Eric Lee / smarc-ti-linux-kernel

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Commit 85328240c625f322af9f69c7b60e619717101d77

Authored by John Fastabend
Committed by Jeff Kirsher
1 parent 781069279f
Exists in master and in 16 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

net: allow netdev_all_upper_get_next_dev_rcu with rtnl lock held 

It is useful to be able to walk all upper devices when bringing
a device online where the RTNL lock is held. In this case it
is safe to walk the all_adj_list because the RTNL lock is used
to protect the write side as well.

This patch adds a check to see if the rtnl lock is held before
throwing a warning in netdev_all_upper_get_next_dev_rcu().

Also because we now have a call site for lockdep_rtnl_is_held()
outside COFIG_LOCK_PROVING an inline definition returning 1 is
needed. Similar to the rcu_read_lock_is_held().

Fixes: 2a47fa45d4df ("ixgbe: enable l2 forwarding acceleration for macvlans")
CC: Veaceslav Falico <vfalico@redhat.com>
Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Showing 2 changed files with 6 additions and 1 deletions Side-by-side Diff

include/linux/rtnetlink.h
Diff comments   View file @ 8532824
... ... @@ -24,6 +24,11 @@
24 24 extern int rtnl_is_locked(void);
25 25 #ifdef CONFIG_PROVE_LOCKING
26 26 extern int lockdep_rtnl_is_held(void);
  27 +#else
  28 +static inline int lockdep_rtnl_is_held(void)
  29 +{
  30 + return 1;
  31 +}
27 32 #endif /* #ifdef CONFIG_PROVE_LOCKING */
28 33  
29 34 /**
... ... @@ -4500,7 +4500,7 @@
4500 4500 {
4501 4501 struct netdev_adjacent *upper;
4502 4502  
4503   - WARN_ON_ONCE(!rcu_read_lock_held());
  4503 + WARN_ON_ONCE(!rcu_read_lock_held() && !lockdep_rtnl_is_held());
4504 4504  
4505 4505 upper = list_entry_rcu((*iter)->next, struct netdev_adjacent, list);
4506 4506