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tcp: fix/cleanup inet_ehash_locks_alloc() 

If tcp ehash table is constrained to a very small number of buckets
(eg boot parameter thash_entries=128), then we can crash if spinlock
array has more entries.

While we are at it, un-inline inet_ehash_locks_alloc() and make
following changes :

- Budget 2 cache lines per cpu worth of 'spinlocks'
- Try to kmalloc() the array to avoid extra TLB pressure.
  (Most servers at Google allocate 8192 bytes for this hash table)
- Get rid of various #ifdef

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2015-05-26 07:55:34 -07:00 committed by David S. Miller
parent f3903bcc00
commit 095dc8e0c3
2 changed files with 34 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

47
include/net/inet_hashtables.h
View File

@ -24,7 +24,6 @@
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/vmalloc.h>
#include <net/inet_connection_sock.h>
#include <net/inet_sock.h>
@ -164,52 +163,12 @@ static inline spinlock_t *inet_ehash_lockp(
return &hashinfo->ehash_locks[hash & hashinfo->ehash_locks_mask];
}
static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
{
unsigned int i, size = 256;
#if defined(CONFIG_PROVE_LOCKING)
unsigned int nr_pcpus = 2;
#else
unsigned int nr_pcpus = num_possible_cpus();
#endif
if (nr_pcpus >= 4)
size = 512;
if (nr_pcpus >= 8)
size = 1024;
if (nr_pcpus >= 16)
size = 2048;
if (nr_pcpus >= 32)
size = 4096;
if (sizeof(spinlock_t) != 0) {
#ifdef CONFIG_NUMA
if (size * sizeof(spinlock_t) > PAGE_SIZE)
hashinfo->ehash_locks = vmalloc(size * sizeof(spinlock_t));
else
#endif
hashinfo->ehash_locks = kmalloc(size * sizeof(spinlock_t),
GFP_KERNEL);
if (!hashinfo->ehash_locks)
return ENOMEM;
for (i = 0; i < size; i++)
spin_lock_init(&hashinfo->ehash_locks[i]);
}
hashinfo->ehash_locks_mask = size - 1;
return 0;
}
int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo);
static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
{
if (hashinfo->ehash_locks) {
#ifdef CONFIG_NUMA
unsigned int size = (hashinfo->ehash_locks_mask + 1) *
sizeof(spinlock_t);
if (size > PAGE_SIZE)
vfree(hashinfo->ehash_locks);
else
#endif
kfree(hashinfo->ehash_locks);
hashinfo->ehash_locks = NULL;
}
kvfree(hashinfo->ehash_locks);
hashinfo->ehash_locks = NULL;
}
struct inet_bind_bucket *

31
net/ipv4/inet_hashtables.c
View File

@ -18,6 +18,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/vmalloc.h>
#include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h>
@ -609,3 +610,33 @@ void inet_hashinfo_init(struct inet_hashinfo *h)
}
}
EXPORT_SYMBOL_GPL(inet_hashinfo_init);
int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
{
unsigned int i, nblocks = 1;
if (sizeof(spinlock_t) != 0) {
/* allocate 2 cache lines or at least one spinlock per cpu */
nblocks = max_t(unsigned int,
2 * L1_CACHE_BYTES / sizeof(spinlock_t),
1);
nblocks = roundup_pow_of_two(nblocks * num_possible_cpus());
/* no more locks than number of hash buckets */
nblocks = min(nblocks, hashinfo->ehash_mask + 1);
hashinfo->ehash_locks = kmalloc_array(nblocks, sizeof(spinlock_t),
GFP_KERNEL | __GFP_NOWARN);
if (!hashinfo->ehash_locks)
hashinfo->ehash_locks = vmalloc(nblocks * sizeof(spinlock_t));
if (!hashinfo->ehash_locks)
return -ENOMEM;
for (i = 0; i < nblocks; i++)
spin_lock_init(&hashinfo->ehash_locks[i]);
}
hashinfo->ehash_locks_mask = nblocks - 1;
return 0;
}
EXPORT_SYMBOL_GPL(inet_ehash_locks_alloc);