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author | Robert Love <robert.w.love@intel.com> | 2012-03-13 18:22:12 -0700 |
---|---|---|
committer | James Bottomley <JBottomley@Parallels.com> | 2012-03-28 10:06:34 +0100 |
commit | 2280512342ead9a2858b1490b21e5bcaf4f4cfc7 (patch) | |
tree | 291775956c45bff076dfc172daded04510a37164 /drivers | |
parent | a165de82b08ddba1fc8b0c4eb56b9020f981c002 (diff) | |
download | linux-stable-2280512342ead9a2858b1490b21e5bcaf4f4cfc7.tar.gz linux-stable-2280512342ead9a2858b1490b21e5bcaf4f4cfc7.tar.bz2 linux-stable-2280512342ead9a2858b1490b21e5bcaf4f4cfc7.zip |
[SCSI] fcoe: Drop the rtnl_mutex before calling fcoe_ctlr_link_up
The rtnl_lock is primarily used to serialize networking
driver changes as well as to ensure that a networking driver
is not removed when making changes to it. fcoe also uses
the rtnl_lock to protect the fcoe hostlist.
fcoe_create holds the rtnl_lock over the entirity of the
routine including a the call to fcoe_ctlr_link_up.
This causes the below deadlock because fcoe_ctlr_link_up
acquires the fcoe_ctlr ctlr_mutex and this deadlocks with
a libfcoe thread that acquires the fcoe_ctlr ctlr_mutex and
then the rtnl_lock (to update a MAC address).
This patch drops the rtnl_lock before calling
fcoe_ctlr_link_up and therefore the deadlock is prevented.
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>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/scsi/fcoe/fcoe.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c index 58c88b0e8792..acb3767fdae4 100644 --- a/drivers/scsi/fcoe/fcoe.c +++ b/drivers/scsi/fcoe/fcoe.c @@ -2186,8 +2186,12 @@ static int fcoe_create(struct net_device *netdev, enum fip_state fip_mode) /* start FIP Discovery and FLOGI */ lport->boot_time = jiffies; fc_fabric_login(lport); - if (!fcoe_link_ok(lport)) + if (!fcoe_link_ok(lport)) { + rtnl_unlock(); fcoe_ctlr_link_up(&fcoe->ctlr); + mutex_unlock(&fcoe_config_mutex); + return rc; + } out_nodev: rtnl_unlock(); |