diff mbox series

[2/3] 9pfs: Convert V9fsFidState::fid_list to QSIMPLEQ

Message ID 20210118142300.801516-3-groug@kaod.org (mailing list archive)
State New, archived
Headers show
Series 9pfs: Improve unreclaim logic | expand

Commit Message

Greg Kurz Jan. 18, 2021, 2:22 p.m. UTC
The fid_list is currently open-coded. This doesn't seem to serve any
purpose that cannot be met with QEMU's generic lists. Let's go for a
QSIMPLEQ : this will allow to add new fids at the end of the list and
to improve the logic in v9fs_mark_fids_unreclaim().

Signed-off-by: Greg Kurz <groug@kaod.org>
---
 hw/9pfs/9p.c | 41 ++++++++++++++++++-----------------------
 hw/9pfs/9p.h |  4 ++--
 2 files changed, 20 insertions(+), 25 deletions(-)

Comments

Christian Schoenebeck Jan. 19, 2021, 1:31 p.m. UTC | #1
On Montag, 18. Januar 2021 15:22:59 CET Greg Kurz wrote:
> The fid_list is currently open-coded. This doesn't seem to serve any
> purpose that cannot be met with QEMU's generic lists. Let's go for a
> QSIMPLEQ : this will allow to add new fids at the end of the list and
> to improve the logic in v9fs_mark_fids_unreclaim().
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>

In general LGTM hence:

Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

Some comments below ...

> ---
>  hw/9pfs/9p.c | 41 ++++++++++++++++++-----------------------
>  hw/9pfs/9p.h |  4 ++--
>  2 files changed, 20 insertions(+), 25 deletions(-)
> 
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 37c3379b7462..b65f320e6518 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -260,7 +260,7 @@ static V9fsFidState *coroutine_fn get_fid(V9fsPDU *pdu,
> int32_t fid) V9fsFidState *f;
>      V9fsState *s = pdu->s;
> 
> -    for (f = s->fid_list; f; f = f->next) {
> +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
>          BUG_ON(f->clunked);
>          if (f->fid == fid) {
>              /*
> @@ -295,7 +295,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> fid) {
>      V9fsFidState *f;
> 
> -    for (f = s->fid_list; f; f = f->next) {
> +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
>          /* If fid is already there return NULL */
>          BUG_ON(f->clunked);
>          if (f->fid == fid) {
> @@ -311,8 +311,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> fid) * reclaim won't close the file descriptor
>       */
>      f->flags |= FID_REFERENCED;
> -    f->next = s->fid_list;
> -    s->fid_list = f;
> +    QSIMPLEQ_INSERT_HEAD(&s->fid_list, f, next);

Not related to this series, but I wonder why queue.h wraps everything into:

do {
	...
} while (0);

No comment about it in git history. Looks like a leftover of its initial 
import from 2009.

>      v9fs_readdir_init(s->proto_version, &f->fs.dir);
>      v9fs_readdir_init(s->proto_version, &f->fs_reclaim.dir);
> @@ -401,20 +400,16 @@ static int coroutine_fn put_fid(V9fsPDU *pdu,
> V9fsFidState *fidp)
> 
>  static V9fsFidState *clunk_fid(V9fsState *s, int32_t fid)
>  {
> -    V9fsFidState **fidpp, *fidp;
> +    V9fsFidState *fidp;
> 
> -    for (fidpp = &s->fid_list; *fidpp; fidpp = &(*fidpp)->next) {
> -        if ((*fidpp)->fid == fid) {
> -            break;
> +    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
> +        if (fidp->fid == fid) {
> +            QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
> +            fidp->clunked = true;
> +            return fidp;
>          }
>      }
> -    if (*fidpp == NULL) {
> -        return NULL;
> -    }
> -    fidp = *fidpp;
> -    *fidpp = fidp->next;
> -    fidp->clunked = true;
> -    return fidp;
> +    return NULL;
>  }

Good cleanup there!

