The following commit has been merged into the core/rcu branch of tip: Commit-ID: 1a893c711a600ab57526619b56e6f6b7be00956e Gitweb: https://git.kernel.org/tip/1a893c711a600ab57526619b56e6f6b7be00956e Author: Paul E. McKenney <paul...@kernel.org> AuthorDate: Fri, 13 Nov 2020 09:37:39 -08:00 Committer: Paul E. McKenney <paul...@kernel.org> CommitterDate: Mon, 04 Jan 2021 13:53:37 -08:00
srcu: Provide internal interface to start a Tiny SRCU grace period 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/20201112201547.gf3365...@moria.home.lan/ Reported-by: Kent Overstreet <kent.overstr...@gmail.com> Reviewed-by: Neeraj Upadhyay <neer...@codeaurora.org> Signed-off-by: Paul E. McKenney <paul...@kernel.org> --- 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);
