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SRCU disables interrupts to get a stable per-CPU pointer and then acquires the spinlock which is in the per-CPU data structure. The release uses spin_unlock_irqrestore(). While this is correct on a non-RT kernel, this conflicts with the RT semantics because the spinlock is converted to a 'sleeping' spinlock. Sleeping locks can obviously not be acquired with interrupts disabled. Acquire the per-CPU pointer `ssp->sda' without disabling preemption and then acquire the spinlock_t of the per-CPU data structure. The lock will ensure that the data is consistent. The added call to check_init_srcu_struct() is now needed because a statically defined srcu_struct may remain uninitialized until this point and the newly introduced locking operation requires an initialized spinlock_t. This change was tested for four hours with 8*SRCU-N and 8*SRCU-P without causing any warnings. Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: rcu@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> |
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| .. | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| rcu_segcblist.c | ||
| rcu_segcblist.h | ||
| rcu.h | ||
| rcuperf.c | ||
| rcutorture.c | ||
| srcutiny.c | ||
| srcutree.c | ||
| sync.c | ||
| tasks.h | ||
| tiny.c | ||
| tree_exp.h | ||
| tree_plugin.h | ||
| tree_stall.h | ||
| tree.c | ||
| tree.h | ||
| update.c | ||