From: "Paul E. McKenney" paulmck@kernel.org
mainline inclusion from mainline-5.10.62 commit 641e1d88404a57983c75cc39b9feb076f5cdeac8 bugzilla: 182217 https://gitee.com/openeuler/kernel/issues/I4EFOS
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
--------------------------------
commit 1a893c711a600ab57526619b56e6f6b7be00956e upstream.
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.GF3365678@moria.home.lan/ Reported-by: Kent Overstreet kent.overstreet@gmail.com Reviewed-by: Neeraj Upadhyay neeraju@codeaurora.org Signed-off-by: Paul E. McKenney paulmck@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Chen Jun chenjun102@huawei.com Acked-by: Weilong Chen chenweilong@huawei.com
Signed-off-by: Chen Jun chenjun102@huawei.com --- 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 6208c1dae5c9..ee25b365c3ea 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -151,6 +151,16 @@ 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. @@ -166,12 +176,7 @@ 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);