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author | Farhan Ali <alifm@linux.ibm.com> | 2019-04-17 00:23:14 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-31 16:47:35 +0300 |
commit | 3d5e860adfb3901fde8300c91734d7480fc72d7a (patch) | |
tree | d001cd2b8658ecc9a4b99fb22676daef1d73826d /fs | |
parent | ce16889c87c2e9b5eb4d79a7072190e4ca7364d0 (diff) | |
download | linux-3d5e860adfb3901fde8300c91734d7480fc72d7a.tar.xz |
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 'fs')
0 files changed, 0 insertions, 0 deletions