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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Alejandro Colomar <alx@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-man@vger.kernel.org,
	"André Almeida" <andrealmeid@igalia.com>,
	"Darren Hart" <dvhart@infradead.org>,
	"Davidlohr Bueso" <dave@stgolabs.net>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Juri Lelli" <juri.lelli@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Valentin Schneider" <vschneid@redhat.com>,
	"Waiman Long" <longman@redhat.com>
Subject: [PATCH v6] man/man2/prctl.2, PR_FUTEX_HASH_SET_SLOTS.2const: Document PR_FUTEX_HASH_SET_SLOTS
Date: Fri, 22 Aug 2025 16:32:24 +0200	[thread overview]
Message-ID: <20250822143224.1fKxH5mb@linutronix.de> (raw)
In-Reply-To: <wygherozbi27pom3xgfcev6pweliuap44cli2vuqhyaqth3dkf@vrkh2iu75tyn>

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
v5…v6:
  - hash_size -> size
  - hash_flags -> flags

 man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const | 67 ++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const

diff --git a/man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const b/man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const
new file mode 100644
index 0000000000000..1605c18c6985b
--- /dev/null
+++ b/man/man2const/PR_FUTEX_HASH_SET_SLOTS.2const
@@ -0,0 +1,67 @@
+.\" Copyright, the authors of the Linux man-pages project
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH PR_FUTEX_HASH_SET_SLOTS 2const (date) "Linux man-pages (unreleased)"
+.SH NAME
+PR_FUTEX_HASH_SET_SLOTS
+\-
+set the size of the private hash
+.SH LIBRARY
+Standard C library
+.RI ( libc ,\~ \-lc )
+.SH SYNOPSIS
+.nf
+.BR "#include <linux/prctl.h>" "  /* Definition of " PR_* " constants */"
+.B #include <sys/prctl.h>
+.P
+.B int prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS,
+.BI "          unsigned long " size ", unsigned long " flags ");
+.fi
+.SH DESCRIPTION
+Set the number of slots to use for the private hash.
+.TP
+.I size
+Specify the size of private hash to allocate.
+.RS
+.TP
+.I 0
+Use the global hash.
+This is the behaviour used before 6.17.
+.TP
+.I >0
+Specify the number of slots to allocate.
+The value must be power of two, and the lowest possible value is 2.
+The upper limit depends on the available memory in the system.
+Each slot requires 64 bytes of memory.
+Kernels compiled with
+.I CONFIG_PROVE_LOCKING
+will consume more than that.
+.RE
+.TP
+.I flags
+.RS
+The argument must be 0.
+.SH RETURN VALUE
+On success,
+0 is returned.
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+An argument is invalid.
+.TP
+.B ENOMEM
+Failed to allocate memory.
+.TP
+.B EBUSY
+The global hash is in use and can not be changed.
+.SH STANDARDS
+Linux.
+.SH HISTORY
+Linux 6.17.
+.SH SEE ALSO
+.BR prctl (2),
+.BR PR_FUTEX_HASH (2const)
-- 
2.50.1


  reply	other threads:[~2025-08-22 14:32 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-19  7:17 [PATCH v5 0/3] Add documentation for PR_FUTEX_HASH Sebastian Andrzej Siewior
2025-08-19  7:17 ` [PATCH v5 1/3] man/man2const/PR_FUTEX_HASH.2const: Update as of Linux v6.17-rc2 Sebastian Andrzej Siewior
2025-08-19 11:03   ` Alejandro Colomar
2025-08-19  7:17 ` [PATCH v5 2/3] man/man2/prctl.2, PR_FUTEX_HASH_SET_SLOTS.2const: Document PR_FUTEX_HASH_SET_SLOTS Sebastian Andrzej Siewior
2025-08-19 11:02   ` Alejandro Colomar
2025-08-19 11:19     ` Alejandro Colomar
2025-08-21 14:08       ` Sebastian Andrzej Siewior
2025-08-21 19:14         ` Alejandro Colomar
2025-08-22 14:32           ` Sebastian Andrzej Siewior [this message]
2025-08-19  7:17 ` [PATCH v5 3/3] man/man2/prctl.2, PR_FUTEX_HASH_GET_SLOTS.2const: Document PR_FUTEX_HASH_GET_SLOTS Sebastian Andrzej Siewior
2025-08-19 11:07   ` Alejandro Colomar

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