On Wed, Oct 12, 2016 at 09:20:29AM -0400, John Ferlan wrote: > > > On 10/12/2016 06:40 AM, Erik Skultety wrote: > > On Tue, Oct 11, 2016 at 05:25:49PM -0400, John Ferlan wrote: > >> https://bugzilla.redhat.com/show_bug.cgi?id=1357416 > >> > >> Rather than return a 0 or -1 and the *result string, return just the result > >> string to the caller. Alter all the callers to handle the different return. > >> > >> As a side effect or result of this, it's much clearer that we cannot just > >> assign the returned string into the scsi_host wwnn, wwpn, and fabric_wwn > >> fields - rather we should fetch a temporary string, then as long as our > >> fetch was good, VIR_FREE what may have been there, and STEAL what we just got. > >> This fixes a memory leak in the virNodeDeviceCreateXML code path through > >> find_new_device and nodeDeviceLookupSCSIHostByWWN which will continually > >> call nodeDeviceSysfsGetSCSIHostCaps until the expected wwnn/wwpn is found > >> in the device object capabilities. > >> > >> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx> > >> --- > >> > >> I suppose I could have made two patches out of this, but it felt like > >> overkill once I realized what the issue was. OK a third one line patch > >> could have been added to change the virGetFCHostNameByWWN comment as well, > >> but that'd really be overkill. > >> > >> src/node_device/node_device_linux_sysfs.c | 55 ++++++++++++------------------- > >> src/util/virutil.c | 34 ++++++++----------- > >> src/util/virutil.h | 9 +++-- > >> tests/fchosttest.c | 30 ++++++----------- > >> 4 files changed, 49 insertions(+), 79 deletions(-) > >> > >> diff --git a/src/node_device/node_device_linux_sysfs.c b/src/node_device/node_device_linux_sysfs.c > >> index 549d32c..be99c41 100644 > >> --- a/src/node_device/node_device_linux_sysfs.c > >> +++ b/src/node_device/node_device_linux_sysfs.c > >> @@ -44,8 +44,7 @@ VIR_LOG_INIT("node_device.node_device_linux_sysfs"); > >> int > >> nodeDeviceSysfsGetSCSIHostCaps(virNodeDevCapDataPtr d) > >> { > >> - char *max_vports = NULL; > >> - char *vports = NULL; > >> + char *tmp = NULL; > >> int ret = -1; > >> > >> if (virReadSCSIUniqueId(NULL, d->scsi_host.host, > >> @@ -59,64 +58,53 @@ nodeDeviceSysfsGetSCSIHostCaps(virNodeDevCapDataPtr d) > >> if (virIsCapableFCHost(NULL, d->scsi_host.host)) { > >> d->scsi_host.flags |= VIR_NODE_DEV_CAP_FLAG_HBA_FC_HOST; > >> > >> - if (virReadFCHost(NULL, > >> - d->scsi_host.host, > >> - "port_name", > >> - &d->scsi_host.wwpn) < 0) { > >> + if (!(tmp = virReadFCHost(NULL, d->scsi_host.host, "port_name"))) { > >> VIR_WARN("Failed to read WWPN for host%d", d->scsi_host.host); > >> goto cleanup; > >> } > >> + VIR_FREE(d->scsi_host.wwpn); > >> + VIR_STEAL_PTR(d->scsi_host.wwpn, tmp); > >> > >> - if (virReadFCHost(NULL, > >> - d->scsi_host.host, > >> - "node_name", > >> - &d->scsi_host.wwnn) < 0) { > >> + if (!(tmp = virReadFCHost(NULL, d->scsi_host.host, "node_name"))) { > >> VIR_WARN("Failed to read WWNN for host%d", d->scsi_host.host); > >> goto cleanup; > >> } > >> + VIR_FREE(d->scsi_host.wwnn); > >> + VIR_STEAL_PTR(d->scsi_host.wwnn, tmp); > >> > >> - if (virReadFCHost(NULL, > >> - d->scsi_host.host, > >> - "fabric_name", > >> - &d->scsi_host.fabric_wwn) < 0) { > >> + if (!