[2/6] hw/9pfs: Don't free fid in clunk

On interrupted syscall on client we can end up having fid
being acted upon by glib pool but still get a clunk request on that

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 hw/9pfs/virtio-9p.c |  139 +++++++++++++++++++++++++++-----------------------
 hw/9pfs/virtio-9p.h |    7 +--
 2 files changed, 76 insertions(+), 70 deletions(-)

On 06/06/2011 10:16 AM, Aneesh Kumar K.V wrote:
> On interrupted syscall on client we can end up having fid
> being acted upon by glib pool but still get a clunk request on that

Couple of comments below.

- JV

> Signed-off-by: Aneesh Kumar K.V<aneesh.kumar@linux.vnet.ibm.com>
> ---
>   hw/9pfs/virtio-9p.c |  139 +++++++++++++++++++++++++++-----------------------
>   hw/9pfs/virtio-9p.h |    7 +--
>   2 files changed, 76 insertions(+), 70 deletions(-)
>
> diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
> index 03d8664..f3127a5 100644
> --- a/hw/9pfs/virtio-9p.c
> +++ b/hw/9pfs/virtio-9p.c
> @@ -237,12 +237,11 @@ static V9fsFidState *get_fid(V9fsState *s, int32_t fid)
>       V9fsFidState *f;
>
>       for (f = s->fid_list; f; f = f->next) {
> -        if (f->fid == fid) {
> +        if (f->fid == fid&&  !f->clunked) {
>               f->ref++;
>               return f;
>           }
>       }
> -
>       return NULL;
>   }
>
> @@ -250,12 +249,12 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
>   {
>       V9fsFidState *f;
>
> -    f = get_fid(s, fid);
> -    if (f) {
> -        f->ref--;
> -        return NULL;
> +    for (f = s->fid_list; f; f = f->next) {
> +        /* If fid is already there return NULL */
> +        if (f->fid == fid&&  !f->clunked) {
> +            return NULL;
> +        }
>       }
> -
>       f = qemu_mallocz(sizeof(V9fsFidState));
Memory leak if we find a cluncked fid here?
More than that how do you handle this?
>       f->fid = fid;
>       f->fid_type = P9_FID_NONE;
> @@ -300,9 +299,33 @@ free_value:
>       return retval;
>   }
>
> -static int free_fid(V9fsState *s, int32_t fid)
> +static int release_fid(V9fsState *s, V9fsFidState *fidp)
>   {
>       int retval = 0;
> +
> +    if (fidp->fid_type == P9_FID_FILE) {
> +        retval = v9fs_co_close(s, fidp);
> +    } else if (fidp->fid_type == P9_FID_DIR) {
> +        retval = v9fs_co_closedir(s, fidp);
> +    } else if (fidp->fid_type == P9_FID_XATTR) {
> +        retval = v9fs_xattr_fid_clunk(s, fidp);
> +    }
> +    v9fs_string_free(&fidp->path);
> +    qemu_free(fidp);
> +    return retval;
> +}
> +
> +static void put_fid(V9fsState *s, V9fsFidState *fidp)
> +{
> +    BUG_ON(!fidp->ref);
> +    fidp->ref--;
> +    if (!fidp->ref&&  fidp->clunked) {
> +        release_fid(s, fidp);
> +    }
> +}
> +
> +static int free_fid(V9fsState *s, int32_t fid)
With the changed semantics; I would suggest you to swap the names of
release_fid() and free_fid()

