diff options
| author | Farhan Ali <alifm@linux.ibm.com> | 2019-04-16 17:23:14 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-31 06:46:35 -0700 |
| commit | 6956c0e3cf330cb6176c02e0ebdb4a3066b94ee1 (patch) | |
| tree | 59d9c8dde3be9c8499aa7b0a07dde04a6e59ce19 /drivers/gpu/drm | |
| parent | 476e87eb7f78b344c2312c74cc289b1843deadd8 (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')
0 files changed, 0 insertions, 0 deletions