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Subject[051/146] inetpeer: reduce stack usage
2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------


From: Eric Dumazet <eric.dumazet@gmail.com>

[ Upstream commit 66944e1c5797562cebe2d1857d46dff60bf9a69e ]

On 64bit arches, we use 752 bytes of stack when cleanup_once() is called
from inet_getpeer().

Lets share the avl stack to save ~376 bytes.

Before patch :

# objdump -d net/ipv4/inetpeer.o | scripts/checkstack.pl

0x000006c3 unlink_from_pool [inetpeer.o]: 376
0x00000721 unlink_from_pool [inetpeer.o]: 376
0x00000cb1 inet_getpeer [inetpeer.o]: 376
0x00000e6d inet_getpeer [inetpeer.o]: 376
0x0004 inet_initpeers [inetpeer.o]: 112
# size net/ipv4/inetpeer.o
text data bss dec hex filename
5320 432 21 5773 168d net/ipv4/inetpeer.o

After patch :

objdump -d net/ipv4/inetpeer.o | scripts/checkstack.pl
0x00000c11 inet_getpeer [inetpeer.o]: 376
0x00000dcd inet_getpeer [inetpeer.o]: 376
0x00000ab9 peer_check_expire [inetpeer.o]: 328
0x00000b7f peer_check_expire [inetpeer.o]: 328
0x0004 inet_initpeers [inetpeer.o]: 112
# size net/ipv4/inetpeer.o
text data bss dec hex filename
5163 432 21 5616 15f0 net/ipv4/inetpeer.o

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Scot Doyle <lkml@scotdoyle.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Reviewed-by: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
net/ipv4/inetpeer.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -366,7 +366,8 @@ static void inetpeer_free_rcu(struct rcu
}

/* May be called with local BH enabled. */
-static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base)
+static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base,
+ struct inet_peer __rcu **stack[PEER_MAXDEPTH])
{
int do_free;

@@ -380,7 +381,6 @@ static void unlink_from_pool(struct inet
* We use refcnt=-1 to alert lockless readers this entry is deleted.
*/
if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) {
- struct inet_peer __rcu **stack[PEER_MAXDEPTH];
struct inet_peer __rcu ***stackptr, ***delp;
if (lookup(&p->daddr, stack, base) != p)
BUG();
@@ -435,7 +435,7 @@ static struct inet_peer_base *peer_to_ba
}

/* May be called with local BH enabled. */
-static int cleanup_once(unsigned long ttl)
+static int cleanup_once(unsigned long ttl, struct inet_peer __rcu **stack[PEER_MAXDEPTH])
{
struct inet_peer *p = NULL;

@@ -467,7 +467,7 @@ static int cleanup_once(unsigned long tt
* happen because of entry limits in route cache. */
return -1;

- unlink_from_pool(p, peer_to_base(p));
+ unlink_from_pool(p, peer_to_base(p), stack);
return 0;
}

@@ -523,7 +523,7 @@ struct inet_peer *inet_getpeer(struct in

if (base->total >= inet_peer_threshold)
/* Remove one less-recently-used entry. */
- cleanup_once(0);
+ cleanup_once(0, stack);

return p;
}
@@ -539,6 +539,7 @@ static void peer_check_expire(unsigned l
{
unsigned long now = jiffies;
int ttl, total;
+ struct inet_peer __rcu **stack[PEER_MAXDEPTH];

total = compute_total();
if (total >= inet_peer_threshold)
@@ -547,7 +548,7 @@ static void peer_check_expire(unsigned l
ttl = inet_peer_maxttl
- (inet_peer_maxttl - inet_peer_minttl) / HZ *
total / inet_peer_threshold * HZ;
- while (!cleanup_once(ttl)) {
+ while (!cleanup_once(ttl, stack)) {
if (jiffies != now)
break;
}



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