Re: [libvirt] [PATCHv3 4/5] network: change cleanup: to success/cleanup/error: in network*() functions
On 08/14/2012 04:17 PM, Laine Stump wrote:
A later patch will be adding a counter that will be
incremented/decremented each time an guest interface starts/stops
using a particular network. For this to work, all types of networks
need to go through a common return sequence rather than returning
early. To setup for this, the existing a new success: label is added
s/the existing//
(when necessary), a new error: label is added which does any cleanup
necessary only for error returns and then does goto cleanup, and early
returns are changed to goto error if it's a failure, or goto success
if it's successful. This way the intent of all the gotos is
unambiguous, and a successful return path never encounters the
"error:" label.
---
Change from v1: at Eric's suggestion, instead of having a cleanup label jumped to on
success, and an inline "error" label jumped to on failure:
I modified these function so that they have three labels:
success:
/* anything only done on success */
ret = 0;
cleanup:
/* common cleanup */
return ret;
error:
/* anything only done on error */
goto cleanup;
Yep, that style is fine with me. An alternative style (but no need to
respin now) would be:
success:
/* anything done only on success */
ret = 0;
cleanup:
if (ret < 0) {
/* anything only done on error */
}
return ret;
but while it is fewer labels and no backwards goto, it loses out on the
nice 'goto error' naming, so you are just trading one style for another
with no real benefit.
This has the dual advantage of making the intent of all gotos
painfully clear, as well as not confusing anyone by having the control
flow of a successful exit go past the error: label.
src/network/bridge_driver.c | 124 ++++++++++++++++++++++++--------------------
1 file changed, 69 insertions(+), 55 deletions(-)
ACK as-is.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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