On Fri, Sep 8, 2023 at 4:36 PM Frederic Weisbecker <frederic@xxxxxxxxxx> wrote:
>
> The variable name jiffies_till_flush is too generic and therefore:
>
> * It may shadow a global variable
> * It doesn't tell on what it operates
>
> Make the name more precise, along with the related APIs.
>
> Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
> ---
> kernel/rcu/rcu.h | 8 ++++----
> kernel/rcu/rcuscale.c | 6 +++---
> kernel/rcu/tree_nocb.h | 20 ++++++++++----------
> 3 files changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
> index 56a8466a11a2..4ac4daae9917 100644
> --- a/kernel/rcu/rcu.h
> +++ b/kernel/rcu/rcu.h
> @@ -541,11 +541,11 @@ enum rcutorture_type {
> };
>
> #if defined(CONFIG_RCU_LAZY)
> -unsigned long rcu_lazy_get_jiffies_till_flush(void);
> -void rcu_lazy_set_jiffies_till_flush(unsigned long j);
> +unsigned long rcu_get_jiffies_lazy_flush(void);
> +void rcu_set_jiffies_lazy_flush(unsigned long j);
> #else
> -static inline unsigned long rcu_lazy_get_jiffies_till_flush(void) { return 0; }
> -static inline void rcu_lazy_set_jiffies_till_flush(unsigned long j) { }
> +static inline unsigned long rcu_get_jiffies_lazy_flush(void) { return 0; }
> +static inline void rcu_set_jiffies_lazy_flush(unsigned long j) { }
> #endif
>
> #if defined(CONFIG_TREE_RCU)
> diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
> index ffdb30495e3c..8db4fedaaa1e 100644
> --- a/kernel/rcu/rcuscale.c
> +++ b/kernel/rcu/rcuscale.c
> @@ -764,9 +764,9 @@ kfree_scale_init(void)
>
> if (kfree_by_call_rcu) {
> /* do a test to check the timeout. */
> - orig_jif = rcu_lazy_get_jiffies_till_flush();
> + orig_jif = rcu_get_jiffies_lazy_flush();
>
> - rcu_lazy_set_jiffies_till_flush(2 * HZ);
> + rcu_set_jiffies_lazy_flush(2 * HZ);
> rcu_barrier();
>
> jif_start = jiffies;
> @@ -775,7 +775,7 @@ kfree_scale_init(void)
>
> smp_cond_load_relaxed(&rcu_lazy_test1_cb_called, VAL == 1);
>
> - rcu_lazy_set_jiffies_till_flush(orig_jif);
> + rcu_set_jiffies_lazy_flush(orig_jif);
>
> if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
> pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
> diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
> index 5598212d1f27..b9eab359c597 100644
> --- a/kernel/rcu/tree_nocb.h
> +++ b/kernel/rcu/tree_nocb.h
> @@ -264,21 +264,21 @@ static bool wake_nocb_gp(struct rcu_data *rdp, bool force)
> * left unsubmitted to RCU after those many jiffies.
> */
> #define LAZY_FLUSH_JIFFIES (10 * HZ)
> -static unsigned long jiffies_till_flush = LAZY_FLUSH_JIFFIES;
> +static unsigned long jiffies_lazy_flush = LAZY_FLUSH_JIFFIES;
>
> #ifdef CONFIG_RCU_LAZY
> // To be called only from test code.
> -void rcu_lazy_set_jiffies_till_flush(unsigned long jif)
> +void rcu_set_jiffies_lazy_flush(unsigned long jif)
> {
> - jiffies_till_flush = jif;
> + jiffies_lazy_flush = jif;
> }
> -EXPORT_SYMBOL(rcu_lazy_set_jiffies_till_flush);
> +EXPORT_SYMBOL(rcu_set_jiffies_lazy_flush);
>
> -unsigned long rcu_lazy_get_jiffies_till_flush(void)
> +unsigned long rcu_get_jiffies_lazy_flush(void)
> {
> - return jiffies_till_flush;
> + return jiffies_lazy_flush;
> }
> -EXPORT_SYMBOL(rcu_lazy_get_jiffies_till_flush);
> +EXPORT_SYMBOL(rcu_get_jiffies_lazy_flush);
> #endif
>
> /*
While at it, could we replace jiffies_lazy_flush with
rcu_get_jiffies_lazy_flush() in the below? That way all users are
going through the API.
With that,
Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
thanks,
- Joel
> @@ -299,7 +299,7 @@ static void wake_nocb_gp_defer(struct rcu_data *rdp, int waketype,
> */
> if (waketype == RCU_NOCB_WAKE_LAZY &&
> rdp->nocb_defer_wakeup == RCU_NOCB_WAKE_NOT) {
> - mod_timer(&rdp_gp->nocb_timer, jiffies + jiffies_till_flush);
> + mod_timer(&rdp_gp->nocb_timer, jiffies + jiffies_lazy_flush);
> WRITE_ONCE(rdp_gp->nocb_defer_wakeup, waketype);
> } else if (waketype == RCU_NOCB_WAKE_BYPASS) {
> mod_timer(&rdp_gp->nocb_timer, jiffies + 2);
> @@ -482,7 +482,7 @@ static bool rcu_nocb_try_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
> // flush ->nocb_bypass to ->cblist.
> if ((ncbs && !bypass_is_lazy && j != READ_ONCE(rdp->nocb_bypass_first)) ||
> (ncbs && bypass_is_lazy &&
> - (time_after(j, READ_ONCE(rdp->nocb_bypass_first) + jiffies_till_flush))) ||
> + (time_after(j, READ_ONCE(rdp->nocb_bypass_first) + jiffies_lazy_flush))) ||
> ncbs >= qhimark) {
> rcu_nocb_lock(rdp);
> *was_alldone = !rcu_segcblist_pend_cbs(&rdp->cblist);
> @@ -723,7 +723,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
> lazy_ncbs = READ_ONCE(rdp->lazy_len);
>
> if (bypass_ncbs && (lazy_ncbs == bypass_ncbs) &&
> - (time_after(j, READ_ONCE(rdp->nocb_bypass_first) + jiffies_till_flush) ||
> + (time_after(j, READ_ONCE(rdp->nocb_bypass_first) + jiffies_lazy_flush) ||
> bypass_ncbs > 2 * qhimark)) {
> flush_bypass = true;
> } else if (bypass_ncbs && (lazy_ncbs != bypass_ncbs) &&
> --
> 2.41.0
>