(tmp = virReadFCHost(NULL, d->scsi_host.host, "fabric_name"))) { > >> VIR_WARN("Failed to read fabric WWN for host%d", > >> d->scsi_host.host); > >> goto cleanup; > >> } > >> + VIR_FREE(d->scsi_host.fabric_wwn); > >> + VIR_STEAL_PTR(d->scsi_host.fabric_wwn, tmp); > >> } > >> > > > > So if I understand correctly, the problem is basically that we did not call > > VIR_FREE on the data that had previously been filled to the virNodeDevCapData > > structure during replacing it with new data. So, we could just keep the > > signature of virReadFCHost as is and just add the VIR_FREE and VIR_STEAL_PTR > > to the function, thus there won't be any need to use VIR_FREE+STEAL repeatedly > > in here. > > > > True - we're overwriting the &d->scsi_host.{wwnn|wwpn|fabric_wwn} fields > and that's the primary issue (e.g. mem leak). > > While I understand your point, I'm not sure adding a VIR_FREE(*result) > to virReadFCHost just prior to the "if VIR_STRDUP(*result, p) < 0)" is a > proper solution since virReadFCHost does not "own" that memory. It > doesn't state that if *result has something in it, the code will perform > a VIR_FREE (although that's a nice convenience in this case). Sure it's > simple enough to add that comment, but then I believe that the I don't see a major problem here... > VIR_FREE() would have to be done at the top of the function; otherwise, > how does the caller distinguish which error occurred when -1 gets > returned and whether it should VIR_FREE itself? > Well, I have to admin that this^^ is a fair argument because there are 3 different spots where the function can fail, not that the caller could not check result for NULL but the fact that a function touched caller's argument and then failed would be just weird. So, yeah, good point. > Also, what if the caller didn't want the *result wiped out? What if it > was using it to compare what it found "this" time vs. what was present > in the data/file a previous time? That caller would then need to be > adjusted to pass a temporary variable anyway. Exactly, if a caller wanted to just compare 2 values - old and new one - they would use a temporary variable, that would IMHO be expected correct behaviour. Anyway, it's irrelevant now that I agree with your point above. > > I think for me most compelling reason to alter virReadFCHost is that it > follows the mindset of not returning two values from a function when one > is perfectly reasonable. > > John > > BTW: The OCD would still kick in and want to change the comment below to > match the function name... Yeah, since the patch is going to be relatively beefy, this change will blend in fairly easily, so go ahead, ACK. Erik NOTE: I've recently switched to mutt and it's still quite new, so I forgot to hit 'g' for group reply, therefore most of this conversation 'officially' never happened, so CC'ng libvir-list at least for the last bit, I suppose the whole 'thread' is going to look odd, sigh.... > > >> -/* virGetHostNameByWWN: > >> +/* virGetFCHostNameByWWN: > > > > Normally, I'd say sure, you're absolutely right about not creating a separate > > patch for this kind of change, but once you make the adjustment I mentioned > > above none of the below changes will be necessary and thus this rename change > > would look sort of unrelated imho. > > > > ACK with the adjustment. > > > > Erik > > > >> * > >> * Iterate over the sysfs tree to get FC host name (e.g. host5) > >> * by the provided "wwnn,wwpn" pair. > >> @@ -2298,7 +2293,7 @@ virFindFCHostCapableVport(const char *sysfs_prefix) > >> if (!virIsCapableVport(prefix, host)) > >> continue; > >> > >> - if (virReadFCHost(prefix, host, "port_state", &state) < 0) { > >> + if (!(state = virReadFCHost(prefix, host, "port_state"))) { > >> VIR_DEBUG("Failed to read port_state for host%d", host); > >> continue; > >> } > >> @@ -2310,12 +2305,12 @@ virFindFCHostCapableVport(const char *sysfs_prefix) > >> } > >> VIR_FREE(state); > >> > >> - if (virReadFCHost(prefix, host, "max_npiv_vports", &max_vports) < 0) { > >> + if (!