srcu: Move ->lock from srcu_struct to srcu_usage

This commit moves the ->lock field from the srcu_struct structure to
the srcu_usage structure to reduce the size of the former in order to
improve cache locality.

Suggested-by: Christoph Hellwig <hch@lst.de>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Tested-by: "Zhang, Qiang1" <qiang1.zhang@intel.com>
Tested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 231de66ceb158ef1de69b6cc75972e543d33efe8..694d87b819175b71bfae03664d7dc2abd64ec857 100644 (file)
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -66,13 +66,13 @@ struct srcu_usage {
                                                /* First node at each level. */
        int srcu_size_state;                    /* Small-to-big transition state. */
        struct mutex srcu_cb_mutex;             /* Serialize CB preparation. */
+       spinlock_t __private lock;              /* Protect counters and size state. */
 };
 
 /*
  * Per-SRCU-domain structure, similar in function to rcu_state.
  */
 struct srcu_struct {
-       spinlock_t __private lock;              /* Protect counters and size state. */
        struct mutex srcu_gp_mutex;             /* Serialize GP work. */
        unsigned int srcu_idx;                  /* Current rdr array element. */
        unsigned long srcu_gp_seq;              /* Grace-period seq #. */
@@ -116,7 +116,6 @@ struct srcu_struct {
 #define SRCU_STATE_SCAN2       2
 
 #define __SRCU_STRUCT_INIT_COMMON(name, usage_name)                                            \
-       .lock = __SPIN_LOCK_UNLOCKED(name.lock),                                                \
        .srcu_gp_seq_needed = -1UL,                                                             \
        .work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0),                                 \
        .srcu_sup = &usage_name,                                                                \
@@ -154,7 +153,9 @@ struct srcu_struct {
  */
 #ifdef MODULE
 # define __DEFINE_SRCU(name, is_static)                                                                \
-       static struct srcu_usage name##_srcu_usage;                                             \
+       static struct srcu_usage name##_srcu_usage = {                                          \
+               .lock = __SPIN_LOCK_UNLOCKED(name.lock),                                        \
+       };                                                                                      \
        is_static struct srcu_struct name = __SRCU_STRUCT_INIT_MODULE(name, name##_srcu_usage); \
        extern struct srcu_struct * const __srcu_struct_##name;                                 \
        struct srcu_struct * const __srcu_struct_##name                                         \
@@ -162,7 +163,9 @@ struct srcu_struct {
 #else
 # define __DEFINE_SRCU(name, is_static)                                                                \
        static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);                              \
-       static struct srcu_usage name##_srcu_usage;                                             \
+       static struct srcu_usage name##_srcu_usage = {                                          \
+               .lock = __SPIN_LOCK_UNLOCKED(name.lock),                                        \
+       };                                                                                      \
        is_static struct srcu_struct name =                                                     \
                __SRCU_STRUCT_INIT(name, name##_srcu_usage, name##_srcu_data)
 #endif

diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index c2a024a60f1aab29bb32b21b434b8f722b9d8fc2..c42248cf18f62080a75628020cfcb1c3d7c265d6 100644 (file)
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -103,7 +103,7 @@ do {                                                                                \
 
 #define spin_trylock_irqsave_rcu_node(p, flags)                                        \
 ({                                                                             \
-       bool ___locked = spin_trylock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \
+       bool ___locked = spin_trylock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \
                                                                                \
        if (___locked)                                                          \
                smp_mb__after_unlock_lock();                                    \
@@ -241,7 +241,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
        if (!ssp->srcu_sup)
                return -ENOMEM;
        if (!is_static)
-               spin_lock_init(&ACCESS_PRIVATE(ssp, lock));
+               spin_lock_init(&ACCESS_PRIVATE(ssp->srcu_sup, lock));
        ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
        ssp->srcu_sup->node = NULL;
        mutex_init(&ssp->srcu_sup->srcu_cb_mutex);
@@ -314,7 +314,7 @@ EXPORT_SYMBOL_GPL(init_srcu_struct);
  */
 static void __srcu_transition_to_big(struct srcu_struct *ssp)
 {
-       lockdep_assert_held(&ACCESS_PRIVATE(ssp, lock));
+       lockdep_assert_held(&ACCESS_PRIVATE(ssp->srcu_sup, lock));
        smp_store_release(&ssp->srcu_sup->srcu_size_state, SRCU_SIZE_ALLOC);
 }
 
