flow: structurize flow cache

Group all per-cpu data to one structure instead of having many
globals. Also prepare the internals so that we can have multiple
instances of the flow cache if needed.

Only the kmem_cache is left as a global as all flow caches share
the same element size, and benefit from using a common cache.

Signed-off-by: Timo Teras <timo.teras@iki.fi>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 119 insertions, 104 deletions

diff --git a/net/core/flow.c b/net/core/flow.c
index 96015871ecea..1d27ca6b421d 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -35,104 +35,105 @@ struct flow_cache_entry {
         atomic_t                *object_ref;
 };
 
-atomic_t flow_cache_genid = ATOMIC_INIT(0);
-
-static u32 flow_hash_shift;
-#define flow_hash_size  (1 << flow_hash_shift)
-static DEFINE_PER_CPU(struct flow_cache_entry **, flow_tables) = { NULL };
-
-#define flow_table(cpu) (per_cpu(flow_tables, cpu))
-
-static struct kmem_cache *flow_cachep __read_mostly;
-
-static int flow_lwm, flow_hwm;
-
-struct flow_percpu_info {
-        int hash_rnd_recalc;
-        u32 hash_rnd;
-        int count;
+struct flow_cache_percpu {
+        struct flow_cache_entry **      hash_table;
+        int                             hash_count;
+        u32                             hash_rnd;
+        int                             hash_rnd_recalc;
+        struct tasklet_struct           flush_tasklet;
 };
-static DEFINE_PER_CPU(struct flow_percpu_info, flow_hash_info) = { 0 };
-
-#define flow_hash_rnd_recalc(cpu) \
-        (per_cpu(flow_hash_info, cpu).hash_rnd_recalc)
-#define flow_hash_rnd(cpu) \
-        (per_cpu(flow_hash_info, cpu).hash_rnd)
-#define flow_count(cpu) \
-        (per_cpu(flow_hash_info, cpu).count)
-
-static struct timer_list flow_hash_rnd_timer;
-
-#define FLOW_HASH_RND_PERIOD    (10 * 60 * HZ)
 
 struct flow_flush_info {
-        atomic_t cpuleft;
-        struct completion completion;
+        struct flow_cache *             cache;
+        atomic_t                        cpuleft;
+        struct completion               completion;
 };
-static DEFINE_PER_CPU(struct tasklet_struct, flow_flush_tasklets) = { NULL };
 
-#define flow_flush_tasklet(cpu) (&per_cpu(flow_flush_tasklets, cpu))
+struct flow_cache {
+        u32                             hash_shift;
+        unsigned long                   order;
+        struct flow_cache_percpu *      percpu;
+        struct notifier_block           hotcpu_notifier;
+        int                             low_watermark;
+        int                             high_watermark;
+        struct timer_list               rnd_timer;
+};
+
+atomic_t flow_cache_genid = ATOMIC_INIT(0);
+static struct flow_cache flow_cache_global;
+static struct kmem_cache *flow_cachep;
+
+#define flow_cache_hash_size(cache)     (1 << (cache)->hash_shift)
+#define FLOW_HASH_RND_PERIOD            (10 * 60 * HZ)
 
 static void flow_cache_new_hashrnd(unsigned long arg)
 {
+        struct flow_cache *fc = (void *) arg;
         int i;
 
         for_each_possible_cpu(i)
-                flow_hash_rnd_recalc(i) = 1;
+                per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
 
-        flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
-        add_timer(&flow_hash_rnd_timer);
+        fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+        add_timer(&fc->rnd_timer);
 }
 
-static void flow_entry_kill(int cpu, struct flow_cache_entry *fle)
+static void flow_entry_kill(struct flow_cache *fc,
+                            struct flow_cache_percpu *fcp,
+                            struct flow_cache_entry *fle)
 {
         if (fle->object)
                 atomic_dec(fle->object_ref);
         kmem_cache_free(flow_cachep, fle);
-        flow_count(cpu)--;
+        fcp->hash_count--;
 }
 
-static void __flow_cache_shrink(int cpu, int shrink_to)
+static void __flow_cache_shrink(struct flow_cache *fc,
+                                struct flow_cache_percpu *fcp,
+                                int shrink_to)
 {
         struct flow_cache_entry *fle, **flp;
         int i;
 
-        for (i = 0; i < flow_hash_size; i++) {
+        for (i = 0; i < flow_cache_hash_size(fc); i++) {
                 int k = 0;
 
-                flp = &flow_table(cpu)[i];
+                flp = &fcp->hash_table[i];
                 while ((fle = *flp) != NULL && k < shrink_to) {
                         k++;
                         flp = &fle->next;
                 }
                 while ((fle = *flp) != NULL) {
                         *flp = fle->next;
-                        flow_entry_kill(cpu, fle);
+                        flow_entry_kill(fc, fcp, fle);
                 }
         }
 }
 