>  void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
> @@ -423,7 +418,7 @@ void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
>      V9fsState *s = pdu->s;
>      V9fsFidState *f, *reclaim_list = NULL;
> 
> -    for (f = s->fid_list; f; f = f->next) {
> +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
>          /*
>           * Unlink fids cannot be reclaimed. Check
>           * for them and skip them. Also skip fids
> @@ -505,7 +500,7 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU
> *pdu, V9fsPath *path) V9fsFidState *fidp;
> 
>  again:
> -    for (fidp = s->fid_list; fidp; fidp = fidp->next) {
> +    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
>          if (fidp->path.size != path->size) {
>              continue;
>          }
> @@ -537,13 +532,13 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu)
>      V9fsFidState *fidp;
> 
>      /* Free all fids */
> -    while (s->fid_list) {
> +    while (!QSIMPLEQ_EMPTY(&s->fid_list)) {
>          /* Get fid */
> -        fidp = s->fid_list;
> +        fidp = QSIMPLEQ_FIRST(&s->fid_list);
>          fidp->ref++;
> 
>          /* Clunk fid */
> -        s->fid_list = fidp->next;
> +        QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
>          fidp->clunked = true;
> 
>          put_fid(pdu, fidp);
> @@ -3121,7 +3116,7 @@ static int coroutine_fn v9fs_complete_rename(V9fsPDU
> *pdu, V9fsFidState *fidp, * Fixup fid's pointing to the old name to
>       * start pointing to the new name
>       */
> -    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
> +    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
>          if (v9fs_path_is_ancestor(&fidp->path, &tfidp->path)) {
>              /* replace the name */
>              v9fs_fix_path(&tfidp->path, &new_path,
> strlen(fidp->path.data)); @@ -3215,7 +3210,7 @@ static int coroutine_fn
> v9fs_fix_fid_paths(V9fsPDU *pdu, V9fsPath *olddir, * Fixup fid's pointing
> to the old name to
>       * start pointing to the new name
>       */
> -    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
> +    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
>          if (v9fs_path_is_ancestor(&oldpath, &tfidp->path)) {
>              /* replace the name */
>              v9fs_fix_path(&tfidp->path, &newpath, strlen(oldpath.data));
> @@ -4081,7 +4076,7 @@ int v9fs_device_realize_common(V9fsState *s, const
> V9fsTransport *t, s->ctx.fmode = fse->fmode;
>      s->ctx.dmode = fse->dmode;
> 
> -    s->fid_list = NULL;
> +    QSIMPLEQ_INIT(&s->fid_list);
>      qemu_co_rwlock_init(&s->rename_lock);
> 
>      if (s->ops->init(&s->ctx, errp) < 0) {
> diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
> index 93656323d1d7..85fb6930b0ca 100644
> --- a/hw/9pfs/9p.h
> +++ b/hw/9pfs/9p.h
> @@ -280,7 +280,7 @@ struct V9fsFidState {
>      uid_t uid;
>      int ref;
>      bool clunked;
> -    V9fsFidState *next;
> +    QSIMPLEQ_ENTRY(V9fsFidState) next;
>      V9fsFidState *rclm_lst;
>  };

Is there a reason for not migrating 'rclm_lst' as well?

Anyway, if you decide to do that as well, then it would IMO be fine with a 
separate patch later on, not worth making it more complicated with a v2 just 
for that.

> @@ -339,7 +339,7 @@ typedef struct {
>  struct V9fsState {
>      QLIST_HEAD(, V9fsPDU) free_list;
>      QLIST_HEAD(, V9fsPDU) active_list;
> -    V9fsFidState *fid_list;
> +    QSIMPLEQ_HEAD(, V9fsFidState) fid_list;

Not an issue for this series, but I wonder whether that macro's first argument 
shouldn't simply be dropped in queue.h, because there are only 2 occurences in 
the entire QEMU code base using it. It looks like nobody really needs it.

