linux/kernel/futex/syscalls.c, branch v6.17

futex: make futex_parse_waitv() available as a helper

2023-09-29T08:37:05Z

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) Signed-off-by: Jens Axboe

futex: move FUTEX2_VALID_MASK to futex.h

2023-09-29T08:36:16Z

We need this for validating the futex2 flags outside of the normal futex syscalls. Acked-by: Peter Zijlstra (Intel) Signed-off-by: Jens Axboe

futex: Add sys_futex_requeue()

2023-09-21T17:22:10Z

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) Reviewed-by: Thomas Gleixner Acked-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20230921105248.511860556@noisy.programming.kicks-ass.net

futex: Add flags2 argument to futex_requeue()

2023-09-21T17:22:09Z

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) Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230921105248.396780136@noisy.programming.kicks-ass.net

futex: Add sys_futex_wait()

2023-09-21T17:22:08Z

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) Reviewed-by: Thomas Gleixner Acked-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20230921105248.164324363@noisy.programming.kicks-ass.net

futex: FLAGS_STRICT

2023-09-21T17:22:07Z

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 Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230921105248.048643656@noisy.programming.kicks-ass.net

futex: Add sys_futex_wake()

2023-09-21T17:22:07Z

To complement sys_futex_waitv() add sys_futex_wake(). This syscall implements what was previously known as FUTEX_WAKE_BITSET except it uses 'unsigned long' for the bitmask and takes FUTEX2 flags. The 'unsigned long' allows FUTEX2_SIZE_U64 on 64bit platforms. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner Acked-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20230921105247.936205525@noisy.programming.kicks-ass.net

futex: Validate futex value against futex size

2023-09-21T17:22:06Z

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) Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230921105247.828934099@noisy.programming.kicks-ass.net

futex: Flag conversion

2023-09-21T17:22:05Z

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) Reviewed-by: Thomas Gleixner Reviewed-by: André Almeida Link: https://lore.kernel.org/r/20230921105247.722140574@noisy.programming.kicks-ass.net

futex: Extend the FUTEX2 flags

2023-09-21T17:22:05Z

Add the definition for the missing but always intended extra sizes, and add a NUMA flag for the planned numa extention. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner Reviewed-by: André Almeida Link: https://lore.kernel.org/r/20230921105247.617057368@noisy.programming.kicks-ass.net