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Koen Kooi
df83a59b6b
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net> Signed-off-by: Denys Dmytriyenko <denys@ti.com>
94 lines
3.1 KiB
Diff
94 lines
3.1 KiB
Diff
From e056f9e8a25db637798455e701c2a42f9cdeb5b8 Mon Sep 17 00:00:00 2001
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From: Neil Horman <nhorman@tuxdriver.com>
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Date: Tue, 1 May 2012 08:18:02 +0000
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Subject: [PATCH 65/70] drop_monitor: prevent init path from scheduling on the
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wrong cpu
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commit 4fdcfa12843bca38d0c9deff70c8720e4e8f515f upstream.
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I just noticed after some recent updates, that the init path for the drop
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monitor protocol has a minor error. drop monitor maintains a per cpu structure,
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that gets initalized from a single cpu. Normally this is fine, as the protocol
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isn't in use yet, but I recently made a change that causes a failed skb
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allocation to reschedule itself . Given the current code, the implication is
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that this workqueue reschedule will take place on the wrong cpu. If drop
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monitor is used early during the boot process, its possible that two cpus will
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access a single per-cpu structure in parallel, possibly leading to data
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corruption.
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This patch fixes the situation, by storing the cpu number that a given instance
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of this per-cpu data should be accessed from. In the case of a need for a
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reschedule, the cpu stored in the struct is assigned the rescheule, rather than
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the currently executing cpu
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Tested successfully by myself.
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Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
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CC: David Miller <davem@davemloft.net>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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---
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net/core/drop_monitor.c | 12 +++++++-----
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1 files changed, 7 insertions(+), 5 deletions(-)
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diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
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index d75cbfc..e836592 100644
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--- a/net/core/drop_monitor.c
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+++ b/net/core/drop_monitor.c
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@@ -49,6 +49,7 @@ struct per_cpu_dm_data {
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struct sk_buff __rcu *skb;
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atomic_t dm_hit_count;
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struct timer_list send_timer;
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+ int cpu;
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};
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struct dm_hw_stat_delta {
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@@ -73,7 +74,6 @@ static int dm_hit_limit = 64;
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static int dm_delay = 1;
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static unsigned long dm_hw_check_delta = 2*HZ;
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static LIST_HEAD(hw_stats_list);
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-static int initialized = 0;
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static void reset_per_cpu_data(struct per_cpu_dm_data *data)
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{
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@@ -96,8 +96,8 @@ static void reset_per_cpu_data(struct per_cpu_dm_data *data)
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sizeof(struct net_dm_alert_msg));
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msg = nla_data(nla);
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memset(msg, 0, al);
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- } else if (initialized)
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- schedule_work_on(smp_processor_id(), &data->dm_alert_work);
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+ } else
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+ schedule_work_on(data->cpu, &data->dm_alert_work);
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/*
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* Don't need to lock this, since we are guaranteed to only
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@@ -121,6 +121,8 @@ static void send_dm_alert(struct work_struct *unused)
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struct sk_buff *skb;
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struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
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+ WARN_ON_ONCE(data->cpu != smp_processor_id());
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+
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/*
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* Grab the skb we're about to send
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*/
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@@ -403,14 +405,14 @@ static int __init init_net_drop_monitor(void)
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for_each_present_cpu(cpu) {
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data = &per_cpu(dm_cpu_data, cpu);
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- reset_per_cpu_data(data);
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+ data->cpu = cpu;
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INIT_WORK(&data->dm_alert_work, send_dm_alert);
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init_timer(&data->send_timer);
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data->send_timer.data = cpu;
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data->send_timer.function = sched_send_work;
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+ reset_per_cpu_data(data);
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}
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- initialized = 1;
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goto out;
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--
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1.7.7.6
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