diff options
author | peterz@infradead.org <peterz@infradead.org> | 2023-09-21 13:45:12 +0300 |
---|---|---|
committer | Peter Zijlstra <peterz@infradead.org> | 2023-09-21 20:22:08 +0300 |
commit | cb8c4312afca1b2dc64107e7e7cea81911055612 (patch) | |
tree | 47b639a216151b9f38126bffe53d46cd49cc1e3f /kernel/futex/syscalls.c | |
parent | 43adf844951084c266f172561f84c5f8120dd60b (diff) | |
download | linux-cb8c4312afca1b2dc64107e7e7cea81911055612.tar.xz |
futex: Add sys_futex_wait()
To complement sys_futex_waitv()/wake(), add sys_futex_wait(). This
syscall implements what was previously known as FUTEX_WAIT_BITSET
except it uses 'unsigned long' for the value and bitmask arguments,
takes timespec and clockid_t arguments for the absolute timeout and
uses 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/20230921105248.164324363@noisy.programming.kicks-ass.net
Diffstat (limited to 'kernel/futex/syscalls.c')
-rw-r--r-- | kernel/futex/syscalls.c | 120 |
1 files changed, 90 insertions, 30 deletions
diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 47398926765e..e4c8ec713787 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -221,6 +221,46 @@ static int futex_parse_waitv(struct futex_vector *futexv, return 0; } +static int futex2_setup_timeout(struct __kernel_timespec __user *timeout, + clockid_t clockid, struct hrtimer_sleeper *to) +{ + int flag_clkid = 0, flag_init = 0; + struct timespec64 ts; + ktime_t time; + int ret; + + if (!timeout) + return 0; + + if (clockid == CLOCK_REALTIME) { + flag_clkid = FLAGS_CLOCKRT; + flag_init = FUTEX_CLOCK_REALTIME; + } + + if (clockid != CLOCK_REALTIME && clockid != CLOCK_MONOTONIC) + return -EINVAL; + + if (get_timespec64(&ts, timeout)) + return -EFAULT; + + /* + * Since there's no opcode for futex_waitv, use + * FUTEX_WAIT_BITSET that uses absolute timeout as well + */ + ret = futex_init_timeout(FUTEX_WAIT_BITSET, flag_init, &ts, &time); + if (ret) + return ret; + + futex_setup_timer(&time, to, flag_clkid, 0); + return 0; +} + +static inline void futex2_destroy_timeout(struct hrtimer_sleeper *to) +{ + hrtimer_cancel(&to->timer); + destroy_hrtimer_on_stack(&to->timer); +} + /** * sys_futex_waitv - Wait on a list of futexes * @waiters: List of futexes to wait on @@ -250,8 +290,6 @@ SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters, { struct hrtimer_sleeper to; struct futex_vector *futexv; - struct timespec64 ts; - ktime_t time; int ret; /* This syscall supports no flags for now */ @@ -261,30 +299,8 @@ SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters, if (!nr_futexes || nr_futexes > FUTEX_WAITV_MAX || !waiters) return -EINVAL; - if (timeout) { - int flag_clkid = 0, flag_init = 0; - - if (clockid == CLOCK_REALTIME) { - flag_clkid = FLAGS_CLOCKRT; - flag_init = FUTEX_CLOCK_REALTIME; - } - - if (clockid != CLOCK_REALTIME && clockid != CLOCK_MONOTONIC) - return -EINVAL; - - if (get_timespec64(&ts, timeout)) - return -EFAULT; - - /* - * Since there's no opcode for futex_waitv, use - * FUTEX_WAIT_BITSET that uses absolute timeout as well - */ - ret = futex_init_timeout(FUTEX_WAIT_BITSET, flag_init, &ts, &time); - if (ret) - return ret; - - futex_setup_timer(&time, &to, flag_clkid, 0); - } + if (timeout && (ret = futex2_setup_timeout(timeout, clockid, &to))) + return ret; futexv = kcalloc(nr_futexes, sizeof(*futexv), GFP_KERNEL); if (!futexv) { @@ -299,10 +315,8 @@ SYSCALL_DEFINE5(futex_waitv, struct futex_waitv __user *, waiters, kfree(futexv); destroy_timer: - if (timeout) { - hrtimer_cancel(&to.timer); - destroy_hrtimer_on_stack(&to.timer); - } + if (timeout) + futex2_destroy_timeout(&to); return ret; } @@ -336,6 +350,52 @@ SYSCALL_DEFINE4(futex_wake, return futex_wake(uaddr, FLAGS_STRICT | flags, nr, mask); } +/* + * sys_futex_wait - Wait on a futex + * @uaddr: Address of the futex to wait on + * @val: Value of @uaddr + * @mask: bitmask + * @flags: FUTEX2 flags + * @timeout: Optional absolute timeout + * @clockid: Clock to be used for the timeout, realtime or monotonic + * + * Identical to the traditional FUTEX_WAIT_BITSET op, except it is part of the + * futex2 familiy of calls. + */ + +SYSCALL_DEFINE6(futex_wait, + void __user *, uaddr, + unsigned long, val, + unsigned long, mask, + unsigned int, flags, + struct __kernel_timespec __user *, timeout, + clockid_t, clockid) +{ + struct hrtimer_sleeper to; + int ret; + + if (flags & ~FUTEX2_VALID_MASK) + return -EINVAL; + + flags = futex2_to_flags(flags); + if (!futex_flags_valid(flags)) + return -EINVAL; + + if (!futex_validate_input(flags, val) || + !futex_validate_input(flags, mask)) + return -EINVAL; + + if (timeout && (ret = futex2_setup_timeout(timeout, clockid, &to))) + return ret; + + ret = __futex_wait(uaddr, flags, val, timeout ? &to : NULL, mask); + + if (timeout) + futex2_destroy_timeout(&to); + + return ret; +} + #ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE2(set_robust_list, struct compat_robust_list_head __user *, head, |