rcu: Add full-sized polling for cond_sync_exp_full()

The cond_synchronize_rcu_expedited() API compresses the combined expedited and
normal grace-period states into a single unsigned long, which conserves
storage, but can miss grace periods in certain cases involving overlapping
normal and expedited grace periods.  Missing the occasional grace period
is usually not a problem, but there are use cases that care about each
and every grace period.

This commit therefore adds yet another member of the full-state RCU
grace-period polling API, which is the cond_synchronize_rcu_exp_full()
function.  This uses up to three times the storage (rcu_gp_oldstate
structure instead of unsigned long), but is guaranteed not to miss
grace periods.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney
2022-08-04 15:23:26 -07:00
parent b6fe4917ae
commit 8df13f0160
4 changed files with 83 additions and 22 deletions

View File

@@ -64,6 +64,11 @@ static inline void cond_synchronize_rcu_expedited(unsigned long oldstate)
cond_synchronize_rcu(oldstate);
}
static inline void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp)
{
cond_synchronize_rcu_expedited(rgosp->rgos_norm);
}
extern void rcu_barrier(void);
static inline void synchronize_rcu_expedited(void)