2007-11-14 02:05:47

by Joe Perches

[permalink] [raw]
Subject: [PATCH] - [7/15] - remove defconfig ptr comparisons to 0 - fs/lockd

Remove defconfig ptr comparison to 0

Remove sparse warning: Using plain integer as NULL pointer

Signed-off-by: Joe Perches <[email protected]>

---

diff --git a/fs/lockd/svcshare.c b/fs/lockd/svcshare.c
index 068886d..98548ad 100644
--- a/fs/lockd/svcshare.c
+++ b/fs/lockd/svcshare.c
@@ -71,7 +71,7 @@ nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
struct nlm_share *share, **shpp;
struct xdr_netobj *oh = &argp->lock.oh;

- for (shpp = &file->f_shares; (share = *shpp) != 0; shpp = &share->s_next) {
+ for (shpp = &file->f_shares; (share = *shpp); shpp = &share->s_next) {
if (share->s_host == host && nlm_cmp_owner(share, oh)) {
*shpp = share->s_next;
kfree(share);



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2007-11-14 02:40:52

by NeilBrown

[permalink] [raw]
Subject: Re: [PATCH] - [7/15] - remove defconfig ptr comparisons to 0 - fs/lockd

On Tuesday November 13, [email protected] wrote:
> Remove defconfig ptr comparison to 0
>
> Remove sparse warning: Using plain integer as NULL pointer
>
> Signed-off-by: Joe Perches <[email protected]>
>
> ---
>
> diff --git a/fs/lockd/svcshare.c b/fs/lockd/svcshare.c
> index 068886d..98548ad 100644
> --- a/fs/lockd/svcshare.c
> +++ b/fs/lockd/svcshare.c
> @@ -71,7 +71,7 @@ nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
> struct nlm_share *share, **shpp;
> struct xdr_netobj *oh = &argp->lock.oh;
>
> - for (shpp = &file->f_shares; (share = *shpp) != 0; shpp = &share->s_next) {
> + for (shpp = &file->f_shares; (share = *shpp); shpp = &share->s_next) {
> if (share->s_host == host && nlm_cmp_owner(share, oh)) {
> *shpp = share->s_next;
> kfree(share);
>

I particularly disagree with this change as it now looked like it
could be an '==' comparison that was mistyped. Making it
....; (share = *shpp) != NULL; ....

makes the intent clear.

NeilBrown

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2007-11-14 04:45:07

by Trond Myklebust

[permalink] [raw]
Subject: Re: [PATCH] - [7/15] - remove defconfig ptr comparisons to 0 - fs/lockd


On Wed, 2007-11-14 at 13:40 +1100, Neil Brown wrote:
> On Tuesday November 13, [email protected] wrote:
> > Remove defconfig ptr comparison to 0
> >
> > Remove sparse warning: Using plain integer as NULL pointer
> >
> > Signed-off-by: Joe Perches <[email protected]>
> >
> > ---
> >
> > diff --git a/fs/lockd/svcshare.c b/fs/lockd/svcshare.c
> > index 068886d..98548ad 100644
> > --- a/fs/lockd/svcshare.c
> > +++ b/fs/lockd/svcshare.c
> > @@ -71,7 +71,7 @@ nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
> > struct nlm_share *share, **shpp;
> > struct xdr_netobj *oh = &argp->lock.oh;
> >
> > - for (shpp = &file->f_shares; (share = *shpp) != 0; shpp = &share->s_next) {
> > + for (shpp = &file->f_shares; (share = *shpp); shpp = &share->s_next) {
> > if (share->s_host == host && nlm_cmp_owner(share, oh)) {
> > *shpp = share->s_next;
> > kfree(share);
> >
>
> I particularly disagree with this change as it now looked like it
> could be an '==' comparison that was mistyped. Making it
> ....; (share = *shpp) != NULL; ....

There would also be the minor fact that the original test is being
inverted in this 'fix'. An accurate fix should at the very least be
!(share = *shpp).

> makes the intent clear.

It would be a lot cleaner just to pull the entire assignment out of the
for() statement. IOW:

for (shpp = &file->f_shares; *shpp != NULL; shpp = &(*shpp)->s_next) {
struct nlm_share *share = *shpp;

2007-11-14 17:50:46

by Trond Myklebust

[permalink] [raw]
Subject: Re: [PATCH] - [7/15] - remove defconfig ptr comparisons to 0 - fs/lockd


On Tue, 2007-11-13 at 23:45 -0500, Trond Myklebust wrote:
> On Wed, 2007-11-14 at 13:40 +1100, Neil Brown wrote:
> > On Tuesday November 13, [email protected] wrote:
> > > Remove defconfig ptr comparison to 0
> > >
> > > Remove sparse warning: Using plain integer as NULL pointer
> > >
> > > Signed-off-by: Joe Perches <[email protected]>
> > >
> > > ---
> > >
> > > diff --git a/fs/lockd/svcshare.c b/fs/lockd/svcshare.c
> > > index 068886d..98548ad 100644
> > > --- a/fs/lockd/svcshare.c
> > > +++ b/fs/lockd/svcshare.c
> > > @@ -71,7 +71,7 @@ nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
> > > struct nlm_share *share, **shpp;
> > > struct xdr_netobj *oh = &argp->lock.oh;
> > >
> > > - for (shpp = &file->f_shares; (share = *shpp) != 0; shpp = &share->s_next) {
> > > + for (shpp = &file->f_shares; (share = *shpp); shpp = &share->s_next) {
> > > if (share->s_host == host && nlm_cmp_owner(share, oh)) {
> > > *shpp = share->s_next;
> > > kfree(share);
> > >
> >
> > I particularly disagree with this change as it now looked like it
> > could be an '==' comparison that was mistyped. Making it
> > ....; (share = *shpp) != NULL; ....
>
> There would also be the minor fact that the original test is being
> inverted in this 'fix'. An accurate fix should at the very least be
> !(share = *shpp).

Apologies to Joe. I must have been tired when I typed the above. However
I'm still NACKing the patch: removing the '!= 0' altogether reduces code
legibility rather than improving it, particularly when we have that ugly
assignment.
If the intent is just to silence 'sparse', then replace with '!= NULL'.

> > makes the intent clear.
>
> It would be a lot cleaner just to pull the entire assignment out of the
> for() statement. IOW:
>
> for (shpp = &file->f_shares; *shpp != NULL; shpp = &(*shpp)->s_next) {
> struct nlm_share *share = *shpp;

...however doing something like the above would be altogether
preferable, since that cleans up the assignment which is the source of
the ugliness.

Cheers
Trond