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| author |   Paul E. McKenney <paulmck@kernel.org> | 2022-05-17 11:30:32 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-06-20 09:22:28 -0700 |
| commit | 0356d4e66214569de674ab2684f2e0b440a466ab (patch) | |
| tree | feb5195f3661d9dedb2c443f13d8d24285cde5e9 /include | |
| parent | rcu-tasks: Add data structures for lightweight grace periods (diff) | |
| download | wireguard-linux-0356d4e66214569de674ab2684f2e0b440a466ab.tar.xz wireguard-linux-0356d4e66214569de674ab2684f2e0b440a466ab.zip | |
rcu-tasks: Track blocked RCU Tasks Trace readers
This commit places any task that has ever blocked within its current
RCU Tasks Trace read-side critical section on a per-CPU list within the
rcu_tasks_percpu structure. Tasks are removed from this list when they
exit by the exit_tasks_rcu_finish_trace() function. The purpose of this
commit is to provide the information needed to eliminate the current
scan of the full task list.
This commit offsets the INT_MIN value for ->trc_reader_nesting with the
new nesting level in order to avoid queueing tasks that are exiting
their read-side critical sections.
[ paulmck: Apply kernel test robot feedback. ]
[ paulmck: Apply feedback from syzbot+9bb26e7c5e8e4fa7e641@syzkaller.appspotmail.com ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: syzbot <syzbot+9bb26e7c5e8e4fa7e641@syzkaller.appspotmail.com>
Tested-by: "Zhang, Qiang1" <qiang1.zhang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/rcupdate.h | 11 | ||||
| -rw-r--r-- | include/linux/rcupdate_trace.h | 2 |
2 files changed, 10 insertions, 3 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 1e728d544fc1..ebdfeead44e5 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -174,12 +174,19 @@ void synchronize_rcu_tasks(void); #define TRC_NEED_QS_CHECKED 0x2 // Task has been checked for needing quiescent state. u8 rcu_trc_cmpxchg_need_qs(struct task_struct *t, u8 old, u8 new); +void rcu_tasks_trace_qs_blkd(struct task_struct *t); # define rcu_tasks_trace_qs(t) \ do { \ + int ___rttq_nesting = READ_ONCE((t)->trc_reader_nesting); \ + \ if (likely(!READ_ONCE((t)->trc_reader_special.b.need_qs)) && \ - likely(!READ_ONCE((t)->trc_reader_nesting))) \ + likely(!___rttq_nesting)) { \ rcu_trc_cmpxchg_need_qs((t), 0, TRC_NEED_QS_CHECKED); \ + } else if (___rttq_nesting && ___rttq_nesting != INT_MIN && \ + !READ_ONCE((t)->trc_reader_special.b.blocked)) { \ + rcu_tasks_trace_qs_blkd(t); \ + } \ } while (0) # else # define rcu_tasks_trace_qs(t) do { } while (0) @@ -188,7 +195,7 @@ u8 rcu_trc_cmpxchg_need_qs(struct task_struct *t, u8 old, u8 new); #define rcu_tasks_qs(t, preempt) \ do { \ rcu_tasks_classic_qs((t), (preempt)); \ - rcu_tasks_trace_qs((t)); \ + rcu_tasks_trace_qs(t); \ } while (0) # ifdef CONFIG_TASKS_RUDE_RCU diff --git a/include/linux/rcupdate_trace.h b/include/linux/rcupdate_trace.h index 6f9c35817398..9bc8cbb33340 100644 --- a/include/linux/rcupdate_trace.h +++ b/include/linux/rcupdate_trace.h @@ -75,7 +75,7 @@ static inline void rcu_read_unlock_trace(void) nesting = READ_ONCE(t->trc_reader_nesting) - 1; barrier(); // Critical section before disabling. // Disable IPI-based setting of .need_qs. - WRITE_ONCE(t->trc_reader_nesting, INT_MIN); + WRITE_ONCE(t->trc_reader_nesting, INT_MIN + nesting); if (likely(!READ_ONCE(t->trc_reader_special.s)) || nesting) { WRITE_ONCE(t->trc_reader_nesting, nesting); return; // We assume shallow reader nesting. |