Or even better
free_fid() -> clunk_fid()
release_fid() -> free_fid()
> +{
>       V9fsFidState **fidpp, *fidp;
>
>       for (fidpp =&s->fid_list; *fidpp; fidpp =&(*fidpp)->next) {
> @@ -314,20 +337,10 @@ static int free_fid(V9fsState *s, int32_t fid)
>       if (*fidpp == NULL) {
>           return -ENOENT;
>       }
> -
>       fidp = *fidpp;
>       *fidpp = fidp->next;
> -
> -    if (fidp->fid_type == P9_FID_FILE) {
> -        retval = v9fs_co_close(s, fidp);
> -    } else if (fidp->fid_type == P9_FID_DIR) {
> -        retval = v9fs_co_closedir(s, fidp);
> -    } else if (fidp->fid_type == P9_FID_XATTR) {
> -        retval = v9fs_xattr_fid_clunk(s, fidp);
> -    }
> -    v9fs_string_free(&fidp->path);
> -    qemu_free(fidp);
> -    return retval;
> +    fidp->clunked = 1;
> +    return 0;
>   }
>
>   #define P9_QID_TYPE_DIR         0x80
> @@ -1022,14 +1035,13 @@ static void v9fs_attach(void *opaque)
>       err = fid_to_qid(s, fidp,&qid);
>       if (err<  0) {
>           err = -EINVAL;
> -        put_fid(fidp);
>           free_fid(s, fid);
> -        goto out_nofid;
> +        goto out;
>       }
>       offset += pdu_marshal(pdu, offset, "Q",&qid);
>       err = offset;
> -    put_fid(fidp);
> -
> +out:
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>       v9fs_string_free(&uname);
> @@ -1066,7 +1078,7 @@ static void v9fs_stat(void *opaque)
>       err = offset;
>       v9fs_stat_free(&v9stat);
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>   }
> @@ -1102,7 +1114,7 @@ static void v9fs_getattr(void *opaque)
>       retval = offset;
>       retval += pdu_marshal(pdu, offset, "A",&v9stat_dotl);
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, retval);
>   }
> @@ -1196,7 +1208,7 @@ static void v9fs_setattr(void *opaque)
>       }
>       err = offset;
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>   }
> @@ -1279,9 +1291,7 @@ static void v9fs_walk(void *opaque)
>               v9fs_string_copy(&newfidp->path,&path);
>               err = v9fs_co_lstat(s,&newfidp->path,&stbuf);
>               if (err<  0) {
> -                put_fid(newfidp);
>                   free_fid(s, newfidp->fid);
> -                newfidp = NULL;
>                   v9fs_string_free(&path);
>                   goto out;
>               }
> @@ -1291,9 +1301,9 @@ static void v9fs_walk(void *opaque)
>       }
>       err = v9fs_walk_marshal(pdu, nwnames, qids);
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>       if (newfidp) {
> -        put_fid(newfidp);
> +        put_fid(s, newfidp);
>       }
>   out_nofid:
>       complete_pdu(s, pdu, err);
> @@ -1383,7 +1393,7 @@ static void v9fs_open(void *opaque)
>           err = offset;
>       }
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>   }
> @@ -1437,7 +1447,7 @@ static void v9fs_lcreate(void *opaque)
>       offset += pdu_marshal(pdu, offset, "Qd",&qid, iounit);
>       err = offset;
>   out:
> -    put_fid(fidp);
> +    put_fid(pdu->s, fidp);
>   out_nofid:
>       complete_pdu(pdu->s, pdu, err);
>       v9fs_string_free(&name);
> @@ -1465,7 +1475,7 @@ static void v9fs_fsync(void *opaque)
>           err = offset;
>       }
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>       complete_pdu(s, pdu, err);
>   }
>
> @@ -1474,16 +1484,25 @@ static void v9fs_clunk(void *opaque)
>       int err;
>       int32_t fid;
>       size_t offset = 7;
> +    V9fsFidState *fidp;
>       V9fsPDU *pdu = opaque;
>       V9fsState *s = pdu->s;
>
>       pdu_unmarshal(pdu, offset, "d",&fid);
> -    err = free_fid(s, fid);
> +
> +    fidp = get_fid(s, fid);
> +    if (fidp == NULL) {
> +        err = -ENOENT;
> +        goto out_nofid;
> +    }
> +    err = free_fid(s, fidp->fid);
>       if (err<  0) {
>           goto out;
>       }
>       err = offset;
>   out:
> +    put_fid(s, fidp);
> +out_nofid:
>       complete_pdu(s, pdu, err);
>   }
>
> @@ -1638,7 +1657,7 @@ static void v9fs_read(void *opaque)
>           err = -EINVAL;
>       }
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>   }
> @@ -1747,7 +1766,7 @@ static void v9fs_readdir(void *opaque)
>       retval += pdu_marshal(pdu, offset, "d", count);
>       retval += count;
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, retval);
>   }
> @@ -1857,7 +1876,7 @@ static void v9fs_write(void *opaque)
>       offset += pdu_marshal(pdu, offset, "d", total);
>       err = offset;
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>   }
> @@ -1923,10 +1942,10 @@ static void v9fs_create(void *opaque)
>           }
>           err = v9fs_co_link(pdu->s,&nfidp->path,&fullname);
>           if (err<  0) {
> -            put_fid(nfidp);
> +            put_fid(pdu->s, nfidp);
>               goto out;
>           }
> -        put_fid(nfidp);
> +        put_fid(pdu->s, nfidp);
>       } else if (perm&  P9_STAT_MODE_DEVICE) {
>           char ctype;
>           uint32_t major, minor;
> @@ -1990,7 +2009,7 @@ static void v9fs_create(void *opaque)
>       err = offset;
>
>   out:
> -    put_fid(fidp);
> +    put_fid(pdu->s, fidp);
>   out_nofid:
>      complete_pdu(pdu->s, pdu, err);
>      v9fs_string_free(&name);
> @@ -2035,7 +2054,7 @@ static void v9fs_symlink(void *opaque)
>       offset += pdu_marshal(pdu, offset, "Q",&qid);
>       err = offset;
>   out:
> -    put_fid(dfidp);
> +    put_fid(pdu->s, dfidp);
>   out_nofid:
>       complete_pdu(pdu->s, pdu, err);
>       v9fs_string_free(&name);
