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* futex: make the vectored futex operations availableJens Axboe2023-09-291-0/+5
| | | | | | | | | Rename unqueue_multiple() as futex_unqueue_multiple(), and make both that and futex_wait_multiple_setup() available for external users. This is in preparation for wiring up vectored waits in io_uring. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* futex: make futex_parse_waitv() available as a helperJens Axboe2023-09-291-0/+5
| | | | | | | | | To make it more generically useful, augment it with allowing the caller to pass in the wake handler and wake data. Convert the futex_waitv() syscall, passing in the default handlers. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* futex: add wake_data to struct futex_qJens Axboe2023-09-291-0/+2
| | | | | | | | | With handling multiple futex_q for waitv, we cannot easily go from the futex_q to data related to that request or queue. Add a wake_data argument that belongs to the wake handler assigned. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* futex: abstract out a __futex_wake_mark() helperJens Axboe2023-09-291-0/+1
| | | | | | | | | | Move the unqueue and lock_ptr clear into a helper that futex_wake_mark() calls. Add it to the public functions as well, in preparation for using it outside the core futex code. Suggested-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* futex: factor out the futex wake handlingJens Axboe2023-09-291-0/+5
| | | | | | | | | | | | | | | | | | | In preparation for having another waker that isn't futex_wake_mark(), add a wake handler in futex_q. No extra data is associated with the handler outside of struct futex_q itself. futex_wake_mark() is defined as the standard wakeup helper, now set through futex_q_init like other defaults. Normal sync futex waiting relies on wake_q holding tasks that should be woken up. This is what futex_wake_mark() does, it'll unqueue the futex and add the associated task to the wake queue. For async usage of futex waiting, rather than having tasks sleeping on the futex, we'll need to deal with a futex wake differently. For the planned io_uring case, that means posting a completion event for the task in question. Having a definable wake handler can help support that use case. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* futex: move FUTEX2_VALID_MASK to futex.hJens Axboe2023-09-291-0/+2
| | | | | | | | We need this for validating the futex2 flags outside of the normal futex syscalls. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* futex: Add flags2 argument to futex_requeue()peterz@infradead.org2023-09-211-2/+3
| | | | | | | | | | | In order to support mixed size requeue, add a second flags argument to the internal futex_requeue() function. No functional change intended. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230921105248.396780136@noisy.programming.kicks-ass.net
* futex: Propagate flags into get_futex_key()peterz@infradead.org2023-09-211-1/+1
| | | | | | | | | | | Instead of only passing FLAGS_SHARED as a boolean, pass down flags as a whole. No functional change intended. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230921105248.282857501@noisy.programming.kicks-ass.net
* futex: Add sys_futex_wait()peterz@infradead.org2023-09-211-0/+3
| | | | | | | | | | | | | | | 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
* futex: FLAGS_STRICTpeterz@infradead.org2023-09-211-10/+11
| | | | | | | | | | | | | | | | | The current semantics for futex_wake() are a bit loose, specifically asking for 0 futexes to be woken actually gets you 1. Adding a !nr check to sys_futex_wake() makes that it would return 0 for unaligned futex words, because that check comes in the shared futex_wake() function. Adding the !nr check there, would affect the legacy sys_futex() semantics. Hence frob a flag :-( Suggested-by: André Almeida <andrealmeid@igalia.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230921105248.048643656@noisy.programming.kicks-ass.net
* futex: Validate futex value against futex sizepeterz@infradead.org2023-09-211-0/+10
| | | | | | | | | | | | Ensure the futex value fits in the given futex size. Since this adds a constraint to an existing syscall, it might possibly change behaviour. Currently the value would be truncated to a u32 and any high bits would get silently lost. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230921105247.828934099@noisy.programming.kicks-ass.net
* futex: Flag conversionpeterz@infradead.org2023-09-211-3/+60
