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author | Juergen Gross <jgross@suse.com> | 2017-05-18 18:28:47 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-06-29 14:00:27 +0300 |
commit | e5c49c1703ae906a8f41f58aabd5258a06fc9e6d (patch) | |
tree | e7bc575f341c1aa1957aa794edaa75f9c3f1dd6e /drivers/dma | |
parent | 0e051f17bd048d96eb533f1b8f436f3b27c6109b (diff) | |
download | linux-e5c49c1703ae906a8f41f58aabd5258a06fc9e6d.tar.xz |
xen/blkback: fix disconnect while I/Os in flight
commit 46464411307746e6297a034a9983a22c9dfc5a0c upstream.
Today disconnecting xen-blkback is broken in case there are still
I/Os in flight: xen_blkif_disconnect() will bail out early without
releasing all resources in the hope it will be called again when
the last request has terminated. This, however, won't happen as
xen_blkif_free() won't be called on termination of the last running
request: xen_blkif_put() won't decrement the blkif refcnt to 0 as
xen_blkif_disconnect() didn't finish before thus some xen_blkif_put()
calls in xen_blkif_disconnect() didn't happen.
To solve this deadlock xen_blkif_disconnect() and
xen_blkif_alloc_rings() shouldn't use xen_blkif_put() and
xen_blkif_get() but use some other way to do their accounting of
resources.
This at once fixes another error in xen_blkif_disconnect(): when it
returned early with -EBUSY for another ring than 0 it would call
xen_blkif_put() again for already handled rings on a subsequent call.
This will lead to inconsistencies in the refcnt handling.
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Steven Haigh <netwiz@crc.id.au>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/dma')
0 files changed, 0 insertions, 0 deletions