The rtnl_mutex was held to protect calls to dev_uc_add
and dev_uc_del. Holding rtnl is not required as those
functions make use of the netif_addr_lock* API to
protect the MAC changing.
This change fixes the following regression by removing
the rtnl usage when fcoe_update_src_mac is called.
https://bugzilla.kernel.org/show_bug.cgi?id=42918
the existing dependency chain (in reverse order) is:
-> #1 (&fip->ctlr_mutex){+.+...}:
[<c1091f70>] lock_acquire+0x80/0x1b0
[<c147655d>] mutex_lock_nested+0x6d/0x340
[<f8970c32>] fcoe_ctlr_link_up+0x22/0x180 [libfcoe]
[<f894620e>] fcoe_create+0x47e/0x6e0 [fcoe]
[<f8973dd3>] fcoe_transport_create+0x143/0x250 [libfcoe]
[<c10527e0>] param_attr_store+0x30/0x60
[<c1052696>] module_attr_store+0x26/0x40
[<c11a201e>] sysfs_write_file+0xae/0x100
[<c11449df>] vfs_write+0x8f/0x160
[<c1144cbd>] sys_write+0x3d/0x70
[<c147a0c4>] syscall_call+0x7/0xb
-> #0 (rtnl_mutex){+.+.+.}:
[<c109164b>] __lock_acquire+0x140b/0x1720
[<c1091f70>] lock_acquire+0x80/0x1b0
[<c147655d>] mutex_lock_nested+0x6d/0x340
[<c13a10c4>] rtnl_lock+0x14/0x20
[<f89445ac>] fcoe_update_src_mac+0x2c/0xb0 [fcoe]
[<f8971712>] fcoe_ctlr_timer_work+0x712/0xb60 [libfcoe]
[<c104fb69>] process_one_work+0x179/0x5d0
[<c10502f1>] worker_thread+0x121/0x2d0
[<c10550ed>] kthread+0x7d/0x90
[<c1481a82>] kernel_thread_helper+0x6/0x10
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&fip->ctlr_mutex);
lock(rtnl_mutex);
lock(&fip->ctlr_mutex);
lock(rtnl_mutex);
*** DEADLOCK ***
Signed-off-by: Robert Love <robert.w.love@intel.com>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
949e71f17d