linux-stable/include/linux/threads.h
Jann Horn 9c40365a65 threads: Update PID limit comment according to futex UAPI change
The futex UAPI changed back in commit 76b81e2b0e ("[PATCH] lightweight
robust futexes updates 2"), which landed in v2.6.17: FUTEX_TID_MASK is now
0x3fffffff instead of 0x1fffffff. Update the corresponding comment in
include/linux/threads.h.

Documentation mentions that only the lower 29 bits are available for TID
storage, but as the UAPI header released the bit already via
FUTEX_TID_MASK, this is moot as well. Fix it up.

[ tglx: Fixed up documentation ]

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200302112939.8068-1-jannh@google.com
2020-03-21 17:48:13 +01:00

46 lines
1.3 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_THREADS_H
#define _LINUX_THREADS_H
/*
* The default limit for the nr of threads is now in
* /proc/sys/kernel/threads-max.
*/
/*
* Maximum supported processors. Setting this smaller saves quite a
* bit of memory. Use nr_cpu_ids instead of this except for static bitmaps.
*/
#ifndef CONFIG_NR_CPUS
/* FIXME: This should be fixed in the arch's Kconfig */
#define CONFIG_NR_CPUS 1
#endif
/* Places which use this should consider cpumask_var_t. */
#define NR_CPUS CONFIG_NR_CPUS
#define MIN_THREADS_LEFT_FOR_ROOT 4
/*
* This controls the default maximum pid allocated to a process
*/
#define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)
/*
* A maximum of 4 million PIDs should be enough for a while.
* [NOTE: PID/TIDs are limited to 2^30 ~= 1 billion, see FUTEX_TID_MASK.]
*/
#define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
(sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
/*
* Define a minimum number of pids per cpu. Heuristically based
* on original pid max of 32k for 32 cpus. Also, increase the
* minimum settable value for pid_max on the running system based
* on similar defaults. See kernel/pid.c:pidmap_init() for details.
*/
#define PIDS_PER_CPU_DEFAULT 1024
#define PIDS_PER_CPU_MIN 8
#endif