@@ -328,13 +328,13 @@ static void srcu_transition_to_big(struct srcu_struct *ssp)
        /* Double-checked locking on ->srcu_size-state. */
        if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) != SRCU_SIZE_SMALL)
                return;
-       spin_lock_irqsave_rcu_node(ssp, flags);
+       spin_lock_irqsave_rcu_node(ssp->srcu_sup, flags);
        if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) != SRCU_SIZE_SMALL) {
-               spin_unlock_irqrestore_rcu_node(ssp, flags);
+               spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, flags);
                return;
        }
        __srcu_transition_to_big(ssp);
-       spin_unlock_irqrestore_rcu_node(ssp, flags);
+       spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, flags);
 }
 
 /*
@@ -369,9 +369,9 @@ static void spin_lock_irqsave_sdp_contention(struct srcu_data *sdp, unsigned lon
 
        if (spin_trylock_irqsave_rcu_node(sdp, *flags))
                return;
-       spin_lock_irqsave_rcu_node(ssp, *flags);
+       spin_lock_irqsave_rcu_node(ssp->srcu_sup, *flags);
        spin_lock_irqsave_check_contention(ssp);
-       spin_unlock_irqrestore_rcu_node(ssp, *flags);
+       spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, *flags);
        spin_lock_irqsave_rcu_node(sdp, *flags);
 }
 
@@ -383,9 +383,9 @@ static void spin_lock_irqsave_sdp_contention(struct srcu_data *sdp, unsigned lon
  */
 static void spin_lock_irqsave_ssp_contention(struct srcu_struct *ssp, unsigned long *flags)
 {
-       if (spin_trylock_irqsave_rcu_node(ssp, *flags))
+       if (spin_trylock_irqsave_rcu_node(ssp->srcu_sup, *flags))
                return;
-       spin_lock_irqsave_rcu_node(ssp, *flags);
+       spin_lock_irqsave_rcu_node(ssp->srcu_sup, *flags);
        spin_lock_irqsave_check_contention(ssp);
 }
 
@@ -404,13 +404,13 @@ static void check_init_srcu_struct(struct srcu_struct *ssp)
        /* The smp_load_acquire() pairs with the smp_store_release(). */
        if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_gp_seq_needed))) /*^^^*/
                return; /* Already initialized. */
-       spin_lock_irqsave_rcu_node(ssp, flags);
+       spin_lock_irqsave_rcu_node(ssp->srcu_sup, flags);
        if (!rcu_seq_state(ssp->srcu_gp_seq_needed)) {
-               spin_unlock_irqrestore_rcu_node(ssp, flags);
+               spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, flags);
                return;
        }
        init_srcu_struct_fields(ssp, true);
-       spin_unlock_irqrestore_rcu_node(ssp, flags);
+       spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, flags);
 }
 
 /*
@@ -774,7 +774,7 @@ static void srcu_gp_start(struct srcu_struct *ssp)
                sdp = per_cpu_ptr(ssp->sda, get_boot_cpu_id());
        else
                sdp = this_cpu_ptr(ssp->sda);
-       lockdep_assert_held(&ACCESS_PRIVATE(ssp, lock));
+       lockdep_assert_held(&ACCESS_PRIVATE(ssp->srcu_sup, lock));
        WARN_ON_ONCE(ULONG_CMP_GE(ssp->srcu_gp_seq, ssp->srcu_gp_seq_needed));
        spin_lock_rcu_node(sdp);  /* Interrupts already disabled. */
        rcu_segcblist_advance(&sdp->srcu_cblist,
@@ -864,7 +864,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
        mutex_lock(&ssp->srcu_sup->srcu_cb_mutex);
 
        /* End the current grace period. */
-       spin_lock_irq_rcu_node(ssp);
+       spin_lock_irq_rcu_node(ssp->srcu_sup);
        idx = rcu_seq_state(ssp->srcu_gp_seq);
        WARN_ON_ONCE(idx != SRCU_STATE_SCAN2);
        if (ULONG_CMP_LT(READ_ONCE(ssp->srcu_gp_seq), READ_ONCE(ssp->srcu_gp_seq_needed_exp)))
@@ -875,7 +875,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
        gpseq = rcu_seq_current(&ssp->srcu_gp_seq);
        if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, gpseq))
                WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, gpseq);
-       spin_unlock_irq_rcu_node(ssp);
+       spin_unlock_irq_rcu_node(ssp->srcu_sup);
        mutex_unlock(&ssp->srcu_gp_mutex);
        /* A new grace period can start at this point.  But only one. */
 
@@ -924,15 +924,15 @@ static void srcu_gp_end(struct srcu_struct *ssp)
        mutex_unlock(&ssp->srcu_sup->srcu_cb_mutex);
 
