AuxXxilium/linux_dsm_epyc7002
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inetpeer: Don't disable BH for initial fast RCU lookup.

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If modifications on other cpus are ok, then modifications to
the tree during lookup done by the local cpu are ok too.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2011-03-08 14:59:28 -08:00
parent 5217e87946
commit 7b46ac4e77
1 changed files with 9 additions and 9 deletions

18
net/ipv4/inetpeer.c
View File

@ -206,16 +206,16 @@ static int addr_compare(const struct inetpeer_addr *a,
}) })
/* /*
* Called with rcu_read_lock_bh() * Called with rcu_read_lock()
* Because we hold no lock against a writer, its quite possible we fall * Because we hold no lock against a writer, its quite possible we fall
* in an endless loop. * in an endless loop.
* But every pointer we follow is guaranteed to be valid thanks to RCU. * But every pointer we follow is guaranteed to be valid thanks to RCU.
* We exit from this function if number of links exceeds PEER_MAXDEPTH * We exit from this function if number of links exceeds PEER_MAXDEPTH
*/ */
static struct inet_peer *lookup_rcu_bh(const struct inetpeer_addr *daddr, static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr,
struct inet_peer_base *base) struct inet_peer_base *base)
{ {
struct inet_peer *u = rcu_dereference_bh(base->root); struct inet_peer *u = rcu_dereference(base->root);
int count = 0; int count = 0;
while (u != peer_avl_empty) { while (u != peer_avl_empty) {
@ -231,9 +231,9 @@ static struct inet_peer *lookup_rcu_bh(const struct inetpeer_addr *daddr,
return u; return u;
} }
if (cmp == -1) if (cmp == -1)
u = rcu_dereference_bh(u->avl_left); u = rcu_dereference(u->avl_left);
else else
u = rcu_dereference_bh(u->avl_right); u = rcu_dereference(u->avl_right);
if (unlikely(++count == PEER_MAXDEPTH)) if (unlikely(++count == PEER_MAXDEPTH))
break; break;
} }
@ -470,11 +470,11 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create)
/* Look up for the address quickly, lockless. /* Look up for the address quickly, lockless.
* Because of a concurrent writer, we might not find an existing entry. * Because of a concurrent writer, we might not find an existing entry.
*/ */
rcu_read_lock_bh(); rcu_read_lock();
sequence = read_seqbegin(&base->lock); sequence = read_seqbegin(&base->lock);
p = lookup_rcu_bh(daddr, base); p = lookup_rcu(daddr, base);
invalidated = read_seqretry(&base->lock, sequence); invalidated = read_seqretry(&base->lock, sequence);
rcu_read_unlock_bh(); rcu_read_unlock();
if (p) { if (p) {
/* The existing node has been found. /* The existing node has been found.