| | | | | | | | | | | | | | | | Futex has 3 sets of flags: - legacy futex op bits - futex2 flags - internal flags Add a few helpers to convert from the API flags into the internal flags. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: André Almeida <andrealmeid@igalia.com> Link: https://lore.kernel.org/r/20230921105247.722140574@noisy.programming.kicks-ass.net
* futex: add missing rtmutex.h includeChristian König2022-04-071-0/+1
| | | | | | | | | | This isn't included here any more since the removal of ww_mutex.h from seqlock.h which causes a build break. Signed-off-by: Christian König <christian.koenig@amd.com> Acked-by: Shashank Sharma <shashank.sharma@amd.com> Fixes: e84815cbbc76 ("seqlock: drop seqcount_ww_mutex_t") Link: https://patchwork.freedesktop.org/patch/msgid/20220407114619.961750-1-christian.koenig@amd.com
* futex: Remove futex_cmpxchg detectionArnd Bergmann2021-11-251-6/+0
| | | | | | | | | | | | | | Now that all architectures have a working futex implementation in any configuration, remove the runtime detection code. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Acked-by: Vineet Gupta <vgupta@kernel.org> Acked-by: Max Filippov <jcmvbkbc@gmail.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Link: https://lore.kernel.org/r/20211026100432.1730393-2-arnd@kernel.org
* futex: Fix PREEMPT_RT buildPeter Zijlstra2021-10-191-0/+4
| | | | | | | | Mike reported that rcuwait went walk-about and is causing failures on the PREEMPT_RT builds, restore it. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
* futex: Implement sys_futex_waitv()André Almeida2021-10-071-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add support to wait on multiple futexes. This is the interface implemented by this syscall: futex_waitv(struct futex_waitv *waiters, unsigned int nr_futexes, unsigned int flags, struct timespec *timeout, clockid_t clockid) struct futex_waitv { __u64 val; __u64 uaddr; __u32 flags; __u32 __reserved; }; Given an array of struct futex_waitv, wait on each uaddr. The thread wakes if a futex_wake() is performed at any uaddr. The syscall returns immediately if any waiter has *uaddr != val. *timeout is an optional absolute timeout value for the operation. This syscall supports only 64bit sized timeout structs. The flags argument of the syscall should be empty, but it can be used for future extensions. Flags for shared futexes, sizes, etc. should be used on the individual flags of each waiter. __reserved is used for explicit padding and should be 0, but it might be used for future extensions. If the userspace uses 32-bit pointers, it should make sure to explicitly cast it when assigning to waitv::uaddr. Returns the array index of one of the woken futexes. There’s no given information of how many were woken, or any particular attribute of it (if it’s the first woken, if it is of the smaller index...). Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210923171111.300673-17-andrealmeid@collabora.com
* futex: Simplify double_lock_hb()Peter Zijlstra2021-10-071-8/+6
| | | | | | | | | | | | | | We need to make sure that all requeue operations take the hash bucket locks in the same order to avoid deadlock. Simplify the current double_lock_hb implementation by making sure hb1 is always the "smallest" bucket to avoid extra checks. [André: Add commit description] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: André Almeida <andrealmeid@collabora.com> Link: https://lore.kernel.org/r/20210923171111.300673-16-andrealmeid@collabora.com
* futex: Split out wait/wakePeter Zijlstra2021-10-071-0/+34
| | | | | | | | | | Move the wait/wake bits into their own file. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: André Almeida <andrealmeid@collabora.com> Link: https://lore.kernel.org/r/20210923171111.300673-15-andrealmeid@collabora.com
* futex: Split out requeuePeter Zijlstra2021-10-071-2/+75
| | | | | | | | | | Move all the requeue bits into their own file. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: André Almeida <andrealmeid@collabora.com> Link: https://lore.kernel.org/r/20210923171111.300673-14-andrealmeid@collabora.com
* futex: Split out PI futexPeter Zijlstra2021-10-071-0/+117
| | | | | | | | | | Move the PI futex implementation into it's own file. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: André Almeida <andrealmeid@collabora.com> Link: https://lore.kernel.org/r/20210923171111.300673-10-andrealmeid@collabora.com
* futex: Split out syscallsPeter Zijlstra2021-10-071-0/+58
Put the syscalls in their own little file. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: André Almeida <andrealmeid@collabora.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: André Almeida <andrealmeid@collabora.com> Link: https://lore.kernel.org/r/20210923171111.300673-3-andrealmeid@collabora.com
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