This is needed by rust/helpers/srcu.c which now adds rust_helper_srcu_readers_active() as a wrapper around the SRCU helper for Rust callers.
To achive this: 1- Move the srcu_readers_active() implementation from "kernel/rcu/srcutree.c" to "include/linux/srcutree.h". 2- Implement a matching srcu_readers_active() in "include/linux/srcutiny.h" and use it on the existing open-coded WARN_ON() check in cleanup_srcu_struct(). Signed-off-by: Onur Özkan <[email protected]> --- include/linux/srcutiny.h | 13 +++++++++++++ include/linux/srcutree.h | 24 ++++++++++++++++++++++++ kernel/rcu/srcutiny.c | 2 +- kernel/rcu/srcutree.c | 25 ------------------------- rust/helpers/srcu.c | 5 +++++ 5 files changed, 43 insertions(+), 26 deletions(-) diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h index 905b629e8fa3..fbcf13bc12d1 100644 --- a/include/linux/srcutiny.h +++ b/include/linux/srcutiny.h @@ -154,4 +154,17 @@ static inline void srcu_torture_stats_print(struct srcu_struct *ssp, data_race(READ_ONCE(ssp->srcu_idx_max))); } +/** + * srcu_readers_active - returns true if there are readers. and false otherwise. + * @ssp: which srcu_struct to count active readers (holding srcu_read_lock). + * + * Note that this is not an atomic primitive, and can therefore suffer + * severe errors when invoked on an active srcu_struct. That said, it + * can be useful as an error check at cleanup time. + */ +static inline bool srcu_readers_active(struct srcu_struct *ssp) +{ + return READ_ONCE(ssp->srcu_lock_nesting[0]) || READ_ONCE(ssp->srcu_lock_nesting[1]); +} + #endif diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index fd1a9270cb9a..75e54e4f963f 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -374,4 +374,28 @@ static inline void srcu_check_read_flavor(struct srcu_struct *ssp, int read_flav __srcu_check_read_flavor(ssp, read_flavor); } +/** + * srcu_readers_active - returns true if there are readers. and false otherwise. + * @ssp: which srcu_struct to count active readers (holding srcu_read_lock). + * + * Note that this is not an atomic primitive, and can therefore suffer + * severe errors when invoked on an active srcu_struct. That said, it + * can be useful as an error check at cleanup time. + */ +static inline bool srcu_readers_active(struct srcu_struct *ssp) +{ + int cpu; + unsigned long sum = 0; + + for_each_possible_cpu(cpu) { + struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); + + sum += atomic_long_read(&sdp->srcu_ctrs[0].srcu_locks); + sum += atomic_long_read(&sdp->srcu_ctrs[1].srcu_locks); + sum -= atomic_long_read(&sdp->srcu_ctrs[0].srcu_unlocks); + sum -= atomic_long_read(&sdp->srcu_ctrs[1].srcu_unlocks); + } + return sum; +} + #endif diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c index a2e2d516e51b..5dc26af604bf 100644 --- a/kernel/rcu/srcutiny.c +++ b/kernel/rcu/srcutiny.c @@ -85,7 +85,7 @@ EXPORT_SYMBOL_GPL(init_srcu_struct); */ void cleanup_srcu_struct(struct srcu_struct *ssp) { - WARN_ON(ssp->srcu_lock_nesting[0] || ssp->srcu_lock_nesting[1]); + WARN_ON(srcu_readers_active(ssp)); irq_work_sync(&ssp->srcu_irq_work); flush_work(&ssp->srcu_work); WARN_ON(ssp->srcu_gp_running); diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 0d01cd8c4b4a..b1e97ba2e53f 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -598,31 +598,6 @@ static bool srcu_readers_active_idx_check(struct srcu_struct *ssp, int idx) return srcu_readers_lock_idx(ssp, idx, did_gp, unlocks); } -/** - * srcu_readers_active - returns true if there are readers. and false - * otherwise - * @ssp: which srcu_struct to count active readers (holding srcu_read_lock). - * - * Note that this is not an atomic primitive, and can therefore suffer - * severe errors when invoked on an active srcu_struct. That said, it - * can be useful as an error check at cleanup time. - */ -static bool srcu_readers_active(struct srcu_struct *ssp) -{ - int cpu; - unsigned long sum = 0; - - for_each_possible_cpu(cpu) { - struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); - - sum += atomic_long_read(&sdp->srcu_ctrs[0].srcu_locks); - sum += atomic_long_read(&sdp->srcu_ctrs[1].srcu_locks); - sum -= atomic_long_read(&sdp->srcu_ctrs[0].srcu_unlocks); - sum -= atomic_long_read(&sdp->srcu_ctrs[1].srcu_unlocks); - } - return sum; -} - /* * We use an adaptive strategy for synchronize_srcu() and especially for * synchronize_srcu_expedited(). We spin for a fixed time period diff --git a/rust/helpers/srcu.c b/rust/helpers/srcu.c index 79dd24a104ef..fa4b5879dda5 100644 --- a/rust/helpers/srcu.c +++ b/rust/helpers/srcu.c @@ -13,6 +13,11 @@ __rust_helper int rust_helper_init_srcu_struct_with_key(struct srcu_struct *ssp, #endif /* CONFIG_DEBUG_LOCK_ALLOC */ } +__rust_helper bool rust_helper_srcu_readers_active(struct srcu_struct *ssp) +{ + return srcu_readers_active(ssp); +} + __rust_helper int rust_helper_srcu_read_lock(struct srcu_struct *ssp) { return srcu_read_lock(ssp); -- 2.51.2