>      FileOperations *ops;
>      FsContext ctx;
>      char *tag;

Best regards,
Christian Schoenebeck
Greg Kurz Jan. 19, 2021, 2:34 p.m. UTC | #2
On Tue, 19 Jan 2021 14:31:26 +0100
Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:

> On Montag, 18. Januar 2021 15:22:59 CET Greg Kurz wrote:
> > The fid_list is currently open-coded. This doesn't seem to serve any
> > purpose that cannot be met with QEMU's generic lists. Let's go for a
> > QSIMPLEQ : this will allow to add new fids at the end of the list and
> > to improve the logic in v9fs_mark_fids_unreclaim().
> > 
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> 
> In general LGTM hence:
> 
> Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> 
> Some comments below ...
> 
> > ---
> >  hw/9pfs/9p.c | 41 ++++++++++++++++++-----------------------
> >  hw/9pfs/9p.h |  4 ++--
> >  2 files changed, 20 insertions(+), 25 deletions(-)
> > 
> > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> > index 37c3379b7462..b65f320e6518 100644
> > --- a/hw/9pfs/9p.c
> > +++ b/hw/9pfs/9p.c
> > @@ -260,7 +260,7 @@ static V9fsFidState *coroutine_fn get_fid(V9fsPDU *pdu,
> > int32_t fid) V9fsFidState *f;
> >      V9fsState *s = pdu->s;
> > 
> > -    for (f = s->fid_list; f; f = f->next) {
> > +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
> >          BUG_ON(f->clunked);
> >          if (f->fid == fid) {
> >              /*
> > @@ -295,7 +295,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> > fid) {
> >      V9fsFidState *f;
> > 
> > -    for (f = s->fid_list; f; f = f->next) {
> > +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
> >          /* If fid is already there return NULL */
> >          BUG_ON(f->clunked);
> >          if (f->fid == fid) {
> > @@ -311,8 +311,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> > fid) * reclaim won't close the file descriptor
> >       */
> >      f->flags |= FID_REFERENCED;
> > -    f->next = s->fid_list;
> > -    s->fid_list = f;
> > +    QSIMPLEQ_INSERT_HEAD(&s->fid_list, f, next);
> 
> Not related to this series, but I wonder why queue.h wraps everything into:
> 
> do {
> 	...
> } while (0);
> 

Note, this is do { ... } while (0) *without* the trailing semi-colon, which
is the corner stone of this trick.

> No comment about it in git history. Looks like a leftover of its initial 
> import from 2009.
> 

This is the usual way to define multi-statement macros. More details here:

http://c-faq.com/cpp/multistmt.html

> >      v9fs_readdir_init(s->proto_version, &f->fs.dir);
> >      v9fs_readdir_init(s->proto_version, &f->fs_reclaim.dir);
> > @@ -401,20 +400,16 @@ static int coroutine_fn put_fid(V9fsPDU *pdu,
> > V9fsFidState *fidp)
> > 
> >  static V9fsFidState *clunk_fid(V9fsState *s, int32_t fid)
> >  {
> > -    V9fsFidState **fidpp, *fidp;
> > +    V9fsFidState *fidp;
> > 
> > -    for (fidpp = &s->fid_list; *fidpp; fidpp = &(*fidpp)->next) {
> > -        if ((*fidpp)->fid == fid) {
> > -            break;
> > +    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
> > +        if (fidp->fid == fid) {
> > +            QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
> > +            fidp->clunked = true;
> > +            return fidp;
> >          }
> >      }
> > -    if (*fidpp == NULL) {
> > -        return NULL;
> > -    }
> > -    fidp = *fidpp;
> > -    *fidpp = fidp->next;
> > -    fidp->clunked = true;
> > -    return fidp;
> > +    return NULL;
> >  }
> 
> Good cleanup there!
> 

Thanks !