-static void flow_cache_shrink(int cpu)
+static void flow_cache_shrink(struct flow_cache *fc,
+                              struct flow_cache_percpu *fcp)
 {
-        int shrink_to = flow_lwm / flow_hash_size;
+        int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
 
-        __flow_cache_shrink(cpu, shrink_to);
+        __flow_cache_shrink(fc, fcp, shrink_to);
 }
 
-static void flow_new_hash_rnd(int cpu)
+static void flow_new_hash_rnd(struct flow_cache *fc,
+                              struct flow_cache_percpu *fcp)
 {
-        get_random_bytes(&flow_hash_rnd(cpu), sizeof(u32));
-        flow_hash_rnd_recalc(cpu) = 0;
-
-        __flow_cache_shrink(cpu, 0);
+        get_random_bytes(&fcp->hash_rnd, sizeof(u32));
+        fcp->hash_rnd_recalc = 0;
+        __flow_cache_shrink(fc, fcp, 0);
 }
 
-static u32 flow_hash_code(struct flowi *key, int cpu)
+static u32 flow_hash_code(struct flow_cache *fc,
+                          struct flow_cache_percpu *fcp,
+                          struct flowi *key)
 {
         u32 *k = (u32 *) key;
 
-        return (jhash2(k, (sizeof(*key) / sizeof(u32)), flow_hash_rnd(cpu)) &
-                (flow_hash_size - 1));
+        return (jhash2(k, (sizeof(*key) / sizeof(u32)), fcp->hash_rnd)
+                & (flow_cache_hash_size(fc) - 1));
 }
 
 #if (BITS_PER_LONG == 64)
@@ -168,24 +169,25 @@ static int flow_key_compare(struct flowi *key1, struct flowi *key2)
 void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
                         flow_resolve_t resolver)
 {
+        struct flow_cache *fc = &flow_cache_global;
+        struct flow_cache_percpu *fcp;
         struct flow_cache_entry *fle, **head;
         unsigned int hash;
-        int cpu;
 
         local_bh_disable();
-        cpu = smp_processor_id();
+        fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
 
         fle = NULL;
         /* Packet really early in init?  Making flow_cache_init a
          * pre-smp initcall would solve this.  --RR */
-        if (!flow_table(cpu))
+        if (!fcp->hash_table)
                 goto nocache;
 
-        if (flow_hash_rnd_recalc(cpu))
-                flow_new_hash_rnd(cpu);
-        hash = flow_hash_code(key, cpu);
+        if (fcp->hash_rnd_recalc)
+                flow_new_hash_rnd(fc, fcp);
+        hash = flow_hash_code(fc, fcp, key);
 
-        head = &flow_table(cpu)[hash];
+        head = &fcp->hash_table[hash];
         for (fle = *head; fle; fle = fle->next) {
                 if (fle->family == family &&
                     fle->dir == dir &&
@@ -204,8 +206,8 @@ void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
         }
 
         if (!fle) {
-                if (flow_count(cpu) > flow_hwm)
-                        flow_cache_shrink(cpu);
+                if (fcp->hash_count > fc->high_watermark)
+                        flow_cache_shrink(fc, fcp);
 
                 fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
                 if (fle) {
@@ -215,7 +217,7 @@ void *flow_cache_lookup(struct net *net, struct flowi *key, u16 family, u8 dir,
                         fle->dir = dir;
                         memcpy(&fle->key, key, sizeof(*key));
                         fle->object = NULL;
-                        flow_count(cpu)++;
+                        fcp->hash_count++;
                 }
         }
 
@@ -249,14 +251,15 @@ nocache:
 static void flow_cache_flush_tasklet(unsigned long data)
 {
         struct flow_flush_info *info = (void *)data;
+        struct flow_cache *fc = info->cache;
+        struct flow_cache_percpu *fcp;
         int i;
-        int cpu;
 
-        cpu = smp_processor_id();
-        for (i = 0; i < flow_hash_size; i++) {
+        fcp = per_cpu_ptr(fc->percpu, smp_processor_id());
+        for (i = 0; i < flow_cache_hash_size(fc); i++) {
                 struct flow_cache_entry *fle;
 
-                fle = flow_table(cpu)[i];
+                fle = fcp->hash_table[i];
                 for (; fle; fle = fle->next) {
                         unsigned genid = atomic_read(&flow_cache_genid);
 
@@ -272,7 +275,6 @@ static void flow_cache_flush_tasklet(unsigned long data)
                 complete(&info->completion);
 }
 
