tools/lib/lockdep: drop liblockdep

TL;DR: While a tool like liblockdep is useful, it probably doesn't
belong within the kernel tree.

liblockdep attempts to reuse kernel code both directly (by directly
building the kernel's lockdep code) as well as indirectly (by using
sanitized headers). This makes liblockdep an integral part of the
kernel.

It also makes liblockdep quite unique: while other userspace code might
use sanitized headers, it generally doesn't attempt to use kernel code
directly which means that changes on the kernel side of things don't
affect (and break) it directly.

All our workflows and tooling around liblockdep don't support this
uniqueness. Changes that go into the kernel code aren't validated to not
break in-tree userspace code.

liblockdep ended up being very fragile, breaking over and over, to the
point that living in the same tree as the lockdep code lost most of it's
value.

liblockdep should continue living in an external tree, syncing with
the kernel often, in a controllable way.

Signed-off-by: Sasha Levin <sashal@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 29 deletions

diff --git a/tools/lib/lockdep/common.c b/tools/lib/lockdep/common.c
deleted file mode 100644
index 5c3b58cce8a9..000000000000
--- a/tools/lib/lockdep/common.c
+++ /dev/null
@@ -1,29 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <stddef.h>
-#include <stdbool.h>
-#include <linux/compiler.h>
-#include <linux/lockdep.h>
-#include <unistd.h>
-#include <sys/syscall.h>
-
-static __thread struct task_struct current_obj;
-
-/* lockdep wants these */
-bool debug_locks = true;
-bool debug_locks_silent;
-
-__attribute__((destructor)) static void liblockdep_exit(void)
-{
-	debug_check_no_locks_held();
-}
-
-struct task_struct *__curr(void)
-{
-	if (current_obj.pid == 0) {
-		/* Makes lockdep output pretty */
-		prctl(PR_GET_NAME, current_obj.comm);
-		current_obj.pid = syscall(__NR_gettid);
-	}
-
-	return &current_obj;
-}