common futex_wait sys_futex_wait
+565 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/arm/tools/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/arm/tools/syscall.tbl
+++ linux-2.6/arch/arm/tools/syscall.tbl
@@ -468,3 +468,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/arm64/include/asm/unistd.h
===================================================================
--- linux-2.6.orig/arch/arm64/include/asm/unistd.h
+++ linux-2.6/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 456
+#define __NR_compat_syscalls 457
#endif
#define __ARCH_WANT_SYS_CLONE
Index: linux-2.6/arch/arm64/include/asm/unistd32.h
===================================================================
--- linux-2.6.orig/arch/arm64/include/asm/unistd32.h
+++ linux-2.6/arch/arm64/include/asm/unistd32.h
@@ -915,6 +915,8 @@ __SYSCALL(__NR_fchmodat2, sys_fchmodat2)
__SYSCALL(__NR_futex_wake, sys_futex_wake)
#define __NR_futex_wait 455
__SYSCALL(__NR_futex_wait, sys_futex_wait)
+#define __NR_futex_requeue 456
+__SYSCALL(__NR_futex_requeue, sys_futex_requeue)
/*
* Please add new compat syscalls above this comment and update
Index: linux-2.6/arch/ia64/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/ia64/kernel/syscalls/syscall.tbl
@@ -375,3 +375,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/m68k/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/m68k/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/m68k/kernel/syscalls/syscall.tbl
@@ -454,3 +454,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/microblaze/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/microblaze/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -460,3 +460,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/mips/kernel/syscalls/syscall_n32.tbl
===================================================================
--- linux-2.6.orig/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ linux-2.6/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -393,3 +393,4 @@
452 n32 fchmodat2 sys_fchmodat2
454 n32 futex_wake sys_futex_wake
455 n32 futex_wait sys_futex_wait
+456 n32 futex_requeue sys_futex_requeue
Index: linux-2.6/arch/mips/kernel/syscalls/syscall_n64.tbl
===================================================================
--- linux-2.6.orig/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ linux-2.6/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -369,3 +369,4 @@
452 n64 fchmodat2 sys_fchmodat2
454 n64 futex_wake sys_futex_wake
455 n64 futex_wait sys_futex_wait
+456 n64 futex_requeue sys_futex_requeue
Index: linux-2.6/arch/mips/kernel/syscalls/syscall_o32.tbl
===================================================================
--- linux-2.6.orig/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ linux-2.6/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -442,3 +442,4 @@
452 o32 fchmodat2 sys_fchmodat2
454 o32 futex_wake sys_futex_wake
455 o32 futex_wait sys_futex_wait
+456 o32 futex_requeue sys_futex_requeue
Index: linux-2.6/arch/parisc/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/parisc/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/parisc/kernel/syscalls/syscall.tbl
@@ -453,3 +453,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/powerpc/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -541,3 +541,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/s390/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/s390/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/s390/kernel/syscalls/syscall.tbl
@@ -457,3 +457,4 @@
452 common fchmodat2 sys_fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue sys_futex_requeue
Index: linux-2.6/arch/sh/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/sh/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/sh/kernel/syscalls/syscall.tbl
@@ -457,3 +457,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/sparc/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/sparc/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/sparc/kernel/syscalls/syscall.tbl
@@ -500,3 +500,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/arch/x86/entry/syscalls/syscall_32.tbl
===================================================================
--- linux-2.6.orig/arch/x86/entry/syscalls/syscall_32.tbl
+++ linux-2.6/arch/x86/entry/syscalls/syscall_32.tbl
@@ -459,3 +459,4 @@
452 i386 fchmodat2 sys_fchmodat2
454 i386 futex_wake sys_futex_wake
455 i386 futex_wait sys_futex_wait
