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tcp: md5: do not use alloc_percpu() 

percpu tcp_md5sig_pool contains memory blobs that ultimately
go through sg_set_buf().

-> sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));

This requires that whole area is in a physically contiguous portion
of memory. And that @buf is not backed by vmalloc().

Given that alloc_percpu() can use vmalloc() areas, this does not
fit the requirements.

Replace alloc_percpu() by a static DEFINE_PER_CPU() as tcp_md5sig_pool
is small anyway, there is no gain to dynamically allocate it.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 765cf9976e ("tcp: md5: remove one indirection level in tcp_md5sig_pool")
Reported-by: Crestez Dan Leonard <cdleonard@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-10-23 12:58:58 -07:00 committed by David S. Miller
parent 4cc40af080
commit 349ce993ac
1 changed files with 20 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
net/ipv4/tcp.c
View File

@ -2868,61 +2868,42 @@ EXPORT_SYMBOL(compat_tcp_getsockopt);
#endif
#ifdef CONFIG_TCP_MD5SIG
static struct tcp_md5sig_pool __percpu *tcp_md5sig_pool __read_mostly;
static DEFINE_PER_CPU(struct tcp_md5sig_pool, tcp_md5sig_pool);
static DEFINE_MUTEX(tcp_md5sig_mutex);
static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool __percpu *pool)
{
int cpu;
for_each_possible_cpu(cpu) {
struct tcp_md5sig_pool *p = per_cpu_ptr(pool, cpu);
if (p->md5_desc.tfm)
crypto_free_hash(p->md5_desc.tfm);
}
free_percpu(pool);
}
static bool tcp_md5sig_pool_populated = false;
static void __tcp_alloc_md5sig_pool(void)
{
int cpu;
struct tcp_md5sig_pool __percpu *pool;
pool = alloc_percpu(struct tcp_md5sig_pool);
if (!pool)
return;
for_each_possible_cpu(cpu) {
struct crypto_hash *hash;
if (!per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm) {
struct crypto_hash *hash;
hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR_OR_NULL(hash))
goto out_free;
per_cpu_ptr(pool, cpu)->md5_desc.tfm = hash;
hash = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR_OR_NULL(hash))
return;
per_cpu(tcp_md5sig_pool, cpu).md5_desc.tfm = hash;
}
}
/* before setting tcp_md5sig_pool, we must commit all writes
* to memory. See ACCESS_ONCE() in tcp_get_md5sig_pool()
/* before setting tcp_md5sig_pool_populated, we must commit all writes
* to memory. See smp_rmb() in tcp_get_md5sig_pool()
*/
smp_wmb();
tcp_md5sig_pool = pool;
return;
out_free:
__tcp_free_md5sig_pool(pool);
tcp_md5sig_pool_populated = true;
}
bool tcp_alloc_md5sig_pool(void)
{
if (unlikely(!tcp_md5sig_pool)) {
if (unlikely(!tcp_md5sig_pool_populated)) {
mutex_lock(&tcp_md5sig_mutex);
if (!tcp_md5sig_pool)
if (!tcp_md5sig_pool_populated)
__tcp_alloc_md5sig_pool();
mutex_unlock(&tcp_md5sig_mutex);
}
return tcp_md5sig_pool != NULL;
return tcp_md5sig_pool_populated;
}
EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
@ -2936,13 +2917,13 @@ EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
*/
struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
{
struct tcp_md5sig_pool __percpu *p;
local_bh_disable();
p = ACCESS_ONCE(tcp_md5sig_pool);
if (p)
return raw_cpu_ptr(p);
if (tcp_md5sig_pool_populated) {
/* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
smp_rmb();
return this_cpu_ptr(&tcp_md5sig_pool);
}
local_bh_enable();
return NULL;
}