selftests/bpf: Test rhtab kptr cancellation semanticsgrafted

Resizable hash-map updates and deletions must not perform full special-field
destruction in their caller context. In particular, a referenced kptr must
remain attached to the allocation until the memory allocator destructor can
release it safely.

Add separate coverage for both affected paths. The update test stores a task
kptr, replaces the ordinary value bytes with BPF_EXIST, and verifies that the
kptr survived. The delete test removes an element and exchanges its kptr
through the still-valid map-value pointer before the allocation is reclaimed.

Both cases observe a NULL kptr when rhtab uses bpf_obj_free_fields(). They
recover and release the reference after rhtab switches to cancellation
semantics.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
[ kkd: Split update and delete coverage and rewrote the commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 76 insertions, 0 deletions

diff --git a/scripts/checkversion.pl b/scripts/checkversion.pl
new file mode 100755
index 000000000..94cd49eff
--- /dev/null
+++ b/scripts/checkversion.pl
@@ -0,0 +1,76 @@
+#! /usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+#
+# checkversion finds uses of all macros in <linux/version.h>
+# where the source files do not #include <linux/version.h>; or cases
+# of including <linux/version.h> where it is not needed.
+# Copyright (C) 2003, Randy Dunlap <rdunlap@infradead.org>
+
+use strict;
+
+$| = 1;
+
+my $debugging;
+
+foreach my $file (@ARGV) {
+    next if $file =~ "include/generated/uapi/linux/version\.h";
+    next if $file =~ "usr/include/linux/version\.h";
+    # Open this file.
+    open( my $f, '<', $file )
+      or die "Can't open $file: $!\n";
+
+    # Initialize variables.
+    my ($fInComment, $fInString, $fUseVersion);
+    my $iLinuxVersion = 0;
+
+    while (<$f>) {
+	# Strip comments.
+	$fInComment && (s+^.*?\*/+ +o ? ($fInComment = 0) : next);
+	m+/\*+o && (s+/\*.*?\*/+ +go, (s+/\*.*$+ +o && ($fInComment = 1)));
+
+	# Pick up definitions.
+	if ( m/^\s*#/o ) {
+	    $iLinuxVersion      = $. if m/^\s*#\s*include\s*"linux\/version\.h"/o;
+	}
+
+	# Strip strings.
+	$fInString && (s+^.*?"+ +o ? ($fInString = 0) : next);
+	m+"+o && (s+".*?"+ +go, (s+".*$+ +o && ($fInString = 1)));
+
+	# Pick up definitions.
+	if ( m/^\s*#/o ) {
+	    $iLinuxVersion      = $. if m/^\s*#\s*include\s*<linux\/version\.h>/o;
+	}
+
+	# Look for uses: LINUX_VERSION_CODE, KERNEL_VERSION,
+	# LINUX_VERSION_MAJOR, LINUX_VERSION_PATCHLEVEL, LINUX_VERSION_SUBLEVEL
+	if (($_ =~ /LINUX_VERSION_CODE/) || ($_ =~ /\WKERNEL_VERSION/) ||
+	    ($_ =~ /LINUX_VERSION_MAJOR/) || ($_ =~ /LINUX_VERSION_PATCHLEVEL/) ||
+	    ($_ =~ /LINUX_VERSION_SUBLEVEL/)) {
+	    $fUseVersion = 1;
+            last if $iLinuxVersion;
+        }
+    }
+
+    # Report used version IDs without include?
+    if ($fUseVersion && ! $iLinuxVersion) {
+	print "$file: $.: need linux/version.h\n";
+    }
+
+    # Report superfluous includes.
+    if ($iLinuxVersion && ! $fUseVersion) {
+	print "$file: $iLinuxVersion linux/version.h not needed.\n";
+    }
+
+    # debug: report OK results:
+    if ($debugging) {
+        if ($iLinuxVersion && $fUseVersion) {
+	    print "$file: version use is OK ($iLinuxVersion)\n";
+        }
+        if (! $iLinuxVersion && ! $fUseVersion) {
+	    print "$file: version use is OK (none)\n";
+        }
+    }
+
+    close($f);
+}