user/sven/linux.git/kernel/locking/lockdep.c, branch v5.4.250

treewide: Remove uninitialized_var() usage

2023-06-09T08:29:01Z

commit 3f649ab728cda8038259d8f14492fe400fbab911 upstream. Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe # IB Acked-by: Kalle Valo # wireless drivers Reviewed-by: Chao Yu # erofs Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

locking/lockdep: Avoid RCU-induced noinstr fail

2021-11-17T08:48:28Z

[ Upstream commit ce0b9c805dd66d5e49fd53ec5415ae398f4c56e6 ] vmlinux.o: warning: objtool: look_up_lock_class()+0xc7: call to rcu_read_lock_any_held() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210624095148.311980536@infradead.org Signed-off-by: Sasha Levin

lockding/lockdep: Avoid to find wrong lock dep path in check_irq_usage()

2021-07-14T14:53:15Z

[ Upstream commit 7b1f8c6179769af6ffa055e1169610b51d71edd5 ] In the step #3 of check_irq_usage(), we seach backwards to find a lock whose usage conflicts the usage of @target_entry1 on safe/unsafe. However, we should only keep the irq-unsafe usage of @target_entry1 into consideration, because it could be a case where a lock is hardirq-unsafe but soft-safe, and in check_irq_usage() we find it because its hardirq-unsafe could result into a hardirq-safe-unsafe deadlock, but currently since we don't filter out the other usage bits, so we may find a lock dependency path softirq-unsafe -> softirq-safe, which in fact doesn't cause a deadlock. And this may cause misleading lockdep splats. Fix this by only keeping LOCKF_ENABLED_IRQ_ALL bits when we try the backwards search. Reported-by: Johannes Berg Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210618170110.3699115-4-boqun.feng@gmail.com Signed-off-by: Sasha Levin

locking/lockdep: Fix the dep path printing for backwards BFS

2021-07-14T14:53:15Z

[ Upstream commit 69c7a5fb2482636f525f016c8333fdb9111ecb9d ] We use the same code to print backwards lock dependency path as the forwards lock dependency path, and this could result into incorrect printing because for a backwards lock_list ->trace is not the call trace where the lock of ->class is acquired. Fix this by introducing a separate function on printing the backwards dependency path. Also add a few comments about the printing while we are at it. Reported-by: Johannes Berg Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210618170110.3699115-2-boqun.feng@gmail.com Signed-off-by: Sasha Levin

lockdep: Add a missing initialization hint to the "INFO: Trying to register non-static key" message

2021-04-21T10:56:13Z

[ Upstream commit 3a85969e9d912d5dd85362ee37b5f81266e00e77 ] Since this message is printed when dynamically allocated spinlocks (e.g. kzalloc()) are used without initialization (e.g. spin_lock_init()), suggest to developers to check whether initialization functions for objects were called, before making developers wonder what annotation is missing. [ mingo: Minor tweaks to the message. ] Signed-off-by: Tetsuo Handa Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210321064913.4619-1-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin

locking/lockdep: Decrement IRQ context counters when removing lock chain

2020-10-01T11:17:33Z

[ Upstream commit b3b9c187dc2544923a601733a85352b9ddaba9b3 ] There are currently three counters to track the IRQ context of a lock chain - nr_hardirq_chains, nr_softirq_chains and nr_process_chains. They are incremented when a new lock chain is added, but they are not decremented when a lock chain is removed. That causes some of the statistic counts reported by /proc/lockdep_stats to be incorrect. IRQ Fix that by decrementing the right counter when a lock chain is removed. Since inc_chains() no longer accesses hardirq_context and softirq_context directly, it is moved out from the CONFIG_TRACE_IRQFLAGS conditional compilation block. Fixes: a0b0fd53e1e6 ("locking/lockdep: Free lock classes that are no longer in use") Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lkml.kernel.org/r/20200206152408.24165-2-longman@redhat.com Signed-off-by: Sasha Levin

locking/lockdep: Avoid recursion in lockdep_count_{for,back}ward_deps()

2020-04-17T08:50:05Z

[ Upstream commit 25016bd7f4caf5fc983bbab7403d08e64cba3004 ] Qian Cai reported a bug when PROVE_RCU_LIST=y, and read on /proc/lockdep triggered a warning: [ ] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) ... [ ] Call Trace: [ ] lock_is_held_type+0x5d/0x150 [ ] ? rcu_lockdep_current_cpu_online+0x64/0x80 [ ] rcu_read_lock_any_held+0xac/0x100 [ ] ? rcu_read_lock_held+0xc0/0xc0 [ ] ? __slab_free+0x421/0x540 [ ] ? kasan_kmalloc+0x9/0x10 [ ] ? __kmalloc_node+0x1d7/0x320 [ ] ? kvmalloc_node+0x6f/0x80 [ ] __bfs+0x28a/0x3c0 [ ] ? class_equal+0x30/0x30 [ ] lockdep_count_forward_deps+0x11a/0x1a0 The warning got triggered because lockdep_count_forward_deps() call __bfs() without current->lockdep_recursion being set, as a result a lockdep internal function (__bfs()) is checked by lockdep, which is unexpected, and the inconsistency between the irq-off state and the state traced by lockdep caused the warning. Apart from this warning, lockdep internal functions like __bfs() should always be protected by current->lockdep_recursion to avoid potential deadlocks and data inconsistency, therefore add the current->lockdep_recursion on-and-off section to protect __bfs() in both lockdep_count_forward_deps() and lockdep_count_backward_deps() Reported-by: Qian Cai Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200312151258.128036-1-boqun.feng@gmail.com Signed-off-by: Sasha Levin

locking/lockdep: Fix buffer overrun problem in stack_trace[]

2020-01-23T07:22:39Z

commit d91f3057263ceb691ef527e71b41a56b17f6c869 upstream. If the lockdep code is really running out of the stack_trace entries, it is likely that buffer overrun can happen and the data immediately after stack_trace[] will be corrupted. If there is less than LOCK_TRACE_SIZE_IN_LONGS entries left before the call to save_trace(), the max_entries computation will leave it with a very large positive number because of its unsigned nature. The subsequent call to stack_trace_save() will then corrupt the data after stack_trace[]. Fix that by changing max_entries to a signed integer and check for negative value before calling stack_trace_save(). Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Bart Van Assche Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 12593b7467f9 ("locking/lockdep: Reduce space occupied by stack traces") Link: https://lkml.kernel.org/r/20191220135128.14876-1-longman@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-09-16T23:49:55Z

Pull locking updates from Ingo Molnar: - improve rwsem scalability - add uninitialized rwsem debugging check - reduce lockdep's stacktrace memory usage and add diagnostics - misc cleanups, code consolidation and constification * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: mutex: Fix up mutex_waiter usage locking/mutex: Use mutex flags macro instead of hard code locking/mutex: Make __mutex_owner static to mutex.c locking/qspinlock,x86: Clarify virt_spin_lock_key locking/rwsem: Check for operations on an uninitialized rwsem locking/rwsem: Make handoff writer optimistically spin on owner locking/lockdep: Report more stack trace statistics locking/lockdep: Reduce space occupied by stack traces stacktrace: Constify 'entries' arguments locking/lockdep: Make it clear that what lock_class::key points at is not modified

lockdep: Make print_lock() address visible

2019-08-01T21:05:51Z

Security is a wonderful thing, but so is the ability to debug based on lockdep warnings. This commit therefore makes lockdep lock addresses visible in the clear. Signed-off-by: Paul E. McKenney