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srcu: Check for consistent global per-srcu_struct NMI safety

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This commit adds runtime checks to verify that a given srcu_struct uses
consistent NMI-safe (or not) read-side primitives globally, but based
on the per-CPU data.  These global checks are made by the grace-period
code that must scan the srcu_data structures anyway, and are done only
in kernels built with CONFIG_PROVE_RCU=y.

Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Paul E. McKenney 2022-09-20 14:54:41 -07:00
parent 27120e7d2c
commit 36f65f1d15
1 changed files with 5 additions and 0 deletions
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5
kernel/rcu/srcutree.c
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@ -429,13 +429,18 @@ static unsigned long srcu_readers_lock_idx(struct srcu_struct *ssp, int idx)
static unsigned long srcu_readers_unlock_idx(struct srcu_struct *ssp, int idx)
{
int cpu;
unsigned long mask = 0;
unsigned long sum = 0;
for_each_possible_cpu(cpu) {
struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu);
sum += atomic_long_read(&cpuc->srcu_unlock_count[idx]);
if (IS_ENABLED(CONFIG_PROVE_RCU))
mask = mask | READ_ONCE(cpuc->srcu_nmi_safety);
}
WARN_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && (mask & (mask >> 1)),
"Mixed NMI-safe readers for srcu_struct at %ps.\n", ssp);
return sum;
}