(max_vports = virReadFCHost(prefix, host, "max_npiv_vports"))) { > >> VIR_DEBUG("Failed to read max_npiv_vports for host%d", host); > >> continue; > >> } > >> > >> - if (virReadFCHost(prefix, host, "npiv_vports_inuse", &vports) < 0) { > >> + if (!(vports = virReadFCHost(prefix, host, "npiv_vports_inuse"))) { > >> VIR_DEBUG("Failed to read npiv_vports_inuse for host%d", host); > >> VIR_FREE(max_vports); > >> continue; > >> @@ -2379,14 +2374,13 @@ virGetSCSIHostNameByParentaddr(unsigned int domain ATTRIBUTE_UNUSED, > >> return NULL; > >> } > >> > >> -int > >> +char * > >> virReadFCHost(const char *sysfs_prefix ATTRIBUTE_UNUSED, > >> int host ATTRIBUTE_UNUSED, > >> - const char *entry ATTRIBUTE_UNUSED, > >> - char **result ATTRIBUTE_UNUSED) > >> + const char *entry ATTRIBUTE_UNUSED) > >> { > >> virReportSystemError(ENOSYS, "%s", _("Not supported on this platform")); > >> - return -1; > >> + return NULL; > >> } > >> > >> bool > >> diff --git a/src/util/virutil.h b/src/util/virutil.h > >> index 703ec53..8c0d83c 100644 > >> --- a/src/util/virutil.h > >> +++ b/src/util/virutil.h > >> @@ -182,11 +182,10 @@ virGetSCSIHostNameByParentaddr(unsigned int domain, > >> unsigned int slot, > >> unsigned int function, > >> unsigned int unique_id); > >> -int virReadFCHost(const char *sysfs_prefix, > >> - int host, > >> - const char *entry, > >> - char **result) > >> - ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4); > >> +char *virReadFCHost(const char *sysfs_prefix, > >> + int host, > >> + const char *entry) > >> + ATTRIBUTE_NONNULL(3); > >> > >> bool virIsCapableFCHost(const char *sysfs_prefix, int host); > >> bool virIsCapableVport(const char *sysfs_prefix, int host); > >> diff --git a/tests/fchosttest.c b/tests/fchosttest.c > >> index e9b89a7..a08a2e8 100644 > >> --- a/tests/fchosttest.c > >> +++ b/tests/fchosttest.c > >> @@ -68,35 +68,25 @@ test3(const void *data ATTRIBUTE_UNUSED) > >> char *vports = NULL; > >> int ret = -1; > >> > >> - if (virReadFCHost(TEST_FC_HOST_PREFIX, > >> - TEST_FC_HOST_NUM, > >> - "node_name", > >> - &wwnn) < 0) > >> + if (!(wwnn = virReadFCHost(TEST_FC_HOST_PREFIX, TEST_FC_HOST_NUM, > >> + "node_name"))) > >> return -1; > >> > >> - if (virReadFCHost(TEST_FC_HOST_PREFIX, > >> - TEST_FC_HOST_NUM, > >> - "port_name", > >> - &wwpn) < 0) > >> + if (!(wwpn = virReadFCHost(TEST_FC_HOST_PREFIX, TEST_FC_HOST_NUM, > >> + "port_name"))) > >> goto cleanup; > >> > >> - if (virReadFCHost(TEST_FC_HOST_PREFIX, > >> - TEST_FC_HOST_NUM, > >> - "fabric_name", > >> - &fabric_wwn) < 0) > >> + if (!(fabric_wwn = virReadFCHost(TEST_FC_HOST_PREFIX, TEST_FC_HOST_NUM, > >> + "fabric_name"))) > >> goto cleanup; > >> > >> - if (virReadFCHost(TEST_FC_HOST_PREFIX, > >> - TEST_FC_HOST_NUM, > >> - "max_npiv_vports", > >> - &max_vports) < 0) > >> + if (!(max_vports = virReadFCHost(TEST_FC_HOST_PREFIX, TEST_FC_HOST_NUM, > >> + "max_npiv_vports"))) > >> goto cleanup; > >> > >> > >> - if (virReadFCHost(TEST_FC_HOST_PREFIX, > >> - TEST_FC_HOST_NUM, > >> - "npiv_vports_inuse", > >> - &vports) < 0) > >> + if (!(vports = virReadFCHost(TEST_FC_HOST_PREFIX, TEST_FC_HOST_NUM, > >> + "npiv_vports_inuse"))) > >> goto cleanup; > >> > >> if (STRNEQ(expect_wwnn, wwnn) || > >> -- > >> 2.7.4 > >> > >> -- > >> libvir-list mailing list > >> libvir-list@xxxxxxxxxx > >> https://www.redhat.com/mailman/listinfo/libvir-list
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