linux/kernel/locking/lockdep.c, branch v5.12

lockdep: Address clang -Wformat warning printing for %hd

2021-03-22T21:07:09Z

Clang doesn't like format strings that truncate a 32-bit value to something shorter: kernel/locking/lockdep.c:709:4: error: format specifies type 'short' but the argument has type 'int' [-Werror,-Wformat] In this case, the warning is a slightly questionable, as it could realize that both class->wait_type_outer and class->wait_type_inner are in fact 8-bit struct members, even though the result of the ?: operator becomes an 'int'. However, there is really no point in printing the number as a 16-bit 'short' rather than either an 8-bit or 32-bit number, so just change it to a normal %d. Fixes: de8f5e4f2dc1 ("lockdep: Introduce wait-type checks") Signed-off-by: Arnd Bergmann Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210322115531.3987555-1-arnd@kernel.org

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

2021-03-21T10:59:57Z

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

Merge branch 'linus' into locking/core, to pick up upstream fixes

2021-02-12T11:54:58Z

Signed-off-by: Ingo Molnar

locking/lockdep: Avoid unmatched unlock

2021-02-05T16:20:15Z

Commit f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions") overlooked that print_usage_bug() releases the graph_lock and called it without the graph lock held. Fixes: f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions") Reported-by: Dmitry Vyukov Signed-off-by: Peter Zijlstra (Intel) Acked-by: Waiman Long Link: https://lkml.kernel.org/r/YBfkuyIfB1+VRxXP@hirez.programming.kicks-ass.net

locking/lockdep: Exclude local_lock_t from IRQ inversions

2021-01-14T10:20:17Z

The purpose of local_lock_t is to abstract: preempt_disable() / local_bh_disable() / local_irq_disable(). These are the traditional means of gaining access to per-cpu data, but are fundamentally non-preemptible. local_lock_t provides a per-cpu lock, that on !PREEMPT_RT reduces to no-ops, just like regular spinlocks do on UP. This gives rise to: CPU0 CPU1 local_lock(B) spin_lock_irq(A) spin_lock(A) local_lock(B) Where lockdep then figures things will lock up; which would be true if B were any other kind of lock. However this is a false positive, no such deadlock actually exists. For !RT the above local_lock(B) is preempt_disable(), and there's obviously no deadlock; alternatively, CPU0's B != CPU1's B. For RT the argument is that since local_lock() nests inside spin_lock(), it cannot be used in hardirq context, and therefore CPU0 cannot in fact happen. Even though B is a real lock, it is a preemptible lock and any threaded-irq would simply schedule out and let the preempted task (which holds B) continue such that the task on CPU1 can make progress, after which the threaded-irq resumes and can finish. This means that we can never form an IRQ inversion on a local_lock dependency, so terminate the graph walk when looking for IRQ inversions when we encounter one. One consequence is that (for LOCKDEP_SMALL) when we look for redundant dependencies, A -> B is not redundant in the presence of A -> L -> B. Signed-off-by: Boqun Feng [peterz: Changelog] Signed-off-by: Peter Zijlstra (Intel)

locking/lockdep: Clean up check_redundant() a bit

2021-01-14T10:20:17Z

In preparation for adding an TRACE_IRQFLAGS dependent skip function to check_redundant(), move it below the TRACE_IRQFLAGS #ifdef. While there, provide a stub function to reduce #ifdef usage. Signed-off-by: Peter Zijlstra (Intel)

locking/lockdep: Add a skip() function to __bfs()

2021-01-14T10:20:17Z

Some __bfs() walks will have additional iteration constraints (beyond the path being strong). Provide an additional function to allow terminating graph walks. Signed-off-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel)

locking/lockdep: Mark local_lock_t

2021-01-14T10:20:17Z

The local_lock_t's are special, because they cannot form IRQ inversions, make sure we can tell them apart from the rest of the locks. Signed-off-by: Peter Zijlstra (Intel)

locking/lockdep: Avoid noinstr warning for DEBUG_LOCKDEP

2021-01-12T20:10:59Z

vmlinux.o: warning: objtool: lock_is_held_type()+0x60: call to check_flags.part.0() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210106144017.652218215@infradead.org

locking/lockdep: Cure noinstr fail

2021-01-12T20:10:59Z

When the compiler doesn't feel like inlining, it causes a noinstr fail: vmlinux.o: warning: objtool: lock_is_held_type()+0xb: call to lockdep_enabled() leaves .noinstr.text section Fixes: 4d004099a668 ("lockdep: Fix lockdep recursion") Reported-by: Randy Dunlap Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210106144017.592595176@infradead.org