[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2] libxenstore: prefer using the character device
On Thu, Aug 27, 2015 at 09:04:38AM -0500, Jonathan Creekmore wrote: > With the addition of FMODE_ATOMIC_POS in the Linux 3.14 kernel, > concurrent blocking file accesses to a single open file descriptor can > cause a deadlock trying to grab the file position lock. If a watch has > been set up, causing a read_thread to blocking read on the file > descriptor, then future writes that would cause the background read to > complete will block waiting on the file position lock before they can > execute. This race condition only occurs when libxenstore is accessing > the xenstore daemon through the /proc/xen/xenbus file and not through > the unix domain socket, which is the case when the xenstore daemon is > running as a stub domain or when oxenstored is passed > --disable-socket. Accessing the daemon from the true character device > also does not exhibit this problem. > > On Linux, prefer using the character device file over the proc file if > the character device exists. > > Signed-off-by: Jonathan Creekmore <jonathan.creekmore@xxxxxxxxx> Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx> I think this is a candidate for 4.6. > --- > tools/xenstore/xs_lib.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/tools/xenstore/xs_lib.c b/tools/xenstore/xs_lib.c > index af4f75a..0c7744e 100644 > --- a/tools/xenstore/xs_lib.c > +++ b/tools/xenstore/xs_lib.c > @@ -81,6 +81,8 @@ const char *xs_domain_dev(void) > #if defined(__RUMPUSER_XEN__) || defined(__RUMPRUN__) > return "/dev/xen/xenbus"; > #elif defined(__linux__) > + if (access("/dev/xen/xenbus", F_OK) == 0) > + return "/dev/xen/xenbus"; > return "/proc/xen/xenbus"; > #elif defined(__NetBSD__) > return "/kern/xen/xenbus"; > -- > 2.1.4 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |