netdev - [PATCH] drop_monitor: allow more events per second

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <1334855781.2395.203.camel@edumazet-glaptop>
Date:	Thu, 19 Apr 2012 19:16:21 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Neil Horman <nhorman@...driver.com>,
	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>
Subject: [PATCH] drop_monitor: allow more events per second

From: Eric Dumazet <edumazet@...gle.com>

It seems there is a logic error in trace_drop_common(), since we store
only 64 drops, even if they are from same location.

This fix is a one liner, but we probably need more work to avoid useless
atomic dec/inc

Now I can watch 1 Mpps drops through dropwatch...

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Neil Horman <nhorman@...driver.com>
---
Neil, it seems this code is not SMP/preempt safe. Worker can free our
data under us, and genlmsg_new() can return NULL under stress.

 net/core/drop_monitor.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 7f36b38..5c3c81a 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -150,6 +150,7 @@ static void trace_drop_common(struct sk_buff *skb, void *location)
 	for (i = 0; i < msg->entries; i++) {
 		if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
 			msg->points[i].count++;
+			atomic_inc(&data->dm_hit_count);
 			goto out;
 		}
 	}


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html