'\" t
.\"     Title: ipcctl_pre_down_nolock
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: June 2017
.\"    Manual: Kernel IPC facilities
.\"    Source: Kernel Hackers Manual 4.11.3
.\"  Language: English
.\"
.TH "IPCCTL_PRE_DOWN_NOLO" "9" "June 2017" "Kernel Hackers Manual 4\&.11\&" "Kernel IPC facilities"
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.SH "NAME"
ipcctl_pre_down_nolock \- retrieve an ipc and check permissions for some IPC_XXX cmd
.SH "SYNOPSIS"
.HP \w'struct\ kern_ipc_perm\ *\ ipcctl_pre_down_nolock('u
.BI "struct kern_ipc_perm * ipcctl_pre_down_nolock(struct\ ipc_namespace\ *\ " "ns" ", struct\ ipc_ids\ *\ " "ids" ", int\ " "id" ", int\ " "cmd" ", struct\ ipc64_perm\ *\ " "perm" ", int\ " "extra_perm" ");"
.SH "ARGUMENTS"
.PP
\fIstruct ipc_namespace * ns\fR
.RS 4
ipc namespace
.RE
.PP
\fIstruct ipc_ids * ids\fR
.RS 4
the table of ids where to look for the ipc
.RE
.PP
\fIint id\fR
.RS 4
the id of the ipc to retrieve
.RE
.PP
\fIint cmd\fR
.RS 4
the cmd to check
.RE
.PP
\fIstruct ipc64_perm * perm\fR
.RS 4
the permission to set
.RE
.PP
\fIint extra_perm\fR
.RS 4
one extra permission parameter used by msq
.RE
.SH "DESCRIPTION"
.PP
This function does some common audit and permissions check for some IPC_XXX cmd and is called from semctl_down, shmctl_down and msgctl_down\&. It must be called without any lock held and \- retrieves the ipc with the given id in the given table\&. \- performs some audit and permission check, depending on the given cmd \- returns a pointer to the ipc object or otherwise, the corresponding error\&.
.PP
Call holding the both the rwsem and the rcu read lock\&.
.SH "COPYRIGHT"
.br