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| author | Frederic Weisbecker <frederic@kernel.org> | 2021-10-11 17:51:30 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-12-08 03:24:44 +0300 |
| commit | 118e0d4a1bc85d4ecea0427e440a72d21ffbfa6a (patch) | |
| tree | 201c06531e250335ce5120a0331ed0c301f13a05 /kernel/rcu/rcu_segcblist.h | |
| parent | 614ddad17f22a22e035e2ea37a04815f50362017 (diff) | |
| download | linux-118e0d4a1bc85d4ecea0427e440a72d21ffbfa6a.tar.xz | |
rcu/nocb: Make local rcu_nocb_lock_irqsave() safe against concurrent deoffloading
rcu_nocb_lock_irqsave() can be preempted between the call to
rcu_segcblist_is_offloaded() and the actual locking. This matters now
that rcu_core() is preemptible on PREEMPT_RT and the (de-)offloading
process can interrupt the softirq or the rcuc kthread.
As a result we may locklessly call into code that requires nocb locking.
In practice this is a problem while we accelerate callbacks on rcu_core().
Simply disabling interrupts before (instead of after) checking the NOCB
offload state fixes the issue.
Reported-and-tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/rcu_segcblist.h')
0 files changed, 0 insertions, 0 deletions