> @@ -2086,7 +2105,7 @@ static void v9fs_link(void *opaque)
>       v9fs_string_free(&fullname);
>
>   out:
> -    put_fid(dfidp);
> +    put_fid(s, dfidp);
>   out_nofid:
>       v9fs_string_free(&name);
>       complete_pdu(s, pdu, err);
> @@ -2113,8 +2132,8 @@ static void v9fs_remove(void *opaque)
>       }
>
>       /* For TREMOVE we need to clunk the fid even on failed remove */
> -    put_fid(fidp);
>       free_fid(pdu->s, fidp->fid);
> +    put_fid(pdu->s, fidp);
>   out_nofid:
>       complete_pdu(pdu->s, pdu, err);
>   }
> @@ -2185,7 +2204,7 @@ static int v9fs_complete_rename(V9fsState *s, V9fsFidState *fidp,
>       }
>   out:
>       if (dirfidp) {
> -        put_fid(dirfidp);
> +        put_fid(s, dirfidp);
>       }
>   out_nofid:
>       return err;
> @@ -2216,7 +2235,7 @@ static void v9fs_rename(void *opaque)
>           err = offset;
>       }
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>       v9fs_string_free(&name);
> @@ -2305,7 +2324,7 @@ static void v9fs_wstat(void *opaque)
>       }
>       err = offset;
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       v9fs_stat_free(&v9stat);
>       complete_pdu(s, pdu, err);
> @@ -2379,7 +2398,7 @@ static void v9fs_statfs(void *opaque)
>       retval = offset;
>       retval += v9fs_fill_statfs(s, pdu,&stbuf);
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, retval);
>       return;
> @@ -2425,7 +2444,7 @@ static void v9fs_mknod(void *opaque)
>       err = offset;
>       err += pdu_marshal(pdu, offset, "Q",&qid);
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>       v9fs_string_free(&fullname);
> @@ -2473,7 +2492,7 @@ static void v9fs_lock(void *opaque)
>       }
>       status = P9_LOCK_SUCCESS;
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       err = offset;
>       err += pdu_marshal(pdu, offset, "b", status);
> @@ -2515,7 +2534,7 @@ static void v9fs_getlock(void *opaque)
>                             &glock->client_id);
>       err = offset;
>   out:
> -    put_fid(fidp);
> +    put_fid(s, fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>       qemu_free(glock);
> @@ -2555,7 +2574,7 @@ static void v9fs_mkdir(void *opaque)
>       offset += pdu_marshal(pdu, offset, "Q",&qid);
>       err = offset;
>   out:
> -    put_fid(fidp);
> +    put_fid(pdu->s, fidp);
>   out_nofid:
>       complete_pdu(pdu->s, pdu, err);
>       v9fs_string_free(&fullname);
> @@ -2593,9 +2612,7 @@ static void v9fs_xattrwalk(void *opaque)
>           size = v9fs_co_llistxattr(s,&xattr_fidp->path, NULL, 0);
>           if (size<  0) {
>               err = size;
> -            put_fid(xattr_fidp);
>               free_fid(s, xattr_fidp->fid);
> -            xattr_fidp = NULL;
>               goto out;
>           }
>           /*
> @@ -2610,9 +2627,7 @@ static void v9fs_xattrwalk(void *opaque)
>                                        xattr_fidp->fs.xattr.value,
>                                        xattr_fidp->fs.xattr.len);
>               if (err<  0) {
> -                put_fid(xattr_fidp);
>                   free_fid(s, xattr_fidp->fid);
> -                xattr_fidp = NULL;
>                   goto out;
>               }
>           }
> @@ -2627,9 +2642,7 @@ static void v9fs_xattrwalk(void *opaque)
>                                    &name, NULL, 0);
>           if (size<  0) {
>               err = size;
> -            put_fid(xattr_fidp);
>               free_fid(s, xattr_fidp->fid);
> -            xattr_fidp = NULL;
>               goto out;
>           }
>           /*
> @@ -2644,9 +2657,7 @@ static void v9fs_xattrwalk(void *opaque)
>                                       &name, xattr_fidp->fs.xattr.value,
>                                       xattr_fidp->fs.xattr.len);
>               if (err<  0) {
> -                put_fid(xattr_fidp);
>                   free_fid(s, xattr_fidp->fid);
> -                xattr_fidp = NULL;
>                   goto out;
>               }
>           }
> @@ -2654,9 +2665,9 @@ static void v9fs_xattrwalk(void *opaque)
>           err = offset;
>       }
>   out:
> -    put_fid(file_fidp);
> +    put_fid(s, file_fidp);
>       if (xattr_fidp) {
> -        put_fid(xattr_fidp);
> +        put_fid(s, xattr_fidp);
>       }
>   out_nofid:
>       complete_pdu(s, pdu, err);
> @@ -2698,7 +2709,7 @@ static void v9fs_xattrcreate(void *opaque)
>           xattr_fidp->fs.xattr.value = NULL;
>       }
>       err = offset;
> -    put_fid(file_fidp);
> +    put_fid(s, file_fidp);
>   out_nofid:
>       complete_pdu(s, pdu, err);
>       v9fs_string_free(&name);
> @@ -2729,7 +2740,7 @@ static void v9fs_readlink(void *opaque)
>       err = offset;
>       v9fs_string_free(&target);
>   out:
> -    put_fid(fidp);
> +    put_fid(pdu->s, fidp);
>   out_nofid:
>       complete_pdu(pdu->s, pdu, err);
>   }
> diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
> index ce93c20..e16e5f4 100644
> --- a/hw/9pfs/virtio-9p.h
> +++ b/hw/9pfs/virtio-9p.h
> @@ -204,6 +204,7 @@ struct V9fsFidState
>       } fs;
>       uid_t uid;
>       int ref;
> +    int clunked;
>       V9fsFidState *next;
>   };
>
> @@ -362,11 +363,5 @@ static inline size_t do_pdu_unpack(void *dst, struct iovec *sg, int sg_count,
>       return pdu_packunpack(dst, sg, sg_count, offset, size, 0);
>   }
>
> -static inline void put_fid(V9fsFidState *fidp)
> -{
> -    BUG_ON(!fidp->ref);
> -    fidp->ref--;
> -}
> -
>   extern void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq);
>   #endif

