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author | Paul Gortmaker <paul.gortmaker@windriver.com> | 2014-01-14 16:03:37 -0500 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-13 10:41:47 -0800 |
commit | f76a1cbed18c86e2d192455f0daebb48458965f3 (patch) | |
tree | 6372a788551489c9fc68dfb82627c1970bdde4b1 /drivers/tty/serial | |
parent | 9be16b38cf43181efc12ee6f467aaf222ad31b03 (diff) | |
download | op-kernel-dev-f76a1cbed18c86e2d192455f0daebb48458965f3.zip op-kernel-dev-f76a1cbed18c86e2d192455f0daebb48458965f3.tar.gz |
hvc: ensure hvc_init is only ever called once in hvc_console.c
Commit 3e6c6f630a5282df8f3393a59f10eb9c56536d23 ("Delay creation of
khcvd thread") moved the call of hvc_init from being a device_initcall
into hvc_alloc, and used a non-null hvc_driver as indication of whether
hvc_init had already been called.
The problem with this is that hvc_driver is only assigned a value
at the bottom of hvc_init, and so there is a window where multiple
hvc_alloc calls can be in progress at the same time and hence try
and call hvc_init multiple times. Previously the use of device_init
guaranteed that hvc_init was only called once.
This manifests itself as sporadic instances of two hvc_init calls
racing each other, and with the loser of the race getting -EBUSY
from tty_register_driver() and hence that virtual console fails:
Couldn't register hvc console driver
virtio-ports vport0p1: error -16 allocating hvc for port
Here we add an atomic_t to guarantee we'll never run hvc_init twice.
Cc: stable@vger.kernel.org # v2.6.24+
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes: 3e6c6f630a52 ("Delay creation of khcvd thread")
Reported-by: Jim Somerville <Jim.Somerville@windriver.com>
Tested-by: Jim Somerville <Jim.Somerville@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial')
0 files changed, 0 insertions, 0 deletions