On 03/04/2013 03:19 PM, Laszlo Ersek wrote: > Signed-off-by: Laszlo Ersek <ler...@redhat.com> > --- > qga/commands-posix.c | 51 > ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 51 insertions(+), 0 deletions(-) > > diff --git a/qga/commands-posix.c b/qga/commands-posix.c > index d4b6bdc..1848df8 100644 > --- a/qga/commands-posix.c > +++ b/qga/commands-posix.c > @@ -40,6 +40,7 @@ extern char **environ; > #include <arpa/inet.h> > #include <sys/socket.h> > #include <net/if.h> > +#include <inttypes.h> > > #ifdef FIFREEZE > #define CONFIG_FSFREEZE > @@ -1178,7 +1179,57 @@ GuestLogicalProcessorList *qmp_guest_get_vcpus(Error > **errp) > > void qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp) > { > +#if defined(__linux__) > + const GuestLogicalProcessorList *entry; > + Error *local_err = NULL; > + > + for (entry = vcpus; local_err == NULL && entry != NULL; > + entry = entry->next) { > + const GuestLogicalProcessor *vcpu; > + > + vcpu = entry->value; > + if (vcpu->logical_id == 0) { > + if (!vcpu->online) { > + error_setg(&local_err, > + "unable to offline logical processor #0"); > + }
This is not quite accurate; my understanding is that there are setups where cpu0 can be offlined. More accurate would be to reject attempts to offline ANY cpu where the cpu/cpuNN/online file does not exist (which will catch the fact that cpu0 must always be on for the hardware you are testing with). > + } else { > + char *buf; > + FILE *f; > + > + buf = g_strdup_printf("/sys/devices/system/cpu/cpu%"PRId64 > + "/online", vcpu->logical_id); > + f = fopen(buf, "r+"); > + if (f == NULL) { > + error_setg_errno(&local_err, errno, "fopen(\"%s\", \"r+\")", > + buf); Again, if the file doesn't exist, but the user asked for online, then this should not be an error. > + } else { > + unsigned online; > + > + if (fscanf(f, "%u", &online) != 1) { > + error_setg(&local_err, "failed to read or parse \"%s\"", > + buf); Does doing a scan of the file's existing contents buy us any safety? Why not just blindly write into the file, instead of first reading it? > + } else if ((online != 0) != vcpu->online) { > + errno = 0; > + rewind(f); > + if (errno != 0 || > + fprintf(f, "%u\n", (unsigned)vcpu->online) < 0) { Do you really want to be printing NUL or \1? I though the kernel interface expected the literal character '0' or '1' (in ascii, \x30 or \x31). Why even bother with stdio buffering? Wouldn't it be simpler to open()/write() instead of fopen()/fprintf()? > + error_setg_errno(&local_err, errno, > + "rewind()/fprintf() on \"%s\"", > buf); > + } > + } > + > + if (fclose(f) == EOF && local_err == NULL) { > + error_setg_errno(&local_err, errno, "fclose(\"%s\")", > buf); > + } > + } > + g_free(buf); > + } > + } > + error_propagate(errp, local_err); > +#else > error_set(errp, QERR_UNSUPPORTED); > +#endif > } > > /* register init/cleanup routines for stateful command groups */ > -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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