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authorEric Dumazet <edumazet@google.com>2015-04-25 09:35:24 -0700
committerDavid S. Miller <davem@davemloft.net>2015-04-26 16:07:57 -0400
commita31196b07f8034eba6a3487a1ad1bb5ec5cd58a5 (patch)
tree7f870304863599f718850712a8c02e51359f0897 /net
parent7cdbc6f74f8e6c06304b69b4e944fbd669581c7c (diff)
downloadkernel-a31196b07f8034eba6a3487a1ad1bb5ec5cd58a5.tar.gz
net: rfs: fix crash in get_rps_cpus()
Commit 567e4b79731c ("net: rfs: add hash collision detection") had one mistake : RPS_NO_CPU is no longer the marker for invalid cpu in set_rps_cpu() and get_rps_cpu(), as @next_cpu was the result of an AND with rps_cpu_mask This bug showed up on a host with 72 cpus : next_cpu was 0x7f, and the code was trying to access percpu data of an non existent cpu. In a follow up patch, we might get rid of compares against nr_cpu_ids, if we init the tables with 0. This is silly to test for a very unlikely condition that exists only shortly after table initialization, as we got rid of rps_reset_sock_flow() and similar functions that were writing this RPS_NO_CPU magic value at flow dismantle : When table is old enough, it never contains this value anymore. Fixes: 567e4b79731c ("net: rfs: add hash collision detection") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Tom Herbert <tom@herbertland.com> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 1796cef55ab5..c7ba0388f1be 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3079,7 +3079,7 @@ static struct rps_dev_flow *
set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
struct rps_dev_flow *rflow, u16 next_cpu)
{
- if (next_cpu != RPS_NO_CPU) {
+ if (next_cpu < nr_cpu_ids) {
#ifdef CONFIG_RFS_ACCEL
struct netdev_rx_queue *rxqueue;
struct rps_dev_flow_table *flow_table;
@@ -3184,7 +3184,7 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
* If the desired CPU (where last recvmsg was done) is
* different from current CPU (one in the rx-queue flow
* table entry), switch if one of the following holds:
- * - Current CPU is unset (equal to RPS_NO_CPU).
+ * - Current CPU is unset (>= nr_cpu_ids).
* - Current CPU is offline.
* - The current CPU's queue tail has advanced beyond the
* last packet that was enqueued using this table entry.
@@ -3192,14 +3192,14 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
* have been dequeued, thus preserving in order delivery.
*/
if (unlikely(tcpu != next_cpu) &&
- (tcpu == RPS_NO_CPU || !cpu_online(tcpu) ||
+ (tcpu >= nr_cpu_ids || !cpu_online(tcpu) ||
((int)(per_cpu(softnet_data, tcpu).input_queue_head -
rflow->last_qtail)) >= 0)) {
tcpu = next_cpu;
rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
}
- if (tcpu != RPS_NO_CPU && cpu_online(tcpu)) {
+ if (tcpu < nr_cpu_ids && cpu_online(tcpu)) {
*rflowp = rflow;
cpu = tcpu;
goto done;
@@ -3240,14 +3240,14 @@ bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index,
struct rps_dev_flow_table *flow_table;
struct rps_dev_flow *rflow;
bool expire = true;
- int cpu;
+ unsigned int cpu;
rcu_read_lock();
flow_table = rcu_dereference(rxqueue->rps_flow_table);
if (flow_table && flow_id <= flow_table->mask) {
rflow = &flow_table->flows[flow_id];
cpu = ACCESS_ONCE(rflow->cpu);
- if (rflow->filter == filter_id && cpu != RPS_NO_CPU &&
+ if (rflow->filter == filter_id && cpu < nr_cpu_ids &&
((int)(per_cpu(softnet_data, cpu).input_queue_head -
rflow->last_qtail) <
(int)(10 * flow_table->mask)))