[PATCH 2/2] pptp: Reset call_id as 0 to avoid one useless lookup at next time
From: <hidden>
Date: 2016-08-18 05:08:18
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Gao Feng <redacted> When pptp fails to get valid callid, the global call_id is set as MAX_CALLID. Then it must fail to get callid at next time, when invoke find_next_zero_bit from call_id+1. Because the call_id+1 exceeds the limit "MAX_CALLID". So reset call_id as 0 when fail to get valid callid. And add one variable to check if need the second lookup. Signed-off-by: Gao Feng <redacted> --- v1: Initial patch drivers/net/ppp/pptp.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index 48c3701..9afef3c 100644
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c@@ -103,12 +103,21 @@ static int add_chan(struct pppox_sock *sock, static int call_id; spin_lock(&chan_lock); - if (!sa->call_id) { + if (!sa->call_id) { + bool from_start = (call_id == 0); + call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, call_id + 1); if (call_id == MAX_CALLID) { - call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1); - if (call_id == MAX_CALLID) + if (unlikely(from_start)) { + call_id = 0; goto out_err; + } else { + call_id = find_next_zero_bit(callid_bitmap, MAX_CALLID, 1); + if (call_id == MAX_CALLID) { + call_id = 0; + goto out_err; + } + } } sa->call_id = call_id; } else if (test_bit(sa->call_id, callid_bitmap)) {
@@ -656,8 +665,10 @@ static int __init pptp_init_module(void) pr_info("PPTP driver version " PPTP_DRIVER_VERSION "\n"); callid_sock = vzalloc((MAX_CALLID + 1) * sizeof(void *)); - if (!callid_sock) + if (!callid_sock) { + pr_err("PPTP: can't alloc callid_sock mem"); return -ENOMEM; + } err = gre_add_protocol(&gre_pptp_protocol, GREPROTO_PPTP); if (err) {
--
1.9.1