> >  void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
> > @@ -423,7 +418,7 @@ void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
> >      V9fsState *s = pdu->s;
> >      V9fsFidState *f, *reclaim_list = NULL;
> > 
> > -    for (f = s->fid_list; f; f = f->next) {
> > +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
> >          /*
> >           * Unlink fids cannot be reclaimed. Check
> >           * for them and skip them. Also skip fids
> > @@ -505,7 +500,7 @@ static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU
> > *pdu, V9fsPath *path) V9fsFidState *fidp;
> > 
> >  again:
> > -    for (fidp = s->fid_list; fidp; fidp = fidp->next) {
> > +    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
> >          if (fidp->path.size != path->size) {
> >              continue;
> >          }
> > @@ -537,13 +532,13 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu)
> >      V9fsFidState *fidp;
> > 
> >      /* Free all fids */
> > -    while (s->fid_list) {
> > +    while (!QSIMPLEQ_EMPTY(&s->fid_list)) {
> >          /* Get fid */
> > -        fidp = s->fid_list;
> > +        fidp = QSIMPLEQ_FIRST(&s->fid_list);
> >          fidp->ref++;
> > 
> >          /* Clunk fid */
> > -        s->fid_list = fidp->next;
> > +        QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
> >          fidp->clunked = true;
> > 
> >          put_fid(pdu, fidp);
> > @@ -3121,7 +3116,7 @@ static int coroutine_fn v9fs_complete_rename(V9fsPDU
> > *pdu, V9fsFidState *fidp, * Fixup fid's pointing to the old name to
> >       * start pointing to the new name
> >       */
> > -    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
> > +    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
> >          if (v9fs_path_is_ancestor(&fidp->path, &tfidp->path)) {
> >              /* replace the name */
> >              v9fs_fix_path(&tfidp->path, &new_path,
> > strlen(fidp->path.data)); @@ -3215,7 +3210,7 @@ static int coroutine_fn
> > v9fs_fix_fid_paths(V9fsPDU *pdu, V9fsPath *olddir, * Fixup fid's pointing
> > to the old name to
> >       * start pointing to the new name
> >       */
> > -    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
> > +    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
> >          if (v9fs_path_is_ancestor(&oldpath, &tfidp->path)) {
> >              /* replace the name */
> >              v9fs_fix_path(&tfidp->path, &newpath, strlen(oldpath.data));
> > @@ -4081,7 +4076,7 @@ int v9fs_device_realize_common(V9fsState *s, const
> > V9fsTransport *t, s->ctx.fmode = fse->fmode;
> >      s->ctx.dmode = fse->dmode;
> > 
> > -    s->fid_list = NULL;
> > +    QSIMPLEQ_INIT(&s->fid_list);
> >      qemu_co_rwlock_init(&s->rename_lock);
> > 
> >      if (s->ops->init(&s->ctx, errp) < 0) {
> > diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
> > index 93656323d1d7..85fb6930b0ca 100644
> > --- a/hw/9pfs/9p.h
> > +++ b/hw/9pfs/9p.h
> > @@ -280,7 +280,7 @@ struct V9fsFidState {
> >      uid_t uid;
> >      int ref;
> >      bool clunked;
> > -    V9fsFidState *next;
> > +    QSIMPLEQ_ENTRY(V9fsFidState) next;
> >      V9fsFidState *rclm_lst;
> >  };
> 
> Is there a reason for not migrating 'rclm_lst' as well?
> 

Yeah. I did consider doing so at first but these were
too many changes. Also, the fid list and the reclaim
list have quite different needs, that each deserve its
own patch.

> Anyway, if you decide to do that as well, then it would IMO be fine with a 
> separate patch later on, not worth making it more complicated with a v2 just 
> for that.

Yes, I already have a patch to convert the reclaim list to QSLIST.
I'll post it later as it is merely cosmetic, while this series
changes the behavior.

> > @@ -339,7 +339,7 @@ typedef struct {
> >  struct V9fsState {
> >      QLIST_HEAD(, V9fsPDU) free_list;
> >      QLIST_HEAD(, V9fsPDU) active_list;
> > -    V9fsFidState *fid_list;
> > +    QSIMPLEQ_HEAD(, V9fsFidState) fid_list;
> 
> Not an issue for this series, but I wonder whether that macro's first argument 
> shouldn't simply be dropped in queue.h, because there are only 2 occurences in 
> the entire QEMU code base using it. It looks like nobody really needs it.
> 

A similar macro exist for the other list types as well, with some more
users. If we go for such a change, I think this should stay consistent
accros list types. All users should hence be audited first.