+456 i386 futex_requeue sys_futex_requeue
Index: linux-2.6/arch/x86/entry/syscalls/syscall_64.tbl
===================================================================
--- linux-2.6.orig/arch/x86/entry/syscalls/syscall_64.tbl
+++ linux-2.6/arch/x86/entry/syscalls/syscall_64.tbl
@@ -377,6 +377,7 @@
453 64 map_shadow_stack sys_map_shadow_stack
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
#
# Due to a historical design error, certain syscalls are numbered differently
Index: linux-2.6/arch/xtensa/kernel/syscalls/syscall.tbl
===================================================================
--- linux-2.6.orig/arch/xtensa/kernel/syscalls/syscall.tbl
+++ linux-2.6/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -425,3 +425,4 @@
452 common fchmodat2 sys_fchmodat2
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
+456 common futex_requeue sys_futex_requeue
Index: linux-2.6/include/linux/syscalls.h
===================================================================
--- linux-2.6.orig/include/linux/syscalls.h
+++ linux-2.6/include/linux/syscalls.h
@@ -556,6 +556,9 @@ asmlinkage long sys_futex_wait(void __us
unsigned int flags, struct __kernel_timespec __user *timespec,
clockid_t clockid);
+asmlinkage long sys_futex_requeue(struct futex_waitv __user *waiters,
+ unsigned int flags, int nr_wake, int nr_requeue);
+
asmlinkage long sys_nanosleep(struct __kernel_timespec __user *rqtp,
struct __kernel_timespec __user *rmtp);
asmlinkage long sys_nanosleep_time32(struct old_timespec32 __user *rqtp,
Index: linux-2.6/include/uapi/asm-generic/unistd.h
===================================================================
--- linux-2.6.orig/include/uapi/asm-generic/unistd.h
+++ linux-2.6/include/uapi/asm-generic/unistd.h
@@ -826,9 +826,11 @@ __SYSCALL(__NR_fchmodat2, sys_fchmodat2)
__SYSCALL(__NR_futex_wake, sys_futex_wake)
#define __NR_futex_wait 455
__SYSCALL(__NR_futex_wait, sys_futex_wait)
+#define __NR_futex_requeue 456
+__SYSCALL(__NR_futex_requeue, sys_futex_requeue)
#undef __NR_syscalls
-#define __NR_syscalls 456
+#define __NR_syscalls 457
/*
* 32 bit systems traditionally used different
Index: linux-2.6/kernel/futex/syscalls.c
===================================================================
--- linux-2.6.orig/kernel/futex/syscalls.c
+++ linux-2.6/kernel/futex/syscalls.c
@@ -396,6 +396,44 @@ SYSCALL_DEFINE6(futex_wait,
return ret;
}
+/*
+ * sys_futex_requeue - Requeue a waiter from one futex to another
+ * @waiters: array describing the source and destination futex
+ * @flags: unused
+ * @nr_wake: number of futexes to wake
+ * @nr_requeue: number of futexes to requeue
+ *
+ * Identical to the traditional FUTEX_CMP_REQUEUE op, except it is part of the
+ * futex2 family of calls.
+ */
+
+SYSCALL_DEFINE4(futex_requeue,
+ struct futex_waitv __user *, waiters,
+ unsigned int, flags,
+ int, nr_wake,
+ int, nr_requeue)
+{
+ struct futex_vector futexes[2];
+ u32 cmpval;
+ int ret;
+
+ if (flags)
+ return -EINVAL;
+
+ if (!waiters)
+ return -EINVAL;
+
+ ret = futex_parse_waitv(futexes, waiters, 2);
+ if (ret)
+ return ret;
+
+ cmpval = futexes[0].w.val;
+
+ return futex_requeue(u64_to_user_ptr(futexes[0].w.uaddr), futexes[0].w.flags,
+ u64_to_user_ptr(futexes[1].w.uaddr), futexes[1].w.flags,
+ nr_wake, nr_requeue, &cmpval, 0);
+}
+
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(set_robust_list,
struct compat_robust_list_head __user *, head,
Index: linux-2.6/kernel/sys_ni.c
===================================================================
--- linux-2.6.orig/kernel/sys_ni.c
+++ linux-2.6/kernel/sys_ni.c
@@ -89,6 +89,7 @@ COND_SYSCALL_COMPAT(get_robust_list);
COND_SYSCALL(futex_waitv);
COND_SYSCALL(futex_wake);
COND_SYSCALL(futex_wait);
+COND_SYSCALL(futex_requeue);
COND_SYSCALL(kexec_load);
COND_SYSCALL_COMPAT(kexec_load);
COND_SYSCALL(init_module);
* [email protected] <[email protected]> wrote:
> --- linux-2.6.orig/kernel/futex/syscalls.c
> +++ linux-2.6/kernel/futex/syscalls.c
> @@ -396,6 +396,44 @@ SYSCALL_DEFINE6(futex_wait,
> return ret;
> }
>
> +/*
> + * sys_futex_requeue - Requeue a waiter from one futex to another
> + * @waiters: array describing the source and destination futex
> + * @flags: unused
> + * @nr_wake: number of futexes to wake
> + * @nr_requeue: number of futexes to requeue
> + *
> + * Identical to the traditional FUTEX_CMP_REQUEUE op, except it is part of the
> + * futex2 family of calls.
