Clang points out:
tap-ctl-list.c:457:28: error: variable 'entry' is uninitialized when
used here [-Werror,-Wuninitialized]
for (; *_entry != NULL; ++entry) {
^~~~~
The content of that loop clearly was meant to iterate over _entry rather than
entry, so is fixed to do so. This presumably fixes a memory leak when
tapdisks get orphed, as only the first item on the list got freed.
There is no use of entry at all. It is referenced in a
list_for_each_entry(tl, &tap->list, entry) construct, but this is just a
member name, and not a reference to local scope variable of the same name.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Doug Goldstein <cardoe@cardoe.com>
The original rule to target "distclean" in tools/Rules.mk was in effect
"make clean". It should be "make distclean".
However not all Makefiles in subdirectories have distclean target
defined. So this patch also adds a bunch of distclean targets to various
Makefiles. They only depend on clean target and don't have any actions
in most cases.
With the patch applied, following command outputs 0 results:
find tools -name 'Makefile*' -exec grep -L 'distclean' {} \+ \
| grep -v ocaml | grep -v libfsimage
Ocaml and libfsimage are known to have distclean defined in a dedicated
rules file.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
The following patch:
tools: Retry blktap2 tapdisk message on interrupt.
Addressed a long standing regression with the blktap2 control
plane. An interruption of the select system call would
prematurely terminate the message sequence needed to properly
shutdown a blktap2 tapdisk instance.
Ian Jackson correctly noted that the read and write systems calls
responsible for receiving and sending the control messages could
also return EINTR resulting in similar effects. While this
regression was not noted in field testing this patch adds support
to re-start the calls to provide a technically complete
implementation of control plane management in the presence of
signals.
Signed-off-by: Dr. Greg Wettstein <xen@wind.enjellic.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Re-start blktap2 IPC select call on interrupt.
We hunted this miserable bug for a long time.
The teardown of a blktap2 tapdisk instance is being carried out
inconsistently up to and including the 4.2.1 release. The
problem appears to be a classic 'Heisenbug' which disappears if a
single function call is added to the tapdisk shutdown path. It
is likely this bug has been in existence for the life of the
blktap2 code.
Control messages to manipulate a tapdisk instance are sent over a
UNIX domain socket. A select call is used on both the read and
write paths to wait on I/O and to set a timeout for the
transmission and reception of the control plane messages.
The existing code fails receipt or transmission of the control message
on any type of error return from the select call. The xl control
process receives an interrupt while waiting in the select call which
in turn causes an error return with SIGINT as the return code.
This prematurely terminates the teardown of the tapdisk instance
leaving it in various states of shutdown. Since multiple messages
are needed to implement a full teardown the tapdisk instance can be
left in various states ranging from fully connected to only the minor
being left allocated.
The fix is straight forward. Check the return code from the
select call and re-try read or write of the control message if
errno is sent to EINTR. The problem manifests itself in the read
path but there appears to be little reason to not add the fix to
the write path as well. Both paths appear to be cut-and-paste
copies of each other.
Signed-off-by: Dr. Greg Wettstein <greg@enjellic.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Failure here means that a disk will not be correctly setup. I briefly
scanned tools/blktap2/control.c for other goto constructs which did not
set their err variable but didn't see any others.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
19025:bd78714b8594 switched to "-MMD -MF" in preference, adding the
correct runes to tools/Rules.mk but appears to have missed some other
uses of -Wp,...
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Otherwise make can search the path relative to certain standard paths
such as /usr/include (e.g., the line '-include $(XEN_ROOT)/.config' in
Config.mk suffers from this).
Signed-off-by: Keir Fraser <keir@xen.org>
Add an SONAME to libblktapctl.so.
Install static library as data to avoid executable permissions in the .a file.
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
tools/blktap2/control/Makefile | 35 +++++++++++++++++++++++++----------
1 file changed, 25 insertions(+), 10 deletions(-)
This has not caused crashes because generally use after free is OK
provided nothing else is going on. However the patch makes things
correct. It also allows us to use heap poisoning feature of valgrind on
tools linking to libblktapctl.
Signed-off-by: Gianni Tedesco <gianni.tedesco@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tapdisk control in userspace, a replacement for the original blktap2
control stack, which had to pass a kernel space interface based on
sysfs nodes.
All tapdisk processes listen for commands on a unix stream socket. The
control library supports scanning the socket namespace for running
tapdisks, VBD minors allocated, associated images and state inquiry.
Control operations include allocating/releasing devices, spawning
tapdisks, opening/closing images, attaching disk images to
devices. disk pause/resume operations and runtime switching of disk
images.
Signed-off-by: Jake Wires <jake.wires@citrix.com>
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Wei Liu
Andrew Cooper
Olaf Hering
Dr. Greg Wettstein
Ian Campbell
Keir Fraser
Gianni Tedesco
Keir Fraser