> >      FileOperations *ops;
> >      FsContext ctx;
> >      char *tag;
> 
> Best regards,
> Christian Schoenebeck
> 
>
Christian Schoenebeck Jan. 19, 2021, 3:28 p.m. UTC | #3
On Dienstag, 19. Januar 2021 15:34:07 CET Greg Kurz wrote:
> On Tue, 19 Jan 2021 14:31:26 +0100
> 
> Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:
> > On Montag, 18. Januar 2021 15:22:59 CET Greg Kurz wrote:
> > > The fid_list is currently open-coded. This doesn't seem to serve any
> > > purpose that cannot be met with QEMU's generic lists. Let's go for a
> > > QSIMPLEQ : this will allow to add new fids at the end of the list and
> > > to improve the logic in v9fs_mark_fids_unreclaim().
> > > 
> > > Signed-off-by: Greg Kurz <groug@kaod.org>
> > 
> > In general LGTM hence:
> > 
> > Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> > 
> > Some comments below ...
> > 
> > > ---
> > > 
> > >  hw/9pfs/9p.c | 41 ++++++++++++++++++-----------------------
> > >  hw/9pfs/9p.h |  4 ++--
> > >  2 files changed, 20 insertions(+), 25 deletions(-)
> > > 
> > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> > > index 37c3379b7462..b65f320e6518 100644
> > > --- a/hw/9pfs/9p.c
> > > +++ b/hw/9pfs/9p.c
> > > @@ -260,7 +260,7 @@ static V9fsFidState *coroutine_fn get_fid(V9fsPDU
> > > *pdu,
> > > int32_t fid) V9fsFidState *f;
> > > 
> > >      V9fsState *s = pdu->s;
> > > 
> > > -    for (f = s->fid_list; f; f = f->next) {
> > > +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
> > > 
> > >          BUG_ON(f->clunked);
> > >          if (f->fid == fid) {
> > >          
> > >              /*
> > > 
> > > @@ -295,7 +295,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> > > fid) {
> > > 
> > >      V9fsFidState *f;
> > > 
> > > -    for (f = s->fid_list; f; f = f->next) {
> > > +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
> > > 
> > >          /* If fid is already there return NULL */
> > >          BUG_ON(f->clunked);
> > >          if (f->fid == fid) {
> > > 
> > > @@ -311,8 +311,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> > > fid) * reclaim won't close the file descriptor
> > > 
> > >       */
> > >      
> > >      f->flags |= FID_REFERENCED;
> > > 
> > > -    f->next = s->fid_list;
> > > -    s->fid_list = f;
> > > +    QSIMPLEQ_INSERT_HEAD(&s->fid_list, f, next);
> > 
> > Not related to this series, but I wonder why queue.h wraps everything
> > into:
> > 
> > do {
> > 
> > 	...
> > 
> > } while (0);
> 
> Note, this is do { ... } while (0) *without* the trailing semi-colon, which
> is the corner stone of this trick.

Yes, I got that. What I meant was, unless I am missing something, a simple 
compound statement (without trailing semi-colon) a.k.a. a 'block' is the more 
common way to handle this, like:

#define QSIMPLEQ_INIT(head) {                                        \
    (head)->sqh_first = NULL;                                        \
    (head)->sqh_last = &(head)->sqh_first;                           \
}

Third patch tomorrow ... thanks Greg!

Best regards,
Christian Schoenebeck
Greg Kurz Jan. 19, 2021, 5:23 p.m. UTC | #4
On Tue, 19 Jan 2021 16:28:01 +0100
Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:

