brcmsmac: fix deadlock on missing firmware
When brcm80211 firmware is not installed networking hangs.
A deadlock happens because we call ieee80211_unregister_hw()
from the .start callback of struct ieee80211_ops. When .start
is called we are under rtnl lock and ieee80211_unregister_hw()
tries to take it again.
Function call stack:
dev_change_flags()
__dev_change_flags()
__dev_open()
ASSERT_RTNL() <-- Assert rtnl lock
ops->ndo_open()
.ndo_open = ieee80211_open,
ieee80211_open()
ieee80211_do_open()
drv_start()
local->ops->start()
.start = brcms_ops_start,
brcms_ops_start()
brcms_remove()
ieee80211_unregister_hw()
rtnl_lock() <-- Here we deadlock
Introduced by:
commit 25b5632fb35ca61b8ae3eee235edcdc2883f7a5e
("brcmsmac: request firmware in .start() callback")
This patch fixes the bug by removing the call to brcms_remove()
and moves the brcms_request_fw() call to the top of the .start
callback to not initiate anything unless firmware is installed.
Signed-off-by: Emil Goode <emilgoode@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1 file changed