diff options
author | Farhan Ali <alifm@linux.ibm.com> | 2019-04-16 17:23:14 -0400 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-31 06:45:23 -0700 |
commit | 48c7d1ea6d21361cabd42dbed7e6474e3f4d519f (patch) | |
tree | 7802892d3661e8d816dac17cbfb22c049f93629c /drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | |
parent | eb42f17258282986e47af5796f8b6ea8093cdabb (diff) |
vfio-ccw: Prevent quiesce function going into an infinite loop
[ Upstream commit d1ffa760d22aa1d8190478e5ef555c59a771db27 ]
The quiesce function calls cio_cancel_halt_clear() and if we
get an -EBUSY we go into a loop where we:
- wait for any interrupts
- flush all I/O in the workqueue
- retry cio_cancel_halt_clear
During the period where we are waiting for interrupts or
flushing all I/O, the channel subsystem could have completed
a halt/clear action and turned off the corresponding activity
control bits in the subchannel status word. This means the next
time we call cio_cancel_halt_clear(), we will again start by
calling cancel subchannel and so we can be stuck between calling
cancel and halt forever.
Rather than calling cio_cancel_halt_clear() immediately after
waiting, let's try to disable the subchannel. If we succeed in
disabling the subchannel then we know nothing else can happen
with the device.
Suggested-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Message-Id: <4d5a4b98ab1b41ac6131b5c36de18b76c5d66898.1555449329.git.alifm@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c')
0 files changed, 0 insertions, 0 deletions