diff options
Diffstat (limited to 'features/rt/net-Qdisc-use-a-seqlock-instead-seqcount.patch')
| -rw-r--r-- | features/rt/net-Qdisc-use-a-seqlock-instead-seqcount.patch | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/features/rt/net-Qdisc-use-a-seqlock-instead-seqcount.patch b/features/rt/net-Qdisc-use-a-seqlock-instead-seqcount.patch new file mode 100644 index 00000000..7ef9f7ad --- /dev/null +++ b/features/rt/net-Qdisc-use-a-seqlock-instead-seqcount.patch @@ -0,0 +1,298 @@ +From 0532faba565e7c8cf62950d7f1a9a7bc7ab9840b Mon Sep 17 00:00:00 2001 +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Wed, 14 Sep 2016 17:36:35 +0200 +Subject: [PATCH 091/191] net/Qdisc: use a seqlock instead seqcount + +The seqcount disables preemption on -RT while it is held which can't +remove. Also we don't want the reader to spin for ages if the writer is +scheduled out. The seqlock on the other hand will serialize / sleep on +the lock while writer is active. + +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + include/net/gen_stats.h | 11 ++++++----- + include/net/net_seq_lock.h | 24 ++++++++++++++++++++++++ + include/net/sch_generic.h | 19 +++++++++++++++++-- + net/core/gen_estimator.c | 6 +++--- + net/core/gen_stats.c | 12 ++++++------ + net/sched/sch_api.c | 2 +- + net/sched/sch_generic.c | 10 ++++++++++ + 7 files changed, 67 insertions(+), 17 deletions(-) + create mode 100644 include/net/net_seq_lock.h + +diff --git a/include/net/gen_stats.h b/include/net/gen_stats.h +index 1424e02cef90..163f8415e5db 100644 +--- a/include/net/gen_stats.h ++++ b/include/net/gen_stats.h +@@ -6,6 +6,7 @@ + #include <linux/socket.h> + #include <linux/rtnetlink.h> + #include <linux/pkt_sched.h> ++#include <net/net_seq_lock.h> + + /* Note: this used to be in include/uapi/linux/gen_stats.h */ + struct gnet_stats_basic_packed { +@@ -42,15 +43,15 @@ int gnet_stats_start_copy_compat(struct sk_buff *skb, int type, + spinlock_t *lock, struct gnet_dump *d, + int padattr); + +-int gnet_stats_copy_basic(const seqcount_t *running, ++int gnet_stats_copy_basic(net_seqlock_t *running, + struct gnet_dump *d, + struct gnet_stats_basic_cpu __percpu *cpu, + struct gnet_stats_basic_packed *b); +-void __gnet_stats_copy_basic(const seqcount_t *running, ++void __gnet_stats_copy_basic(net_seqlock_t *running, + struct gnet_stats_basic_packed *bstats, + struct gnet_stats_basic_cpu __percpu *cpu, + struct gnet_stats_basic_packed *b); +-int gnet_stats_copy_basic_hw(const seqcount_t *running, ++int gnet_stats_copy_basic_hw(net_seqlock_t *running, + struct gnet_dump *d, + struct gnet_stats_basic_cpu __percpu *cpu, + struct gnet_stats_basic_packed *b); +@@ -70,13 +71,13 @@ int gen_new_estimator(struct gnet_stats_basic_packed *bstats, + struct gnet_stats_basic_cpu __percpu *cpu_bstats, + struct net_rate_estimator __rcu **rate_est, + spinlock_t *lock, +- seqcount_t *running, struct nlattr *opt); ++ net_seqlock_t *running, struct nlattr *opt); + void gen_kill_estimator(struct net_rate_estimator __rcu **ptr); + int gen_replace_estimator(struct gnet_stats_basic_packed *bstats, + struct gnet_stats_basic_cpu __percpu *cpu_bstats, + struct net_rate_estimator __rcu **ptr, + spinlock_t *lock, +- seqcount_t *running, struct nlattr *opt); ++ net_seqlock_t *running, struct nlattr *opt); + bool gen_estimator_active(struct net_rate_estimator __rcu **ptr); + bool gen_estimator_read(struct net_rate_estimator __rcu **ptr, + struct gnet_stats_rate_est64 *sample); +diff --git a/include/net/net_seq_lock.h b/include/net/net_seq_lock.h +new file mode 100644 +index 000000000000..95a497a72e51 +--- /dev/null ++++ b/include/net/net_seq_lock.h +@@ -0,0 +1,24 @@ ++#ifndef __NET_NET_SEQ_LOCK_H__ ++#define __NET_NET_SEQ_LOCK_H__ ++ ++#ifdef CONFIG_PREEMPT_RT ++# define net_seqlock_t seqlock_t ++# define net_seq_begin(__r) read_seqbegin(__r) ++# define net_seq_retry(__r, __s) read_seqretry(__r, __s) ++ ++static inline int try_write_seqlock(seqlock_t *sl) ++{ ++ if (spin_trylock(&sl->lock)) { ++ write_seqcount_begin(&sl->seqcount); ++ return 1; ++ } ++ return 0; ++} ++ ++#else ++# define net_seqlock_t seqcount_t ++# define net_seq_begin(__r) read_seqcount_begin(__r) ++# define net_seq_retry(__r, __s) read_seqcount_retry(__r, __s) ++#endif ++ ++#endif +diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h +index 2d6eb60c58c8..1650446d3bfa 100644 +--- a/include/net/sch_generic.h ++++ b/include/net/sch_generic.h +@@ -10,6 +10,7 @@ + #include <linux/percpu.h> + #include <linux/dynamic_queue_limits.h> + #include <linux/list.h> ++#include <net/net_seq_lock.h> + #include <linux/refcount.h> + #include <linux/workqueue.h> + #include <linux/mutex.h> +@@ -100,7 +101,7 @@ struct Qdisc { + struct sk_buff_head gso_skb ____cacheline_aligned_in_smp; + struct qdisc_skb_head q; + struct gnet_stats_basic_packed bstats; +- seqcount_t running; ++ net_seqlock_t running; + struct gnet_stats_queue qstats; + unsigned long state; + struct Qdisc *next_sched; +@@ -141,7 +142,11 @@ static inline bool qdisc_is_running(struct Qdisc *qdisc) + { + if (qdisc->flags & TCQ_F_NOLOCK) + return spin_is_locked(&qdisc->seqlock); ++#ifdef CONFIG_PREEMPT_RT ++ return spin_is_locked(&qdisc->running.lock) ? true : false; ++#else + return (raw_read_seqcount(&qdisc->running) & 1) ? true : false; ++#endif + } + + static inline bool qdisc_is_percpu_stats(const struct Qdisc *q) +@@ -165,17 +170,27 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) + } else if (qdisc_is_running(qdisc)) { + return false; + } ++#ifdef CONFIG_PREEMPT_RT ++ if (try_write_seqlock(&qdisc->running)) ++ return true; ++ return false; ++#else + /* Variant of write_seqcount_begin() telling lockdep a trylock + * was attempted. + */ + raw_write_seqcount_begin(&qdisc->running); + seqcount_acquire(&qdisc->running.dep_map, 0, 1, _RET_IP_); + return true; ++#endif + } + + static inline void qdisc_run_end(struct Qdisc *qdisc) + { ++#ifdef CONFIG_PREEMPT_RT ++ write_sequnlock(&qdisc->running); ++#else + write_seqcount_end(&qdisc->running); ++#endif + if (qdisc->flags & TCQ_F_NOLOCK) + spin_unlock(&qdisc->seqlock); + } +@@ -540,7 +555,7 @@ static inline spinlock_t *qdisc_root_sleeping_lock(const struct Qdisc *qdisc) + return qdisc_lock(root); + } + +-static inline seqcount_t *qdisc_root_sleeping_running(const struct Qdisc *qdisc) ++static inline net_seqlock_t *qdisc_root_sleeping_running(const struct Qdisc *qdisc) + { + struct Qdisc *root = qdisc_root_sleeping(qdisc); + +diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c +index 8e582e29a41e..e51f4854d8b2 100644 +--- a/net/core/gen_estimator.c ++++ b/net/core/gen_estimator.c +@@ -42,7 +42,7 @@ + struct net_rate_estimator { + struct gnet_stats_basic_packed *bstats; + spinlock_t *stats_lock; +- seqcount_t *running; ++ net_seqlock_t *running; + struct gnet_stats_basic_cpu __percpu *cpu_bstats; + u8 ewma_log; + u8 intvl_log; /* period : (250ms << intvl_log) */ +@@ -125,7 +125,7 @@ int gen_new_estimator(struct gnet_stats_basic_packed *bstats, + struct gnet_stats_basic_cpu __percpu *cpu_bstats, + struct net_rate_estimator __rcu **rate_est, + spinlock_t *lock, +- seqcount_t *running, ++ net_seqlock_t *running, + struct nlattr *opt) + { + struct gnet_estimator *parm = nla_data(opt); +@@ -226,7 +226,7 @@ int gen_replace_estimator(struct gnet_stats_basic_packed *bstats, + struct gnet_stats_basic_cpu __percpu *cpu_bstats, + struct net_rate_estimator __rcu **rate_est, + spinlock_t *lock, +- seqcount_t *running, struct nlattr *opt) ++ net_seqlock_t *running, struct nlattr *opt) + { + return gen_new_estimator(bstats, cpu_bstats, rate_est, + lock, running, opt); +diff --git a/net/core/gen_stats.c b/net/core/gen_stats.c +index e491b083b348..ef432cea2e10 100644 +--- a/net/core/gen_stats.c ++++ b/net/core/gen_stats.c +@@ -137,7 +137,7 @@ __gnet_stats_copy_basic_cpu(struct gnet_stats_basic_packed *bstats, + } + + void +-__gnet_stats_copy_basic(const seqcount_t *running, ++__gnet_stats_copy_basic(net_seqlock_t *running, + struct gnet_stats_basic_packed *bstats, + struct gnet_stats_basic_cpu __percpu *cpu, + struct gnet_stats_basic_packed *b) +@@ -150,15 +150,15 @@ __gnet_stats_copy_basic(const seqcount_t *running, + } + do { + if (running) +- seq = read_seqcount_begin(running); ++ seq = net_seq_begin(running); + bstats->bytes = b->bytes; + bstats->packets = b->packets; +- } while (running && read_seqcount_retry(running, seq)); ++ } while (running && net_seq_retry(running, seq)); + } + EXPORT_SYMBOL(__gnet_stats_copy_basic); + + static int +-___gnet_stats_copy_basic(const seqcount_t *running, ++___gnet_stats_copy_basic(net_seqlock_t *running, + struct gnet_dump *d, + struct gnet_stats_basic_cpu __percpu *cpu, + struct gnet_stats_basic_packed *b, +@@ -204,7 +204,7 @@ ___gnet_stats_copy_basic(const seqcount_t *running, + * if the room in the socket buffer was not sufficient. + */ + int +-gnet_stats_copy_basic(const seqcount_t *running, ++gnet_stats_copy_basic(net_seqlock_t *running, + struct gnet_dump *d, + struct gnet_stats_basic_cpu __percpu *cpu, + struct gnet_stats_basic_packed *b) +@@ -228,7 +228,7 @@ EXPORT_SYMBOL(gnet_stats_copy_basic); + * if the room in the socket buffer was not sufficient. + */ + int +-gnet_stats_copy_basic_hw(const seqcount_t *running, ++gnet_stats_copy_basic_hw(net_seqlock_t *running, + struct gnet_dump *d, + struct gnet_stats_basic_cpu __percpu *cpu, + struct gnet_stats_basic_packed *b) +diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c +index f87d07736a14..7a627b208393 100644 +--- a/net/sched/sch_api.c ++++ b/net/sched/sch_api.c +@@ -1258,7 +1258,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev, + rcu_assign_pointer(sch->stab, stab); + } + if (tca[TCA_RATE]) { +- seqcount_t *running; ++ net_seqlock_t *running; + + err = -EOPNOTSUPP; + if (sch->flags & TCQ_F_MQROOT) { +diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c +index 49eae93d1489..512a39d6edec 100644 +--- a/net/sched/sch_generic.c ++++ b/net/sched/sch_generic.c +@@ -553,7 +553,11 @@ struct Qdisc noop_qdisc = { + .ops = &noop_qdisc_ops, + .q.lock = __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock), + .dev_queue = &noop_netdev_queue, ++#ifdef CONFIG_PREEMPT_RT ++ .running = __SEQLOCK_UNLOCKED(noop_qdisc.running), ++#else + .running = SEQCNT_ZERO(noop_qdisc.running), ++#endif + .busylock = __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock), + .gso_skb = { + .next = (struct sk_buff *)&noop_qdisc.gso_skb, +@@ -845,9 +849,15 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, + lockdep_set_class(&sch->busylock, + dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); + ++#ifdef CONFIG_PREEMPT_RT ++ seqlock_init(&sch->running); ++ lockdep_set_class(&sch->running.lock, ++ dev->qdisc_running_key ?: &qdisc_running_key); ++#else + seqcount_init(&sch->running); + lockdep_set_class(&sch->running, + dev->qdisc_running_key ?: &qdisc_running_key); ++#endif + + sch->ops = ops; + sch->flags = ops->static_flags; +-- +2.19.1 + |