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Re: [libvirt] [PATCH v3] virsh: avoid missing zero value judgement in cmdBlkiotune



On 28.07.2011 12:38, Alex Jia wrote:
On 07/28/2011 05:50 PM, Wen Congyang wrote:
At 07/28/2011 05:52 PM, Alex Jia Write:
* tools/virsh.c: avoid missing zero value judgement in cmdBlkiotune,
when
weight is equal to 0, the cmdBlkiotune will not raise any error
information
when judge weight value first time, and execute else branch to judge
weight
value again, strncpy(temp->field, VIR_DOMAIN_BLKIO_WEIGHT,
sizeof(temp->field))
will be not executed for ever. However, if and only if param->field
is equal
to VIR_DOMAIN_BLKIO_WEIGHT, underlying qemuDomainSetBlkioParameters
function
will check whether weight value is in range [100, 1000].

* how to reproduce?

% virsh blkiotune ${guestname} --weight 0

Signed-off-by: Alex Jia<ajia redhat com>
---
tools/virsh.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/virsh.c b/tools/virsh.c
index 8bd22dc..f24050d 100644
--- a/tools/virsh.c
+++ b/tools/virsh.c
@@ -4037,12 +4037,12 @@ cmdBlkiotune(vshControl * ctl, const vshCmd *
cmd)
goto cleanup;
}

- if (weight) {
- nparams++;
- if (weight< 0) {
+ if (vshCommandOptInt(cmd, "weight",&weight)> 0) {
Why you call vshCommandOptInt(cmd, "weight",&weight) again?
Make sure weight indeed exists and then checking whether its value is
right.

if do it like this:

if (weight<= 0) {
vshError(ctl, _("Invalid value of %d for I/O weight"), weight);
goto cleanup;
}

nparams++;
......

when I run virsh blkiotune ${guestname} --weight 0, I will not hit this
error,
and when I get weight value by virsh blkiotune ${guestname}, this error
will be
hit, because vshCommandOptInt(cmd, "weight",&weight) will return 0 and
unchange
weight value, it means weight will keep initial 0 value, hence vshError
will be
raise.

Thanks,

Alex


Our point is, you can store the return value of vshCommandOptInt (a few lines above)
and then just check against it instead of running the function again.

Michal


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