linux/kernel/rcu/srcutree.c, branch v5.8

srcu: Add data_race() to ->srcu_lock_count and ->srcu_unlock_count arrays

2020-04-27T18:01:16Z

The srcu_data structure's ->srcu_lock_count and ->srcu_unlock_count arrays are read and written locklessly, so this commit adds the data_race() to the diagnostic-print loads from these arrays in order mark them as known and approved data-racy accesses. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely and due to this being used only by rcutorture. Signed-off-by: Paul E. McKenney

srcu: Add KCSAN stubs

2020-04-27T18:01:15Z

This commit adds stubs for KCSAN's data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS() macros to allow code using these macros to move ahead. Signed-off-by: Paul E. McKenney

Merge branches 'doc.2020.02.27a', 'fixes.2020.03.21a', 'kfree_rcu.2020.02.20a', 'locktorture.2020.02.20a', 'ovld.2020.02.20a', 'rcu-tasks.2020.02.20a', 'srcu.2020.02.20a' and 'torture.2020.02.20a' into HEAD

2020-03-22T00:15:11Z

doc.2020.02.27a: Documentation updates. fixes.2020.03.21a: Miscellaneous fixes. kfree_rcu.2020.02.20a: Updates to kfree_rcu(). locktorture.2020.02.20a: Lock torture-test updates. ovld.2020.02.20a: Updates to callback-overload handling. rcu-tasks.2020.02.20a: RCU-tasks updates. srcu.2020.02.20a: SRCU updates. torture.2020.02.20a: Torture-test updates.

srcu: Hold srcu_struct ->lock when updating ->srcu_gp_seq

2020-02-21T00:01:11Z

A read of the srcu_struct structure's ->srcu_gp_seq field should not need READ_ONCE() when that structure's ->lock is held. Except that this lock is not always held when updating this field. This commit therefore acquires the lock around updates and removes a now-unneeded READ_ONCE(). This data race was reported by KCSAN. Signed-off-by: Paul E. McKenney [ paulmck: Switch from READ_ONCE() to lock per Peter Zilstra question. ] Acked-by: Peter Zijlstra (Intel)

srcu: Fix process_srcu()/srcu_batches_completed() datarace

2020-02-21T00:01:11Z

The srcu_struct structure's ->srcu_idx field is accessed locklessly, so reads must use READ_ONCE(). This commit therefore adds the needed READ_ONCE() invocation where it was missed. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely. Signed-off-by: Paul E. McKenney

srcu: Fix __call_srcu()/srcu_get_delay() datarace

2020-02-21T00:01:11Z

The srcu_struct structure's ->srcu_gp_seq_needed_exp field is accessed locklessly, so updates must use WRITE_ONCE(). This commit therefore adds the needed WRITE_ONCE() invocations. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely. Signed-off-by: Paul E. McKenney

srcu: Fix __call_srcu()/process_srcu() datarace

2020-02-21T00:01:11Z

The srcu_node structure's ->srcu_gp_seq_needed_exp field is accessed locklessly, so updates must use WRITE_ONCE(). This commit therefore adds the needed WRITE_ONCE() invocations. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely. Signed-off-by: Paul E. McKenney

rcu: Fix typos in file-header comments

2020-02-20T23:58:22Z

Convert to plural and add a note that this is for Tree RCU. Signed-off-by: SeongJae Park Signed-off-by: Paul E. McKenney

Merge branches 'doc.2019.12.10a', 'exp.2019.12.09a', 'fixes.2020.01.24a', 'kfree_rcu.2020.01.24a', 'list.2020.01.10a', 'preempt.2020.01.24a' and 'torture.2019.12.09a' into HEAD

2020-01-24T18:37:27Z

doc.2019.12.10a: Documentations updates exp.2019.12.09a: Expedited grace-period updates fixes.2020.01.24a: Miscellaneous fixes kfree_rcu.2020.01.24a: Batch kfree_rcu() work list.2020.01.10a: RCU-protected-list updates preempt.2020.01.24a: Preemptible RCU updates torture.2019.12.09a: Torture-test updates

srcu: Apply *_ONCE() to ->srcu_last_gp_end

2020-01-24T18:33:51Z

The ->srcu_last_gp_end field is accessed from any CPU at any time by synchronize_srcu(), so non-initialization references need to use READ_ONCE() and WRITE_ONCE(). This commit therefore makes that change. Reported-by: syzbot+08f3e9d26e5541e1ecf2@syzkaller.appspotmail.com Acked-by: Marco Elver Signed-off-by: Paul E. McKenney