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Groups > linux.kernel > #1570123
| From | "J. R. Okajima" <hooanon05g@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Q: lockdep_assert_held_read() after downgrade_write() |
| Date | 2017-01-30 22:30 +0100 |
| Message-ID | <t5rGq-Ac-35@gated-at.bofh.it> (permalink) |
| Organization | linux.* mail to news gateway |
Peter Zijlstra,
May I ask you a question?
v4.10-rc1 got a commit
f831948 2016-11-30 locking/lockdep: Provide a type check for lock_is_held
I've tested a little and lockdep splat a stack trace.
{
DECLARE_RWSEM(rw);
static struct lock_class_key key;
lockdep_set_class(&rw, &key);
down_read(&rw);
lockdep_assert_held_read(&rw);
up_read(&rw);
down_write(&rw);
lockdep_assert_held_exclusive(&rw);
up_write(&rw);
downgrade_write(&rw);
lockdep_assert_held_read(&rw); <-- here
up_read(&rw);
}
I was expecting that lockdep_assert_held_read() splat nothing after
downgrade_write(). Is this warning an intentional behaviour?
Also the final up_read() gives me a warning too. It is produced at
lockdep.c:3514:lock_release(): DEBUG_LOCKS_WARN_ON(depth <= 0)
As an additional information, I increased some lockdep constants.
Do you think this is related?
include/linux/lockdep.h
+#define MAX_LOCKDEP_SUBCLASSES (8UL + 4)
+#define MAX_LOCKDEP_KEYS_BITS (13 + 3)
kernel/locking/lockdep_internals.h
+#define MAX_LOCKDEP_ENTRIES (32768UL << 5)
+#define MAX_LOCKDEP_CHAINS_BITS (16 + 5)
+#define MAX_STACK_TRACE_ENTRIES (524288UL << 5)
J. R. Okajima
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Q: lockdep_assert_held_read() after downgrade_write() "J. R. Okajima" <hooanon05g@gmail.com> - 2017-01-30 22:30 +0100
Re: Q: lockdep_assert_held_read() after downgrade_write() Peter Zijlstra <peterz@infradead.org> - 2017-01-31 12:10 +0100
Re: Q: lockdep_assert_held_read() after downgrade_write() Peter Zijlstra <peterz@infradead.org> - 2017-01-31 15:00 +0100
Re: Q: lockdep_assert_held_read() after downgrade_write() Waiman Long <longman@redhat.com> - 2017-01-31 15:30 +0100
Re: Q: lockdep_assert_held_read() after downgrade_write() Peter Zijlstra <peterz@infradead.org> - 2017-01-31 15:30 +0100
Re: Q: lockdep_assert_held_read() after downgrade_write() "J. R. Okajima" <hooanon05g@gmail.com> - 2017-01-31 16:50 +0100
Re: Q: lockdep_assert_held_read() after downgrade_write() Peter Zijlstra <peterz@infradead.org> - 2017-01-31 18:00 +0100
Re: Q: lockdep_assert_held_read() after downgrade_write() "J. R. Okajima" <hooanon05g@gmail.com> - 2017-02-02 17:40 +0100
[PATCH 1/3] lockdep: consolidate by new find_held_lock() "J. R. Okajima" <hooanon05g@gmail.com> - 2017-02-02 17:50 +0100
[PATCH 3/3] lockdep: new annotation lock_downgrade() "J. R. Okajima" <hooanon05g@gmail.com> - 2017-02-02 17:50 +0100
Re: [PATCH 3/3] lockdep: new annotation lock_downgrade() kbuild test robot <lkp@intel.com> - 2017-02-02 19:10 +0100
Re: [PATCH 3/3] lockdep: new annotation lock_downgrade() Peter Zijlstra <peterz@infradead.org> - 2017-02-02 19:50 +0100
Re: [PATCH 3/3] lockdep: new annotation lock_downgrade() "J. R. Okajima" <hooanon05g@gmail.com> - 2017-02-02 22:10 +0100
[PATCH 2/3] lockdep: consolidate by new validate_held_lock() "J. R. Okajima" <hooanon05g@gmail.com> - 2017-02-02 17:50 +0100
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