[PATCH] IPV4 : Move ip route cache flush (secret_rebuild) from softirq to workqueue
Every 600 seconds (ip_rt_secret_interval), a softirq flush of the
whole ip route cache is triggered. On loaded machines, this can starve
softirq for many seconds and can eventually crash.
This patch moves this flush to a workqueue context, using the worker
we intoduced in commit 39c90ece75
(IPV4:
Convert rt_check_expire() from softirq processing to workqueue.)
Also, immediate flushes (echo 0 >/proc/sys/net/ipv4/route/flush) are
using rt_do_flush() helper function, wich take attention to
rescheduling.
Next step will be to handle delayed flushes
("echo -1 >/proc/sys/net/ipv4/route/flush" or "ip route flush cache")
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
42a73808ed
commit
beb659bd8c
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@ -133,13 +133,14 @@ static int ip_rt_mtu_expires = 10 * 60 * HZ;
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static int ip_rt_min_pmtu = 512 + 20 + 20;
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static int ip_rt_min_advmss = 256;
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static int ip_rt_secret_interval = 10 * 60 * HZ;
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static int ip_rt_flush_expected;
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static unsigned long rt_deadline;
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#define RTprint(a...) printk(KERN_DEBUG a)
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static struct timer_list rt_flush_timer;
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static void rt_check_expire(struct work_struct *work);
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static DECLARE_DELAYED_WORK(expires_work, rt_check_expire);
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static void rt_worker_func(struct work_struct *work);
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static DECLARE_DELAYED_WORK(expires_work, rt_worker_func);
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static struct timer_list rt_secret_timer;
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/*
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@ -561,7 +562,36 @@ static inline int compare_keys(struct flowi *fl1, struct flowi *fl2)
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(fl1->iif ^ fl2->iif)) == 0;
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}
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static void rt_check_expire(struct work_struct *work)
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/*
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* Perform a full scan of hash table and free all entries.
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* Can be called by a softirq or a process.
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* In the later case, we want to be reschedule if necessary
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*/
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static void rt_do_flush(int process_context)
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{
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unsigned int i;
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struct rtable *rth, *next;
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for (i = 0; i <= rt_hash_mask; i++) {
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if (process_context && need_resched())
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cond_resched();
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rth = rt_hash_table[i].chain;
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if (!rth)
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continue;
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spin_lock_bh(rt_hash_lock_addr(i));
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rth = rt_hash_table[i].chain;
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rt_hash_table[i].chain = NULL;
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spin_unlock_bh(rt_hash_lock_addr(i));
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for (; rth; rth = next) {
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next = rth->u.dst.rt_next;
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rt_free(rth);
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}
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}
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}
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static void rt_check_expire(void)
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{
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static unsigned int rover;
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unsigned int i = rover, goal;
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@ -607,33 +637,33 @@ static void rt_check_expire(struct work_struct *work)
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spin_unlock_bh(rt_hash_lock_addr(i));
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}
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rover = i;
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}
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/*
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* rt_worker_func() is run in process context.
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* If a whole flush was scheduled, it is done.
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* Else, we call rt_check_expire() to scan part of the hash table
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*/
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static void rt_worker_func(struct work_struct *work)
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{
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if (ip_rt_flush_expected) {
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ip_rt_flush_expected = 0;
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rt_do_flush(1);
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} else
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rt_check_expire();
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schedule_delayed_work(&expires_work, ip_rt_gc_interval);
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}
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/* This can run from both BH and non-BH contexts, the latter
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* in the case of a forced flush event.
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*/
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static void rt_run_flush(unsigned long dummy)
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static void rt_run_flush(unsigned long process_context)
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{
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int i;
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struct rtable *rth, *next;
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rt_deadline = 0;
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get_random_bytes(&rt_hash_rnd, 4);
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for (i = rt_hash_mask; i >= 0; i--) {
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spin_lock_bh(rt_hash_lock_addr(i));
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rth = rt_hash_table[i].chain;
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if (rth)
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rt_hash_table[i].chain = NULL;
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spin_unlock_bh(rt_hash_lock_addr(i));
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for (; rth; rth = next) {
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next = rth->u.dst.rt_next;
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rt_free(rth);
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}
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}
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rt_do_flush(process_context);
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}
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static DEFINE_SPINLOCK(rt_flush_lock);
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@ -667,7 +697,7 @@ void rt_cache_flush(int delay)
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if (delay <= 0) {
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spin_unlock_bh(&rt_flush_lock);
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rt_run_flush(0);
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rt_run_flush(user_mode);
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return;
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}
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@ -678,12 +708,17 @@ void rt_cache_flush(int delay)
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spin_unlock_bh(&rt_flush_lock);
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}
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/*
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* We change rt_hash_rnd and ask next rt_worker_func() invocation
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* to perform a flush in process context
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*/
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static void rt_secret_rebuild(unsigned long dummy)
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{
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unsigned long now = jiffies;
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rt_cache_flush(0);
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mod_timer(&rt_secret_timer, now + ip_rt_secret_interval);
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get_random_bytes(&rt_hash_rnd, 4);
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ip_rt_flush_expected = 1;
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cancel_delayed_work(&expires_work);
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schedule_delayed_work(&expires_work, HZ/10);
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mod_timer(&rt_secret_timer, jiffies + ip_rt_secret_interval);
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}
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/*
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