On Thu, 09 Jun 2011 17:27:00 -0700, Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com> wrote:
> On 06/06/2011 10:16 AM, Aneesh Kumar K.V wrote:
> > On interrupted syscall on client we can end up having fid
> > being acted upon by glib pool but still get a clunk request on that
> 
> Couple of comments below.
> 
> - JV
> 
> > Signed-off-by: Aneesh Kumar K.V<aneesh.kumar@linux.vnet.ibm.com>
> > ---
> >   hw/9pfs/virtio-9p.c |  139 +++++++++++++++++++++++++++-----------------------
> >   hw/9pfs/virtio-9p.h |    7 +--
> >   2 files changed, 76 insertions(+), 70 deletions(-)
> >
> > diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
> > index 03d8664..f3127a5 100644
> > --- a/hw/9pfs/virtio-9p.c
> > +++ b/hw/9pfs/virtio-9p.c
> > @@ -237,12 +237,11 @@ static V9fsFidState *get_fid(V9fsState *s, int32_t fid)
> >       V9fsFidState *f;
> >
> >       for (f = s->fid_list; f; f = f->next) {
> > -        if (f->fid == fid) {
> > +        if (f->fid == fid&&  !f->clunked) {
> >               f->ref++;
> >               return f;
> >           }
> >       }
> > -
> >       return NULL;
> >   }
> >
> > @@ -250,12 +249,12 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
> >   {
> >       V9fsFidState *f;
> >
> > -    f = get_fid(s, fid);
> > -    if (f) {
> > -        f->ref--;
> > -        return NULL;
> > +    for (f = s->fid_list; f; f = f->next) {
> > +        /* If fid is already there return NULL */
> > +        if (f->fid == fid&&  !f->clunked) {
> > +            return NULL;
> > +        }
> >       }
> > -
> >       f = qemu_mallocz(sizeof(V9fsFidState));
> Memory leak if we find a cluncked fid here?
> More than that how do you handle this?