> On Dienstag, 19. Januar 2021 15:34:07 CET Greg Kurz wrote:
> > On Tue, 19 Jan 2021 14:31:26 +0100
> > 
> > Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:
> > > On Montag, 18. Januar 2021 15:22:59 CET Greg Kurz wrote:
> > > > The fid_list is currently open-coded. This doesn't seem to serve any
> > > > purpose that cannot be met with QEMU's generic lists. Let's go for a
> > > > QSIMPLEQ : this will allow to add new fids at the end of the list and
> > > > to improve the logic in v9fs_mark_fids_unreclaim().
> > > > 
> > > > Signed-off-by: Greg Kurz <groug@kaod.org>
> > > 
> > > In general LGTM hence:
> > > 
> > > Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> > > 
> > > Some comments below ...
> > > 
> > > > ---
> > > > 
> > > >  hw/9pfs/9p.c | 41 ++++++++++++++++++-----------------------
> > > >  hw/9pfs/9p.h |  4 ++--
> > > >  2 files changed, 20 insertions(+), 25 deletions(-)
> > > > 
> > > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> > > > index 37c3379b7462..b65f320e6518 100644
> > > > --- a/hw/9pfs/9p.c
> > > > +++ b/hw/9pfs/9p.c
> > > > @@ -260,7 +260,7 @@ static V9fsFidState *coroutine_fn get_fid(V9fsPDU
> > > > *pdu,
> > > > int32_t fid) V9fsFidState *f;
> > > > 
> > > >      V9fsState *s = pdu->s;
> > > > 
> > > > -    for (f = s->fid_list; f; f = f->next) {
> > > > +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
> > > > 
> > > >          BUG_ON(f->clunked);
> > > >          if (f->fid == fid) {
> > > >          
> > > >              /*
> > > > 
> > > > @@ -295,7 +295,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> > > > fid) {
> > > > 
> > > >      V9fsFidState *f;
> > > > 
> > > > -    for (f = s->fid_list; f; f = f->next) {
> > > > +    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
> > > > 
> > > >          /* If fid is already there return NULL */
> > > >          BUG_ON(f->clunked);
> > > >          if (f->fid == fid) {
> > > > 
> > > > @@ -311,8 +311,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t
> > > > fid) * reclaim won't close the file descriptor
> > > > 
> > > >       */
> > > >      
> > > >      f->flags |= FID_REFERENCED;
> > > > 
> > > > -    f->next = s->fid_list;
> > > > -    s->fid_list = f;
> > > > +    QSIMPLEQ_INSERT_HEAD(&s->fid_list, f, next);
> > > 
> > > Not related to this series, but I wonder why queue.h wraps everything
> > > into:
> > > 
> > > do {
> > > 
> > > 	...
> > > 
> > > } while (0);
> > 
> > Note, this is do { ... } while (0) *without* the trailing semi-colon, which
> > is the corner stone of this trick.
> 
> Yes, I got that. What I meant was, unless I am missing something, a simple 
> compound statement (without trailing semi-colon) a.k.a. a 'block' is the more 
> common way to handle this, like:
> 
> #define QSIMPLEQ_INIT(head) {                                        \
>     (head)->sqh_first = NULL;                                        \
>     (head)->sqh_last = &(head)->sqh_first;                           \
> }
> 

No this isn't the more common way because it doesn't work with
if...else statements, i.e.

    if (some_condition)
        QSIMPLEQ_INIT(&head);
    else
	do_some_other_stuff()

has illagal syntax because of the semi-colon.

Of course, since the QEMU coding styles mandates { } in if...else
statements, your suggestion should just work, but do { } while(0)
doesn't do harm (compilers optimize that flawlessly) and it is
so commonly used elsewhere that I don't think its worth changing.

> Third patch tomorrow ... thanks Greg!
> 
> Best regards,
> Christian Schoenebeck
> 
>
diff mbox series

Patch

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 37c3379b7462..b65f320e6518 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -260,7 +260,7 @@  static V9fsFidState *coroutine_fn get_fid(V9fsPDU *pdu, int32_t fid)
     V9fsFidState *f;
     V9fsState *s = pdu->s;
 
-    for (f = s->fid_list; f; f = f->next) {
+    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
         BUG_ON(f->clunked);
         if (f->fid == fid) {
             /*
@@ -295,7 +295,7 @@  static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
 {
     V9fsFidState *f;
 
-    for (f = s->fid_list; f; f = f->next) {
+    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
         /* If fid is already there return NULL */
         BUG_ON(f->clunked);
         if (f->fid == fid) {
@@ -311,8 +311,7 @@  static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
      * reclaim won't close the file descriptor
      */
     f->flags |= FID_REFERENCED;
-    f->next = s->fid_list;
-    s->fid_list = f;
+    QSIMPLEQ_INSERT_HEAD(&s->fid_list, f, next);
 
     v9fs_readdir_init(s->proto_version, &f->fs.dir);
     v9fs_readdir_init(s->proto_version, &f->fs_reclaim.dir);
@@ -401,20 +400,16 @@  static int coroutine_fn put_fid(V9fsPDU *pdu, V9fsFidState *fidp)
 
 static V9fsFidState *clunk_fid(V9fsState *s, int32_t fid)
 {
-    V9fsFidState **fidpp, *fidp;
+    V9fsFidState *fidp;
 
