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Message-ID: <1432652134.4060.244.camel@edumazet-glaptop2.roam.corp.google.com>
Date: Tue, 26 May 2015 07:55:34 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] tcp: fix/cleanup inet_ehash_locks_alloc()
From: Eric Dumazet <edumazet@...gle.com>
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@...gle.com>
---
include/net/inet_hashtables.h | 47 ++------------------------------
net/ipv4/inet_hashtables.c | 31 +++++++++++++++++++++
2 files changed, 34 insertions(+), 44 deletions(-)
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 774d24151d4a..b73c88a19dd4 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -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 *
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 3766bddb3e8a..185efef0f125 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -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);
--
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