On Mon, 30 Jul 2012, Alex Elder wrote:
> On 07/30/2012 10:59 AM, Sage Weil wrote:
> > This function's calling convention is very limiting. In particular,
> > we can't return any error other than ENOMEM (and only implicitly),
> > which is a problem (see next patch).
> >
> > Instead, return an normal 0 or error code, and make the skip a pointer
> > output parameter. Drop the useless in_hdr argument (we have the con
> > pointer).
> >
> > Signed-off-by: Sage Weil <sage@xxxxxxxxxxx>
>
> I think this is a good change. I have a few minor nits below
> but it looks good.
>
> Reviewed-by: Alex Elder <elder@xxxxxxxxxxx>
>
> > ---
> > net/ceph/messenger.c | 56 ++++++++++++++++++++++++++++----------------------
> > 1 file changed, 31 insertions(+), 25 deletions(-)
> >
> > diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> > index c3b628c..5177af0 100644
> > --- a/net/ceph/messenger.c
> > +++ b/net/ceph/messenger.c
>
> . . .
>
> > @@ -2715,43 +2714,50 @@ static int ceph_alloc_middle(struct ceph_connection *con, struct ceph_msg *msg)
> > * connection, and save the result in con->in_msg. Uses the
> > * connection's private alloc_msg op if available.
> > *
> > - * Returns true if the message should be skipped, false otherwise.
> > - * If true is returned (skip message), con->in_msg will be NULL.
> > - * If false is returned, con->in_msg will contain a pointer to the
> > - * newly-allocated message, or NULL in case of memory exhaustion.
> > + * Returns 0 on success, or a negative error code.
> > + *
> > + * On success, *skip may be set to 1:
> > + * - the next message should be skipped and ignored.
> > + * - con->in_msg == NULL.
>
> I'm pretty sure you mean that con->in_msg will be null if *skip
> is 1, but it isn't crystal clear the way it's written here.
>
> > + * or *skip may be 0:
> > + * - con->in_msg is non-zero.
>
> Use "non-null" since it's a pointer, or "a valid message pointer".
fixed those
>
> > + * On error (ENOMEM, EAGAIN, ...),
> > + * - con->in_msg == NULL
> > */
> > -static bool ceph_con_in_msg_alloc(struct ceph_connection *con,
> > - struct ceph_msg_header *hdr)
> > +static int ceph_con_in_msg_alloc(struct ceph_connection *con, int *skip)
> > {
>
> Getting rid of the hdr argument here was a good idea anyway, since
> only &con->in_hdr is ever used.
>
> > + struct ceph_msg_header *hdr = &con->in_hdr;
> > int type = le16_to_cpu(hdr->type);
> > int front_len = le32_to_cpu(hdr->front_len);
> > int middle_len = le32_to_cpu(hdr->middle_len);
> > - int ret;
> > + int ret = 0;
> >
> > BUG_ON(con->in_msg != NULL);
> >
> > if (con->ops->alloc_msg) {
> > - int skip = 0;
> > -
> > mutex_unlock(&con->mutex);
> > - con->in_msg = con->ops->alloc_msg(con, hdr, &skip);
> > + con->in_msg = con->ops->alloc_msg(con, hdr, skip);
> > mutex_lock(&con->mutex);
> > if (con->in_msg) {
> > con->in_msg->con = con->ops->get(con);
> > BUG_ON(con->in_msg->con == NULL);
> > }
> > - if (skip)
> > + if (*skip) {
> > con->in_msg = NULL;
> > -
> > - if (!con->in_msg)
> > - return skip != 0;
> > + return 0;
> > + }
> > + if (!con->in_msg) {
> > + con->error_msg =
> > + "error allocating memory for incoming message";
> > + return -ENOMEM;
> > + }
> > }
> > if (!con->in_msg) {
> > con->in_msg = ceph_msg_new(type, front_len, GFP_NOFS, false);
> > if (!con->in_msg) {
> > pr_err("unable to allocate msg type %d len %d\n",
> > type, front_len);
> > - return false;
> > + return -ENOMEM;
> > }
> > con->in_msg->con = con->ops->get(con);
> > BUG_ON(con->in_msg->con == NULL);
> > @@ -2767,7 +2773,7 @@ static bool ceph_con_in_msg_alloc(struct ceph_connection *con,
> > }
> > }
> >
> > - return false;
> > + return ret;
>
> I believe ret will always be 0 here, and if you agree, this
> should just be more direct about it:
I can be non-zero from the alloc_middle case above.
thanks
>
> return 0;
>
> > }
> >
> >
> >
>
>
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