clunk request happening parallel to alloc request ? is that 
possible. Only when the alloc succeed the client will find the
fid initialized and only on initialized fid we send clunk request.

> >       f->fid = fid;
> >       f->fid_type = P9_FID_NONE;
> > @@ -300,9 +299,33 @@ free_value:
> >       return retval;
> >   }
> >
> > -static int free_fid(V9fsState *s, int32_t fid)
> > +static int release_fid(V9fsState *s, V9fsFidState *fidp)
> >   {
> >       int retval = 0;
> > +
> > +    if (fidp->fid_type == P9_FID_FILE) {
> > +        retval = v9fs_co_close(s, fidp);
> > +    } else if (fidp->fid_type == P9_FID_DIR) {
> > +        retval = v9fs_co_closedir(s, fidp);
> > +    } else if (fidp->fid_type == P9_FID_XATTR) {
> > +        retval = v9fs_xattr_fid_clunk(s, fidp);
> > +    }
> > +    v9fs_string_free(&fidp->path);
> > +    qemu_free(fidp);
> > +    return retval;
> > +}
> > +
> > +static void put_fid(V9fsState *s, V9fsFidState *fidp)
> > +{
> > +    BUG_ON(!fidp->ref);
> > +    fidp->ref--;
> > +    if (!fidp->ref&&  fidp->clunked) {
> > +        release_fid(s, fidp);
> > +    }
> > +}
> > +
> > +static int free_fid(V9fsState *s, int32_t fid)
> With the changed semantics; I would suggest you to swap the names of
> release_fid() and free_fid()
> 
> Or even better
> free_fid() -> clunk_fid()
> release_fid() -> free_fid()

ok 

-aneesh