From: "Paul E. McKenney" <[email protected]> There is a need for a polling interface for SRCU grace periods. This polling needs to initiate an SRCU grace period without having to queue (and manage) a callback. This commit therefore splits the Tiny SRCU call_srcu() function into callback-queuing and start-grace-period portions, with the latter in a new function named srcu_gp_start_if_needed().
Link: https://lore.kernel.org/rcu/[email protected]/ Reported-by: Kent Overstreet <[email protected]> Reviewed-by: Neeraj Upadhyay <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/srcutiny.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index 5598cf6..3bac1db 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -152,6 +152,16 @@ void srcu_drive_gp(struct work_struct *wp) } EXPORT_SYMBOL_GPL(srcu_drive_gp); +static void srcu_gp_start_if_needed(struct srcu_struct *ssp) +{ + if (!READ_ONCE(ssp->srcu_gp_running)) { + if (likely(srcu_init_done)) + schedule_work(&ssp->srcu_work); + else if (list_empty(&ssp->srcu_work.entry)) + list_add(&ssp->srcu_work.entry, &srcu_boot_list); + } +} + /* * Enqueue an SRCU callback on the specified srcu_struct structure, * initiating grace-period processing if it is not already running. @@ -167,12 +177,7 @@ void call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp, *ssp->srcu_cb_tail = rhp; ssp->srcu_cb_tail = &rhp->next; local_irq_restore(flags); - if (!READ_ONCE(ssp->srcu_gp_running)) { - if (likely(srcu_init_done)) - schedule_work(&ssp->srcu_work); - else if (list_empty(&ssp->srcu_work.entry)) - list_add(&ssp->srcu_work.entry, &srcu_boot_list); - } + srcu_gp_start_if_needed(ssp); } EXPORT_SYMBOL_GPL(call_srcu); -- 2.9.5
