path: root/Documentation
diff options
authorEric Dumazet <>2015-04-25 09:35:24 -0700
committerDavid S. Miller <>2015-04-26 16:07:57 -0400
commita31196b07f8034eba6a3487a1ad1bb5ec5cd58a5 (patch)
tree7f870304863599f718850712a8c02e51359f0897 /Documentation
parent7cdbc6f74f8e6c06304b69b4e944fbd669581c7c (diff)
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 <> Cc: Tom Herbert <> Cc: Ben Hutchings <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'Documentation')
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/networking/scaling.txt b/Documentation/networking/scaling.txt
index cbfac0949635..59f4db2a0c85 100644
--- a/Documentation/networking/scaling.txt
+++ b/Documentation/networking/scaling.txt
@@ -282,7 +282,7 @@ following is true:
- The current CPU's queue head counter >= the recorded tail counter
value in rps_dev_flow[i]
-- The current CPU is unset (equal to RPS_NO_CPU)
+- The current CPU is unset (>= nr_cpu_ids)
- The current CPU is offline
After this check, the packet is sent to the (possibly updated) current