        /* Start a new grace period if needed. */
-       spin_lock_irq_rcu_node(ssp);
+       spin_lock_irq_rcu_node(ssp->srcu_sup);
        gpseq = rcu_seq_current(&ssp->srcu_gp_seq);
        if (!rcu_seq_state(gpseq) &&
            ULONG_CMP_LT(gpseq, ssp->srcu_gp_seq_needed)) {
                srcu_gp_start(ssp);
-               spin_unlock_irq_rcu_node(ssp);
+               spin_unlock_irq_rcu_node(ssp->srcu_sup);
                srcu_reschedule(ssp, 0);
        } else {
-               spin_unlock_irq_rcu_node(ssp);
+               spin_unlock_irq_rcu_node(ssp->srcu_sup);
        }
 
        /* Transition to big if needed. */
@@ -975,7 +975,7 @@ static void srcu_funnel_exp_start(struct srcu_struct *ssp, struct srcu_node *snp
        spin_lock_irqsave_ssp_contention(ssp, &flags);
        if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, s))
                WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, s);
-       spin_unlock_irqrestore_rcu_node(ssp, flags);
+       spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, flags);
 }
 
 /*
@@ -1064,7 +1064,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp,
                else if (list_empty(&ssp->work.work.entry))
                        list_add(&ssp->work.work.entry, &srcu_boot_list);
        }
-       spin_unlock_irqrestore_rcu_node(ssp, flags);
+       spin_unlock_irqrestore_rcu_node(ssp->srcu_sup, flags);
 }
 
 /*
@@ -1599,17 +1599,17 @@ static void srcu_advance_state(struct srcu_struct *ssp)
         */
        idx = rcu_seq_state(smp_load_acquire(&ssp->srcu_gp_seq)); /* ^^^ */
        if (idx == SRCU_STATE_IDLE) {
-               spin_lock_irq_rcu_node(ssp);
+               spin_lock_irq_rcu_node(ssp->srcu_sup);
                if (ULONG_CMP_GE(ssp->srcu_gp_seq, ssp->srcu_gp_seq_needed)) {
                        WARN_ON_ONCE(rcu_seq_state(ssp->srcu_gp_seq));
-                       spin_unlock_irq_rcu_node(ssp);
+                       spin_unlock_irq_rcu_node(ssp->srcu_sup);
                        mutex_unlock(&ssp->srcu_gp_mutex);
                        return;
                }
                idx = rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq));
                if (idx == SRCU_STATE_IDLE)
                        srcu_gp_start(ssp);
-               spin_unlock_irq_rcu_node(ssp);
+               spin_unlock_irq_rcu_node(ssp->srcu_sup);
                if (idx != SRCU_STATE_IDLE) {
                        mutex_unlock(&ssp->srcu_gp_mutex);
                        return; /* Someone else started the grace period. */
@@ -1623,10 +1623,10 @@ static void srcu_advance_state(struct srcu_struct *ssp)
                        return; /* readers present, retry later. */
                }
                srcu_flip(ssp);
-               spin_lock_irq_rcu_node(ssp);
+               spin_lock_irq_rcu_node(ssp->srcu_sup);
                rcu_seq_set_state(&ssp->srcu_gp_seq, SRCU_STATE_SCAN2);
                ssp->srcu_n_exp_nodelay = 0;
-               spin_unlock_irq_rcu_node(ssp);
+               spin_unlock_irq_rcu_node(ssp->srcu_sup);
        }
 
        if (rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) == SRCU_STATE_SCAN2) {
@@ -1710,7 +1710,7 @@ static void srcu_reschedule(struct srcu_struct *ssp, unsigned long delay)
 {
        bool pushgp = true;
 
-       spin_lock_irq_rcu_node(ssp);
+       spin_lock_irq_rcu_node(ssp->srcu_sup);
        if (ULONG_CMP_GE(ssp->srcu_gp_seq, ssp->srcu_gp_seq_needed)) {
                if (!WARN_ON_ONCE(rcu_seq_state(ssp->srcu_gp_seq))) {
                        /* All requests fulfilled, time to go idle. */
@@ -1720,7 +1720,7 @@ static void srcu_reschedule(struct srcu_struct *ssp, unsigned long delay)
                /* Outstanding request and no GP.  Start one. */
                srcu_gp_start(ssp);
        }
-       spin_unlock_irq_rcu_node(ssp);
+       spin_unlock_irq_rcu_node(ssp->srcu_sup);
 
        if (pushgp)
                queue_delayed_work(rcu_gp_wq, &ssp->work, delay);