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There are variants of qemu_create_pidfile() in qemu-pr-helper and
qemu-ga. Let's have a common implementation in libqemuutil.
The code is initially based from pr-helper write_pidfile(), with
various improvements and suggestions from Daniel Berrangé:
QEMU will leave the pidfile existing on disk when it exits which
initially made me think it avoids the deletion race. The app
managing QEMU, however, may well delete the pidfile after it has
seen QEMU exit, and even if the app locks the pidfile before
deleting it, there is still a race.
eg consider the following sequence
QEMU 1 libvirtd QEMU 2
1. lock(pidfile)
2. exit()
3. open(pidfile)
4. lock(pidfile)
5. open(pidfile)
6. unlink(pidfile)
7. close(pidfile)
8. lock(pidfile)
IOW, at step 8 the new QEMU has successfully acquired the lock, but
the pidfile no longer exists on disk because it was deleted after
the original QEMU exited.
While we could just say no external app should ever delete the
pidfile, I don't think that is satisfactory as people don't read
docs, and admins don't like stale pidfiles being left around on
disk.
To make this robust, I think we might want to copy libvirt's
approach to pidfile acquisition which runs in a loop and checks that
the file on disk /after/ acquiring the lock matches the file that
was locked. Then we could in fact safely let QEMU delete its own
pidfiles on clean exit..
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180831145314.14736-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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After commit b3f1c8c413bc83e4a2cc7a63e4eddf9fe6449052 "qemu-pr-helper: use new
libmultipath API", QEMU started using new libmultipath API, which is not
available on CentOS 7.x.
This fixes that by probing the new libmultipath API in configure. If it fails,
then try probing the old API. If it fails, then consider libmultipath not
available.
With this, configure script defines CONFIG_MPATH_NEW_API that is used in
scsi/qemu-pr-helper.c to use the new libmultipath API.
Fixes: b3f1c8c413bc83e4a2cc7a63e4eddf9fe6449052
BugLink: https://bugs.launchpad.net/qemu/+bug/1786343
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Message-Id: <20180810141116.24016-1-muriloo@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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When reviewing Paolo's pr-helper patches I've noticed couple of
problems:
1) socket_path needs to be calculated at two different places
(one for printing out help, the other if socket activation is NOT
used),
2) even though the default socket_path is allocated in
compute_default_paths() it is the only default path the function
handles. For instance, pidfile is allocated outside of this
function. And yet again, at different places than 1)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <c791ba035f26ea957e8f3602e3009b621769b1ba.1530611283.git.mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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After reading a PR IN command with zero request size in prh_read_request,
the resp->result field will be uninitialized and the resp.sz field will
be also uninitialized when returning to prh_co_entry.
If resp->result == GOOD (from a previous successful reply or just luck),
then the assert in prh_write_response might not be triggered and
uninitialized response will be sent.
The fix is to remove the whole handling of sz == 0 in prh_co_entry.
Those errors apply only to PR OUT commands and it's perfectly okay to
catch them later in do_pr_out and multipath_pr_out; the check for
too-short parameters in fact doesn't apply in the easy SG_IO case, as
it can be left to the target firmware even.
The result is that prh_read_request does not fail requests anymore and
prh_co_entry becomes simpler.
Reported-by: Dima Stepanov <dimastep@yandex-team.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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The response size is expected to be zero if the SCSI status is not
"GOOD", but nothing was resetting it.
This can be reproduced simply by "sg_persist -s /dev/sdb" where /dev/sdb
in the guest is a scsi-block device corresponding to a multipath device
on the host.
Before:
PR in (Read full status): Aborted command
and on the host:
prh_write_response: Assertion `resp->sz == 0' failed.
After:
PR in (Read full status): bad field in cdb or parameter list
(perhaps unsupported service action)
Reported-by: Jiri Belka <jbelka@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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Currently --help shows "(default '(null)')" for the -k/--socket-path
option. Fix it by getting the default path in /var/run.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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Let's write pidfile even if user did not request --daemon but
they requested just --pidfile. Libvirt will use exactly this.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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After we've dropped privileges it might be not possible to write
pidfile. For instance, if this binary is run as root (because
user wants it to write pidfile to some privileged location)
writing pidfile fails because privileges are dropped before we
even get to that.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Due to wrong specification of arguments to getopt_long() any
attempt to set pidfile resulted in:
1) the default to be leaked
2) the @pidfile variable to be set to NULL (because optarg is
NULL without this patch).
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <6f10cd53d361a395aa0e85a9311ec4e9a8fc11e5.1521868451.git.mprivozn@redhat.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Since commit 67a1de0d195a there is no space anymore between the
version number and the parentheses when running configure with
--with-pkgversion=foo :
$ qemu-system-s390x --version
QEMU emulator version 2.11.50(foo)
But the space is included when building without that option
when building from a git checkout:
$ qemu-system-s390x --version
QEMU emulator version 2.11.50 (v2.11.0-1494-gbec9c64-dirty)
The same confusion exists with the "query-version" QMP command.
Let's fix this by introducing a proper QEMU_FULL_VERSION definition
that includes the space and parentheses, while the QEMU_PKGVERSION
should just cleanly contain the package version string itself.
Note that this also changes the behavior of the "query-version" QMP
command (the space and parentheses are not included there anymore),
but that's supposed to be OK since the strings there are not meant
to be parsed by other tools.
Fixes: 67a1de0d195a6185c39b436159c9ffc7720bf979
Buglink: https://bugs.launchpad.net/qemu/+bug/1673373
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1518692807-25859-1-git-send-email-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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1) Return a generic sense if TEST UNIT READY does not provide one;
2) Fix two mistakes in copying from the spec.
Cc: qemu-stable@nongnu.org
Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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libmultipath has recently changed its API. The new API supports multi-threaded
clients better. Unfortunately there is no backwards-compatibility, so we just
switch to the new one. Running QEMU compiled with the new library on the old
library will likely crash, while doing the opposite will cause QEMU not to
start at all (because udev, get_multipath_config and put_multipath_config
are undefined).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Proper support of persistent reservation for multipath devices requires
communication with the multipath daemon, so that the reservation is
registered and applied when a path comes up. The device mapper
utilities provide a library to do so; this patch makes qemu-pr-helper.c
detect multipath devices and, when one is found, delegate the operation
to libmpathpersist.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Introduce a privileged helper to run persistent reservation commands.
This lets virtual machines send persistent reservations without using
CAP_SYS_RAWIO or out-of-tree patches. The helper uses Unix permissions
and SCM_RIGHTS to restrict access to processes that can access its socket
and prove that they have an open file descriptor for a raw SCSI device.
The next patch will also correct the usage of persistent reservations
with multipath devices.
It would also be possible to support for Linux's IOC_PR_* ioctls in
the future, to support NVMe devices. For now, however, only SCSI is
supported.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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