Re: [RFC v5 054/126] virtio-9p: introduce ERRP_AUTO_PROPAGATE

[Greg Kurz]

On Tue, 19 Nov 2019 16:59:23 +0000
Vladimir Sementsov-Ogievskiy <address@hidden> wrote:

> 19.11.2019 19:56, Greg Kurz wrote:
> > Sorry for the late review...
> > 
> > On Fri, 11 Oct 2019 19:04:40 +0300
> > Vladimir Sementsov-Ogievskiy <address@hidden> wrote:
> > 
> >> If we want to add some info to errp (by error_prepend() or
> >> error_append_hint()), we must use the ERRP_AUTO_PROPAGATE macro.
> >> Otherwise, this info will not be added when errp == &fatal_err
> > 
> > s/fatal_err/error_fatal/
> > 
> >> (the program will exit prior to the error_append_hint() or
> >> error_prepend() call).  Fix such cases.
> >>
> >> If we want to check error after errp-function call, we need to
> >> introduce local_err and than propagate it to errp. Instead, use
> > 
> > s/than/then
> > 
> >> ERRP_AUTO_PROPAGATE macro, benefits are:
> >> 1. No need of explicit error_propagate call
> >> 2. No need of explicit local_err variable: use errp directly
> >> 3. ERRP_AUTO_PROPAGATE leaves errp as is if it's not NULL or
> >>     &error_fatel, this means that we don't break error_abort
> > 
> > s/error_fatel/error_fatal
> > 
> >>     (we'll abort on error_set, not on error_propagate)
> >>
> >> This commit (together with its neighbors) was generated by
> >>
> >> for f in $(git grep -l errp \*.[ch]); do \
> >>      spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
> >>      --macro-file scripts/cocci-macro-file.h --in-place --no-show-diff $f; 
> >> \
> >> done;
> >>
> >> then fix a bit of compilation problems: coccinelle for some reason
> >> leaves several
> >> f() {
> >>      ...
> >>      goto out;
> >>      ...
> >>      out:
> >> }
> >> patterns, with "out:" at function end.
> >>
> >> then
> >> ./python/commit-per-subsystem.py MAINTAINERS "$(< auto-msg)"
> >>
> >> (auto-msg was a file with this commit message)
> >>
> >> Still, for backporting it may be more comfortable to use only the first
> >> command and then do one huge commit.
> >>
> >> Reported-by: Kevin Wolf <address@hidden>
> >> Reported-by: Greg Kurz <address@hidden>
> >> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> >> ---
> >>   hw/9pfs/9p-local.c | 8 ++++----
> >>   hw/9pfs/9p.c       | 1 +
> >>   2 files changed, 5 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> >> index 35635e7e7e..aac7989f16 100644
> >> --- a/hw/9pfs/9p-local.c
> >> +++ b/hw/9pfs/9p-local.c
> >> @@ -1477,9 +1477,9 @@ static void error_append_security_model_hint(Error 
> >> **errp_in)
> >>   
> >>   static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error 
> >> **errp)
> >>   {
> >> +    ERRP_AUTO_PROPAGATE();
> >>       const char *sec_model = qemu_opt_get(opts, "security_model");
> >>       const char *path = qemu_opt_get(opts, "path");
> >> -    Error *local_err = NULL;
> >>   
> >>       if (!sec_model) {
> >>           error_setg(errp, "security_model property not set");
> >> @@ -1507,9 +1507,9 @@ static int local_parse_opts(QemuOpts *opts, 
> >> FsDriverEntry *fse, Error **errp)
> >>           return -1;
> >>       }
> >>   
> >> -    fsdev_throttle_parse_opts(opts, &fse->fst, &local_err);
> >> -    if (local_err) {
> >> -        error_propagate_prepend(errp, local_err,
> >> +    fsdev_throttle_parse_opts(opts, &fse->fst, errp);
> >> +    if (*errp) {
> >> +        error_prepend(errp,
> >>                                   "invalid throttle configuration: ");
> > 
> > The change looks good, apart from the funky indentation.
> > 
> >>           return -1;
> >>       }
> >> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> >> index cce2366219..1df2749e03 100644
> >> --- a/hw/9pfs/9p.c
> >> +++ b/hw/9pfs/9p.c
> >> @@ -3552,6 +3552,7 @@ void pdu_submit(V9fsPDU *pdu, P9MsgHeader *hdr)
> >>   int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t,
> >>                                  Error **errp)
> >>   {
> >> +    ERRP_AUTO_PROPAGATE();
> > 
> > I don't know coccinelle so I'm not sure why ERRP_AUTO_PROPAGATE() was
> > added here... but it's definitely not needed in this function.
> 
> 
> Because this function calls error_prepend()
> 

My bad, sorry for the noise and:

Acked-by: Greg Kurz <address@hidden>

> > 
> >>       int i, len;
> >>       struct stat stat;
> >>       FsDriverEntry *fse;
> > 
> 
>