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Linux 6.11: avoid passing "end" sentinel to register_sysctl()

Browse Source 
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #16400
This commit is contained in:
Rob Norris 2024-07-31 21:39:31 +10:00 committed by Tony Hutter
parent 8156099cf2
commit 8479a45abe
3 changed files with 66 additions and 3 deletions
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26
config/kernel-register_sysctl_table.m4
View File

@ -26,6 +26,32 @@ AC_DEFUN([ZFS_AC_KERNEL_REGISTER_SYSCTL_TABLE], [
])
])
dnl #
dnl # Linux 6.11 register_sysctl() enforces that sysctl tables no longer
dnl # supply a sentinel end-of-table element. 6.6 introduces
dnl # register_sysctl_sz() to enable callers to choose, so we use it if
dnl # available for backward compatibility.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_REGISTER_SYSCTL_SZ], [
ZFS_LINUX_TEST_SRC([has_register_sysctl_sz], [
#include <linux/sysctl.h>
],[
struct ctl_table test_table[] __attribute__((unused)) = {0};
register_sysctl_sz("", test_table, 0);
])
])
AC_DEFUN([ZFS_AC_KERNEL_REGISTER_SYSCTL_SZ], [
AC_MSG_CHECKING([whether register_sysctl_sz exists])
ZFS_LINUX_TEST_RESULT([has_register_sysctl_sz], [
AC_MSG_RESULT([yes])
AC_DEFINE(HAVE_REGISTER_SYSCTL_SZ, 1,
[register_sysctl_sz exists])
],[
AC_MSG_RESULT([no])
])
])
dnl #
dnl # Linux 6.11 makes const the ctl_table arg of proc_handler
dnl #

2
config/kernel.m4
View File

@ -166,6 +166,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
ZFS_AC_KERNEL_SRC_WRITEPAGE_T
ZFS_AC_KERNEL_SRC_RECLAIMED
ZFS_AC_KERNEL_SRC_REGISTER_SYSCTL_TABLE
ZFS_AC_KERNEL_SRC_REGISTER_SYSCTL_SZ
ZFS_AC_KERNEL_SRC_PROC_HANDLER_CTL_TABLE_CONST
ZFS_AC_KERNEL_SRC_COPY_SPLICE_READ
ZFS_AC_KERNEL_SRC_SYNC_BDEV
@ -319,6 +320,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
ZFS_AC_KERNEL_WRITEPAGE_T
ZFS_AC_KERNEL_RECLAIMED
ZFS_AC_KERNEL_REGISTER_SYSCTL_TABLE
ZFS_AC_KERNEL_REGISTER_SYSCTL_SZ
ZFS_AC_KERNEL_PROC_HANDLER_CTL_TABLE_CONST
ZFS_AC_KERNEL_COPY_SPLICE_READ
ZFS_AC_KERNEL_SYNC_BDEV

41
module/os/linux/spl/spl-proc.c
View File

@ -22,6 +22,9 @@
*
* Solaris Porting Layer (SPL) Proc Implementation.
*/
/*
* Copyright (c) 2024, Rob Norris <robn@despairlabs.com>
*/
#include <sys/systeminfo.h>
#include <sys/kstat.h>
@ -694,6 +697,37 @@ static void spl_proc_cleanup(void)
}
}
#ifndef HAVE_REGISTER_SYSCTL_TABLE
/*
* Traditionally, struct ctl_table arrays have been terminated by an "empty"
* sentinel element (specifically, one with .procname == NULL).
*
* Linux 6.6 began migrating away from this, adding register_sysctl_sz() so
* that callers could provide the size directly, and redefining
* register_sysctl() to just call register_sysctl_sz() with the array size. It
* retained support for the terminating element so that existing callers would
* continue to work.
*
* Linux 6.11 removed support for the terminating element, instead interpreting
* it as a real malformed element, and rejecting it.
*
* In order to continue support older kernels, we retain the terminating
* sentinel element for our sysctl tables, but instead detect availability of
* register_sysctl_sz(). If it exists, we pass it the array size -1, stopping
* the kernel from trying to process the terminator. For pre-6.6 kernels that
* don't have register_sysctl_sz(), we just use register_sysctl(), which can
* handle the terminating element as it always has.
*/
#ifdef HAVE_REGISTER_SYSCTL_SZ
#define spl_proc_register_sysctl(p, t) \
register_sysctl_sz(p, t, ARRAY_SIZE(t)-1)
#else
#define spl_proc_register_sysctl(p, t) \
register_sysctl(p, t)
#endif
#endif
int
spl_proc_init(void)
{
@ -704,16 +738,17 @@ spl_proc_init(void)
if (spl_header == NULL)
return (-EUNATCH);
#else
spl_header = register_sysctl("kernel/spl", spl_table);
spl_header = spl_proc_register_sysctl("kernel/spl", spl_table);
if (spl_header == NULL)
return (-EUNATCH);
spl_kmem = register_sysctl("kernel/spl/kmem", spl_kmem_table);
spl_kmem = spl_proc_register_sysctl("kernel/spl/kmem", spl_kmem_table);
if (spl_kmem == NULL) {
rc = -EUNATCH;
goto out;
}
spl_kstat = register_sysctl("kernel/spl/kstat", spl_kstat_table);
spl_kstat = spl_proc_register_sysctl("kernel/spl/kstat",
spl_kstat_table);
if (spl_kstat == NULL) {
rc = -EUNATCH;
goto out;