diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2022-09-15 12:09:30 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-10-18 11:24:24 -0700 |
| commit | 5d0f5953b60f5f7a278085b55ddc73e2932f4c33 (patch) | |
| tree | 1c5dc06211ff365e53b5ccab84f23821dee2da21 /kernel/rcu | |
| parent | 9abf2313adc1ca1b6180c508c25f22f9395cc780 (diff) | |
srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic
NMI-safe variants of srcu_read_lock() and srcu_read_unlock() are needed
by printk(), which on many architectures entails read-modify-write
atomic operations. This commit prepares Tree SRCU for this change by
making both ->srcu_lock_count and ->srcu_unlock_count by atomic_long_t.
[ paulmck: Apply feedback from John Ogness. ]
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>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/srcutree.c | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 1c304fec89c0..25e9458da6a2 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -417,7 +417,7 @@ static unsigned long srcu_readers_lock_idx(struct srcu_struct *ssp, int idx) for_each_possible_cpu(cpu) { struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu); - sum += READ_ONCE(cpuc->srcu_lock_count[idx]); + sum += atomic_long_read(&cpuc->srcu_lock_count[idx]); } return sum; } @@ -434,7 +434,7 @@ static unsigned long srcu_readers_unlock_idx(struct srcu_struct *ssp, int idx) for_each_possible_cpu(cpu) { struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu); - sum += READ_ONCE(cpuc->srcu_unlock_count[idx]); + sum += atomic_long_read(&cpuc->srcu_unlock_count[idx]); } return sum; } @@ -503,10 +503,10 @@ static bool srcu_readers_active(struct srcu_struct *ssp) for_each_possible_cpu(cpu) { struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu); - sum += READ_ONCE(cpuc->srcu_lock_count[0]); - sum += READ_ONCE(cpuc->srcu_lock_count[1]); - sum -= READ_ONCE(cpuc->srcu_unlock_count[0]); - sum -= READ_ONCE(cpuc->srcu_unlock_count[1]); + sum += atomic_long_read(&cpuc->srcu_lock_count[0]); + sum += atomic_long_read(&cpuc->srcu_lock_count[1]); + sum -= atomic_long_read(&cpuc->srcu_unlock_count[0]); + sum -= atomic_long_read(&cpuc->srcu_unlock_count[1]); } return sum; } @@ -636,7 +636,7 @@ int __srcu_read_lock(struct srcu_struct *ssp) int idx; idx = READ_ONCE(ssp->srcu_idx) & 0x1; - this_cpu_inc(ssp->sda->srcu_lock_count[idx]); + this_cpu_inc(ssp->sda->srcu_lock_count[idx].counter); smp_mb(); /* B */ /* Avoid leaking the critical section. */ return idx; } @@ -650,7 +650,7 @@ EXPORT_SYMBOL_GPL(__srcu_read_lock); void __srcu_read_unlock(struct srcu_struct *ssp, int idx) { smp_mb(); /* C */ /* Avoid leaking the critical section. */ - this_cpu_inc(ssp->sda->srcu_unlock_count[idx]); + this_cpu_inc(ssp->sda->srcu_unlock_count[idx].counter); } EXPORT_SYMBOL_GPL(__srcu_read_unlock); @@ -1687,8 +1687,8 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf) struct srcu_data *sdp; sdp = per_cpu_ptr(ssp->sda, cpu); - u0 = data_race(sdp->srcu_unlock_count[!idx]); - u1 = data_race(sdp->srcu_unlock_count[idx]); + u0 = data_race(atomic_long_read(&sdp->srcu_unlock_count[!idx])); + u1 = data_race(atomic_long_read(&sdp->srcu_unlock_count[idx])); /* * Make sure that a lock is always counted if the corresponding @@ -1696,8 +1696,8 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf) */ smp_rmb(); - l0 = data_race(sdp->srcu_lock_count[!idx]); - l1 = data_race(sdp->srcu_lock_count[idx]); + l0 = data_race(atomic_long_read(&sdp->srcu_lock_count[!idx])); + l1 = data_race(atomic_long_read(&sdp->srcu_lock_count[idx])); c0 = l0 - u0; c1 = l1 - u1; |