> + */
> +
> +SYSCALL_DEFINE4(futex_requeue,
> + struct futex_waitv __user *, waiters,
> + unsigned int, flags,
> + int, nr_wake,
> + int, nr_requeue)
> +{
> + struct futex_vector futexes[2];
> + u32 cmpval;
> + int ret;
> +
> + if (flags)
> + return -EINVAL;
Small detail, but isn't -ENOSYS the canonical error code for functionality
not yet implemented - which the unused 'flags' ABI is arguably?
-EINVAL is for recognized but incorrect parameters, such as:
> + if (!waiters)
> + return -EINVAL;
Thanks,
Ingo
On Fri, Sep 22, 2023 at 11:35:03AM +0200, Ingo Molnar wrote:
>
> * [email protected] <[email protected]> wrote:
>
> > --- linux-2.6.orig/kernel/futex/syscalls.c
> > +++ linux-2.6/kernel/futex/syscalls.c
> > @@ -396,6 +396,44 @@ SYSCALL_DEFINE6(futex_wait,
> > return ret;
> > }
> >
> > +/*
> > + * sys_futex_requeue - Requeue a waiter from one futex to another
> > + * @waiters: array describing the source and destination futex
> > + * @flags: unused
> > + * @nr_wake: number of futexes to wake
> > + * @nr_requeue: number of futexes to requeue
> > + *
> > + * Identical to the traditional FUTEX_CMP_REQUEUE op, except it is part of the
> > + * futex2 family of calls.
> > + */
> > +
> > +SYSCALL_DEFINE4(futex_requeue,
> > + struct futex_waitv __user *, waiters,
> > + unsigned int, flags,
> > + int, nr_wake,
> > + int, nr_requeue)
> > +{
> > + struct futex_vector futexes[2];
> > + u32 cmpval;
> > + int ret;
> > +
> > + if (flags)
> > + return -EINVAL;
>
> Small detail, but isn't -ENOSYS the canonical error code for functionality
> not yet implemented - which the unused 'flags' ABI is arguably?
>
> -EINVAL is for recognized but incorrect parameters, such as:
IIUC 'unknown flag' falls into the -EINVAL return category. Here we
happen to have no known flags, but that should not matter.
On 9/22/23 5:03 AM, Peter Zijlstra wrote:
> On Fri, Sep 22, 2023 at 11:35:03AM +0200, Ingo Molnar wrote:
>>
>> * [email protected] <[email protected]> wrote:
>>
>>> --- linux-2.6.orig/kernel/futex/syscalls.c
>>> +++ linux-2.6/kernel/futex/syscalls.c
>>> @@ -396,6 +396,44 @@ SYSCALL_DEFINE6(futex_wait,
>>> return ret;
>>> }
>>>
>>> +/*
>>> + * sys_futex_requeue - Requeue a waiter from one futex to another
>>> + * @waiters: array describing the source and destination futex
>>> + * @flags: unused
>>> + * @nr_wake: number of futexes to wake
>>> + * @nr_requeue: number of futexes to requeue
>>> + *
>>> + * Identical to the traditional FUTEX_CMP_REQUEUE op, except it is part of the
>>> + * futex2 family of calls.
>>> + */
>>> +
>>> +SYSCALL_DEFINE4(futex_requeue,
>>> + struct futex_waitv __user *, waiters,
>>> + unsigned int, flags,
>>> + int, nr_wake,
>>> + int, nr_requeue)
>>> +{
>>> + struct futex_vector futexes[2];
>>> + u32 cmpval;
>>> + int ret;
>>> +
>>> + if (flags)
>>> + return -EINVAL;
>>
>> Small detail, but isn't -ENOSYS the canonical error code for functionality
>> not yet implemented - which the unused 'flags' ABI is arguably?
>>
>> -EINVAL is for recognized but incorrect parameters, such as:
>
> IIUC 'unknown flag' falls into the -EINVAL return category. Here we
> happen to have no known flags, but that should not matter.
Yep, -ENOSYS is for not having the syscall at all, -EINVAL for unknown
flags set.
--
Jens Axboe