diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2025-04-16 18:29:13 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-05-03 12:02:08 +0200 |
| commit | 7c4f75a21f636486d2969d9b6680403ea8483539 (patch) | |
| tree | 7ba61bc8ba91244f8180bcd17e7f54679fe9e0aa /kernel/fork.c | |
| parent | 80367ad01d93ac781b0e1df246edaf006928002f (diff) | |
futex: Allow automatic allocation of process wide futex hash
Allocate a private futex hash with 16 slots if a task forks its first
thread.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250416162921.513656-14-bigeasy@linutronix.de
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 831dfec45054..1f5d8083eeb2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2164,6 +2164,13 @@ static void rv_task_fork(struct task_struct *p) #define rv_task_fork(p) do {} while (0) #endif +static bool need_futex_hash_allocate_default(u64 clone_flags) +{ + if ((clone_flags & (CLONE_THREAD | CLONE_VM)) != (CLONE_THREAD | CLONE_VM)) + return false; + return true; +} + /* * This creates a new process as a copy of the old one, * but does not actually start it yet. @@ -2545,6 +2552,21 @@ __latent_entropy struct task_struct *copy_process( goto bad_fork_cancel_cgroup; /* + * Allocate a default futex hash for the user process once the first + * thread spawns. + */ + if (need_futex_hash_allocate_default(clone_flags)) { + retval = futex_hash_allocate_default(); + if (retval) + goto bad_fork_core_free; + /* + * If we fail beyond this point we don't free the allocated + * futex hash map. We assume that another thread will be created + * and makes use of it. The hash map will be freed once the main + * thread terminates. + */ + } + /* * From this point on we must avoid any synchronous user-space * communication until we take the tasklist-lock. In particular, we do * not want user-space to be able to predict the process start-time by |