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authorpeterz@infradead.org <peterz@infradead.org>2023-09-21 12:45:12 +0200
committerPeter Zijlstra <peterz@infradead.org>2023-09-21 19:22:08 +0200
commitcb8c4312afca1b2dc64107e7e7cea81911055612 (patch)
tree47b639a216151b9f38126bffe53d46cd49cc1e3f /kernel/futex
parent43adf844951084c266f172561f84c5f8120dd60b (diff)
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')
-rw-r--r--kernel/futex/futex.h3
-rw-r--r--kernel/futex/syscalls.c120
-rw-r--r--kernel/futex/waitwake.c61
3 files changed, 129 insertions, 55 deletions
diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h
index 0e7821a944a2..e74888a7d71d 100644
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -332,6 +332,9 @@ extern int futex_requeue(u32 __user *uaddr1, unsigned int flags,
u32 __user *uaddr2, int nr_wake, int nr_requeue,
u32 *cmpval, int requeue_pi);
+extern int __futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
+ struct hrtimer_sleeper *to, u32 bitset);
+
extern int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
ktime_t *abs_time, u32 bitset);
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,
diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
index ceb05b876597..b109a0810a2c 100644
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -632,20 +632,18 @@ retry_private:
return ret;
}
-int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset)
+int __futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
+ struct hrtimer_sleeper *to, u32 bitset)
{
- struct hrtimer_sleeper timeout, *to;
- struct restart_block *restart;
- struct futex_hash_bucket *hb;
struct futex_q q = futex_q_init;
+ struct futex_hash_bucket *hb;
int ret;
if (!bitset)
return -EINVAL;
+
q.bitset = bitset;
- to = futex_setup_timer(abs_time, &timeout, flags,
- current->timer_slack_ns);
retry:
/*
* Prepare to wait on uaddr. On success, it holds hb->lock and q
@@ -653,18 +651,17 @@ retry:
*/
ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
if (ret)
- goto out;
+ return ret;
/* futex_queue and wait for wakeup, timeout, or a signal. */
futex_wait_queue(hb, &q, to);
/* If we were woken (and unqueued), we succeeded, whatever. */
- ret = 0;
if (!futex_unqueue(&q))
- goto out;
- ret = -ETIMEDOUT;
+ return 0;
+
if (to && !to->task)
- goto out;
+ return -ETIMEDOUT;
/*
* We expect signal_pending(current), but we might be the
@@ -673,24 +670,38 @@ retry:
if (!signal_pending(current))
goto retry;
- ret = -ERESTARTSYS;
- if (!abs_time)
- goto out;
+ return -ERESTARTSYS;
+}
- restart = &current->restart_block;
- restart->futex.uaddr = uaddr;
- restart->futex.val = val;
- restart->futex.time = *abs_time;
- restart->futex.bitset = bitset;
- restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;
+int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time, u32 bitset)
+{
+ struct hrtimer_sleeper timeout, *to;
+ struct restart_block *restart;
+ int ret;
+
+ to = futex_setup_timer(abs_time, &timeout, flags,
+ current->timer_slack_ns);
+
+ ret = __futex_wait(uaddr, flags, val, to, bitset);
+
+ /* No timeout, nothing to clean up. */
+ if (!to)
+ return ret;
+
+ hrtimer_cancel(&to->timer);
+ destroy_hrtimer_on_stack(&to->timer);
- ret = set_restart_fn(restart, futex_wait_restart);
+ if (ret == -ERESTARTSYS) {
+ restart = &current->restart_block;
+ restart->futex.uaddr = uaddr;
+ restart->futex.val = val;
+ restart->futex.time = *abs_time;
+ restart->futex.bitset = bitset;
+ restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;
-out:
- if (to) {
- hrtimer_cancel(&to->timer);
- destroy_hrtimer_on_stack(&to->timer);
+ return set_restart_fn(restart, futex_wait_restart);
}
+
return ret;
}