-    for (fidpp = &s->fid_list; *fidpp; fidpp = &(*fidpp)->next) {
-        if ((*fidpp)->fid == fid) {
-            break;
+    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
+        if (fidp->fid == fid) {
+            QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
+            fidp->clunked = true;
+            return fidp;
         }
     }
-    if (*fidpp == NULL) {
-        return NULL;
-    }
-    fidp = *fidpp;
-    *fidpp = fidp->next;
-    fidp->clunked = true;
-    return fidp;
+    return NULL;
 }
 
 void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
@@ -423,7 +418,7 @@  void coroutine_fn v9fs_reclaim_fd(V9fsPDU *pdu)
     V9fsState *s = pdu->s;
     V9fsFidState *f, *reclaim_list = NULL;
 
-    for (f = s->fid_list; f; f = f->next) {
+    QSIMPLEQ_FOREACH(f, &s->fid_list, next) {
         /*
          * Unlink fids cannot be reclaimed. Check
          * for them and skip them. Also skip fids
@@ -505,7 +500,7 @@  static int coroutine_fn v9fs_mark_fids_unreclaim(V9fsPDU *pdu, V9fsPath *path)
     V9fsFidState *fidp;
 
 again:
-    for (fidp = s->fid_list; fidp; fidp = fidp->next) {
+    QSIMPLEQ_FOREACH(fidp, &s->fid_list, next) {
         if (fidp->path.size != path->size) {
             continue;
         }
@@ -537,13 +532,13 @@  static void coroutine_fn virtfs_reset(V9fsPDU *pdu)
     V9fsFidState *fidp;
 
     /* Free all fids */
-    while (s->fid_list) {
+    while (!QSIMPLEQ_EMPTY(&s->fid_list)) {
         /* Get fid */
-        fidp = s->fid_list;
+        fidp = QSIMPLEQ_FIRST(&s->fid_list);
         fidp->ref++;
 
         /* Clunk fid */
-        s->fid_list = fidp->next;
+        QSIMPLEQ_REMOVE(&s->fid_list, fidp, V9fsFidState, next);
         fidp->clunked = true;
 
         put_fid(pdu, fidp);
@@ -3121,7 +3116,7 @@  static int coroutine_fn v9fs_complete_rename(V9fsPDU *pdu, V9fsFidState *fidp,
      * Fixup fid's pointing to the old name to
      * start pointing to the new name
      */
-    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
+    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
         if (v9fs_path_is_ancestor(&fidp->path, &tfidp->path)) {
             /* replace the name */
             v9fs_fix_path(&tfidp->path, &new_path, strlen(fidp->path.data));
@@ -3215,7 +3210,7 @@  static int coroutine_fn v9fs_fix_fid_paths(V9fsPDU *pdu, V9fsPath *olddir,
      * Fixup fid's pointing to the old name to
      * start pointing to the new name
      */
-    for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
+    QSIMPLEQ_FOREACH(tfidp, &s->fid_list, next) {
         if (v9fs_path_is_ancestor(&oldpath, &tfidp->path)) {
             /* replace the name */
             v9fs_fix_path(&tfidp->path, &newpath, strlen(oldpath.data));
@@ -4081,7 +4076,7 @@  int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t,
     s->ctx.fmode = fse->fmode;
     s->ctx.dmode = fse->dmode;
 
-    s->fid_list = NULL;
+    QSIMPLEQ_INIT(&s->fid_list);
     qemu_co_rwlock_init(&s->rename_lock);
 
     if (s->ops->init(&s->ctx, errp) < 0) {
diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
index 93656323d1d7..85fb6930b0ca 100644
--- a/hw/9pfs/9p.h
+++ b/hw/9pfs/9p.h
@@ -280,7 +280,7 @@  struct V9fsFidState {
     uid_t uid;
     int ref;
     bool clunked;
-    V9fsFidState *next;
+    QSIMPLEQ_ENTRY(V9fsFidState) next;
     V9fsFidState *rclm_lst;
 };
 
@@ -339,7 +339,7 @@  typedef struct {
 struct V9fsState {
     QLIST_HEAD(, V9fsPDU) free_list;
     QLIST_HEAD(, V9fsPDU) active_list;
-    V9fsFidState *fid_list;
+    QSIMPLEQ_HEAD(, V9fsFidState) fid_list;
     FileOperations *ops;
     FsContext ctx;
     char *tag;