-static void flow_cache_flush_per_cpu(void *) __attribute__((__unused__));
 static void flow_cache_flush_per_cpu(void *data)
 {
         struct flow_flush_info *info = data;
@@ -280,8 +282,7 @@ static void flow_cache_flush_per_cpu(void *data)
         struct tasklet_struct *tasklet;
 
         cpu = smp_processor_id();
-
-        tasklet = flow_flush_tasklet(cpu);
+        tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
         tasklet->data = (unsigned long)info;
         tasklet_schedule(tasklet);
 }
@@ -294,6 +295,7 @@ void flow_cache_flush(void)
         /* Don't want cpus going down or up during this. */
         get_online_cpus();
         mutex_lock(&flow_flush_sem);
+        info.cache = &flow_cache_global;
         atomic_set(&info.cpuleft, num_online_cpus());
         init_completion(&info.completion);
 
@@ -307,62 +309,75 @@ void flow_cache_flush(void)
         put_online_cpus();
 }
 
-static void __init flow_cache_cpu_prepare(int cpu)
+static void __init flow_cache_cpu_prepare(struct flow_cache *fc,
+                                          struct flow_cache_percpu *fcp)
 {
-        struct tasklet_struct *tasklet;
-        unsigned long order;
-
-        for (order = 0;
-             (PAGE_SIZE << order) <
-                     (sizeof(struct flow_cache_entry *)*flow_hash_size);
-             order++)
-                /* NOTHING */;
-
-        flow_table(cpu) = (struct flow_cache_entry **)
-                __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
-        if (!flow_table(cpu))
-                panic("NET: failed to allocate flow cache order %lu\n", order);
-
-        flow_hash_rnd_recalc(cpu) = 1;
-        flow_count(cpu) = 0;
-
-        tasklet = flow_flush_tasklet(cpu);
-        tasklet_init(tasklet, flow_cache_flush_tasklet, 0);
+        fcp->hash_table = (struct flow_cache_entry **)
+                __get_free_pages(GFP_KERNEL|__GFP_ZERO, fc->order);
+        if (!fcp->hash_table)
+                panic("NET: failed to allocate flow cache order %lu\n", fc->order);
+
+        fcp->hash_rnd_recalc = 1;
+        fcp->hash_count = 0;
+        tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
 }
 
 static int flow_cache_cpu(struct notifier_block *nfb,
                           unsigned long action,
                           void *hcpu)
 {
+        struct flow_cache *fc = container_of(nfb, struct flow_cache, hotcpu_notifier);
+        int cpu = (unsigned long) hcpu;
+        struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
+
         if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
-                __flow_cache_shrink((unsigned long)hcpu, 0);
+                __flow_cache_shrink(fc, fcp, 0);
         return NOTIFY_OK;
 }
 
-static int __init flow_cache_init(void)
+static int flow_cache_init(struct flow_cache *fc)
 {
+        unsigned long order;
         int i;
 
-        flow_cachep = kmem_cache_create("flow_cache",
-                                        sizeof(struct flow_cache_entry),
-                                        0, SLAB_PANIC,
-                                        NULL);
-        flow_hash_shift = 10;
-        flow_lwm = 2 * flow_hash_size;
-        flow_hwm = 4 * flow_hash_size;
+        fc->hash_shift = 10;
+        fc->low_watermark = 2 * flow_cache_hash_size(fc);
+        fc->high_watermark = 4 * flow_cache_hash_size(fc);
+
+        for (order = 0;
+             (PAGE_SIZE << order) <
+                     (sizeof(struct flow_cache_entry *)*flow_cache_hash_size(fc));
+             order++)
+                /* NOTHING */;
+        fc->order = order;
+        fc->percpu = alloc_percpu(struct flow_cache_percpu);
 
-        setup_timer(&flow_hash_rnd_timer, flow_cache_new_hashrnd, 0);
-        flow_hash_rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
-        add_timer(&flow_hash_rnd_timer);
+        setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
+                    (unsigned long) fc);
+        fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
+        add_timer(&fc->rnd_timer);
 
         for_each_possible_cpu(i)
-                flow_cache_cpu_prepare(i);
+                flow_cache_cpu_prepare(fc, per_cpu_ptr(fc->percpu, i));
+
+        fc->hotcpu_notifier = (struct notifier_block){
+                .notifier_call = flow_cache_cpu,
+        };
+        register_hotcpu_notifier(&fc->hotcpu_notifier);
 
-        hotcpu_notifier(flow_cache_cpu, 0);
         return 0;
 }
 
-module_init(flow_cache_init);
+static int __init flow_cache_init_global(void)
+{
+        flow_cachep = kmem_cache_create("flow_cache",
+                                        sizeof(struct flow_cache_entry),
+                                        0, SLAB_PANIC, NULL);
+
+        return flow_cache_init(&flow_cache_global);
+}
+
+module_init(flow_cache_init_global);
 
 EXPORT_SYMBOL(flow_cache_genid);
 EXPORT_SYMBOL(flow_cache_lookup);