[PATCH] docs: sysctl/kernel: document ngroups_max

[Stephen Kitt <steve@sk2.org>]

This is a read-only export of NGROUPS_MAX, so this patch also changes
the declarations in kernel/sysctl.c to const.

Signed-off-by: Stephen Kitt <steve@sk2.org>
---
 Documentation/admin-guide/sysctl/kernel.rst | 9 +++++++++
 kernel/sysctl.c                             | 4 ++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 0d427fd10941..5f12ee07665c 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -459,6 +459,15 @@ Notes:
      successful IPC object allocation. If an IPC object allocation syscall
      fails, it is undefined if the value remains unmodified or is reset to -1.
 
+
+ngroups_max
+===========
+
+Maximum number of supplementary groups, _i.e._ the maximum size which
+``setgroups`` will accept. Exports ``NGROUPS_MAX`` from the kernel.
+
+
+
 nmi_watchdog
 ============
 
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8a176d8727a3..2ba9f449d273 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -146,7 +146,7 @@ static unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
 static int maxolduid = 65535;
 static int minolduid;
 
-static int ngroups_max = NGROUPS_MAX;
+static const int ngroups_max = NGROUPS_MAX;
 static const int cap_last_cap = CAP_LAST_CAP;
 
 /*
@@ -883,7 +883,7 @@ static struct ctl_table kern_table[] = {
 #endif
 	{
 		.procname	= "ngroups_max",
-		.data		= &ngroups_max,
+		.data		= (void *)&ngroups_max,
 		.maxlen		= sizeof (int),
 		.mode		= 0444,
 		.proc_handler	= proc_dointvec,

base-commit: 1ae7efb388540adc1653a51a3bc3b2c9cef5ec1a
-- 
2.20.1