| Message ID | 20230921105248.511860556@noisy.programming.kicks-ass.net (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | futex: More futex2 bits | expand |
* peterz@infradead.org <peterz@infradead.org> 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: > > * peterz@infradead.org <peterz@infradead.org> 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: >> >> * peterz@infradead.org <peterz@infradead.org> 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.
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);
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) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> --- 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(-)