Re: [PATCH v2 01/15] NTB: Rename NTB messaging API methods

Jon Mason
2017-12-05T18:07:33Z

On Tue, Dec 5, 2017 at 12:31 PM, Serge Semin <fancer.lancer@gmail.com> wrote:
> On Tue, Dec 05, 2017 at 11:49:10AM -0500, Jon Mason <jdmason@kudzu.us> wrote:
>> On Sun, Dec 3, 2017 at 2:17 PM, Serge Semin <fancer.lancer@gmail.com> wrote:
>> > There is a common methods signature form used over all the NTB API
>> > like functions naming scheme, arguments names and order, etc.
>> > Recently added NTB messaging API IO callbacks were named a bit
>> > different so should be renamed to be in compliance with the rest
>> > of the API. The changes are made in a way so the developers won't
>> > be able to compile their code without being informed by the compiler.
>> >
>> > Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
>> > ---
>> > drivers/ntb/hw/idt/ntb_hw_idt.c | 27 ++++++++++++---------------
>> > include/linux/ntb.h | 34 ++++++++++++++++------------------
>> > 2 files changed, 28 insertions(+), 33 deletions(-)
>> >
>> > diff --git a/drivers/ntb/hw/idt/ntb_hw_idt.c b/drivers/ntb/hw/idt/ntb_hw_idt.c
>> > index 0cd79f367f7c..6fb87c0f0d97 100644
>> > --- a/drivers/ntb/hw/idt/ntb_hw_idt.c
>> > +++ b/drivers/ntb/hw/idt/ntb_hw_idt.c
>> > @@ -1744,20 +1744,19 @@ static int idt_ntb_msg_clear_mask(struct ntb_dev *ntb, u64 mask_bits)
>> > * idt_ntb_msg_read() - read message register with specified index
>> > * (NTB API callback)
>> > * @ntb: NTB device context.
>> > - * @midx: Message register index
>> > * @pidx: OUT - Port index of peer device a message retrieved from
>> > - * @msg: OUT - Data
>> > + * @midx: Message register index
>> > *
>> > * Read data from the specified message register and source register.
>> > *
>> > - * Return: zero on success, negative error if invalid argument passed.
>> > + * Return: inbound message register value.
>> > */
>> > -static int idt_ntb_msg_read(struct ntb_dev *ntb, int midx, int *pidx, u32 *msg)
>> > +static u32 idt_ntb_msg_read(struct ntb_dev *ntb, int *pidx, int midx)
>> > {
>> > struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);
>> >
>> > if (midx < 0 || IDT_MSG_CNT <= midx)
>> > - return -EINVAL;
>> > + return (u32)-1;
>>
>> Please don't do this. If this is an error return standard error
>> number. And why are we casting to an unsigned int now?
>>
>
> We discussed these changes on the v1 series. Additionally I asked similar
> question sometime ago even before the patchset was introduced.
> This patch is made to provide the Message interface similar to the Scratchpad
> one. I didn't introduce anything new or unjustified. As you can see the
> spad_read/peer_spad_read methods return u32 type too. As well as the
> Intel/AMD callbacks. The functions are intentionally made to return FFs
> in case if some of the passed arguments get out from the allowed limits.
> In such circumstances the return value emulates a situation like if user would
> reference an invalid PCIe MMIO address. Since the 32-bits register can in general
> have any value including -errno ones, then returning an error within the NTB API
> would be incorrect. I remember Allen described it this way.
> Nobody argued about it last time. If you think it's incorrect, then it should be
> changed in both Scratchpad and Message register interfaces.

Just because no one said anything before, doesn't mean it's
acceptable. I think that is the official Linux code review mantra ;-)

Okay, if we are going to do it this way, then return ~0 instead. At
least that way there is no ugly cast.

>
>> >
>> > /* Retrieve source port index of the message */
>> > if (pidx != NULL) {
>> > @@ -1772,18 +1771,15 @@ static int idt_ntb_msg_read(struct ntb_dev *ntb, int midx, int *pidx, u32 *msg)
>> > }
>> >
>> > /* Retrieve data of the corresponding message register */
>> > - if (msg != NULL)
>> > - *msg = idt_nt_read(ndev, ntdata_tbl.msgs[midx].in);
>> > -
>> > - return 0;
>> > + return idt_nt_read(ndev, ntdata_tbl.msgs[midx].in);
>> > }
>> >
>> > /*
>> > - * idt_ntb_msg_write() - write data to the specified message register
>> > - * (NTB API callback)
>> > + * idt_ntb_peer_msg_write() - write data to the specified message register
>> > + * (NTB API callback)
>> > * @ntb: NTB device context.
>> > - * @midx: Message register index
>> > * @pidx: Port index of peer device a message being sent to
>> > + * @midx: Message register index
>> > * @msg: Data to send
>> > *
>> > * Just try to send data to a peer. Message status register should be
>> > @@ -1791,7 +1787,8 @@ static int idt_ntb_msg_read(struct ntb_dev *ntb, int midx, int *pidx, u32 *msg)
>> > *
>> > * Return: zero on success, negative error if invalid argument passed.
>> > */
>> > -static int idt_ntb_msg_write(struct ntb_dev *ntb, int midx, int pidx, u32 msg)
>> > +static int idt_ntb_peer_msg_write(struct ntb_dev *ntb, int pidx, int midx,
>> > + u32 msg)
>> > {
>> > struct idt_ntb_dev *ndev = to_ndev_ntb(ntb);
>> > unsigned long irqflags;
>> > @@ -2058,7 +2055,7 @@ static const struct ntb_dev_ops idt_ntb_ops = {
>> > .msg_set_mask = idt_ntb_msg_set_mask,
>> > .msg_clear_mask = idt_ntb_msg_clear_mask,
>> > .msg_read = idt_ntb_msg_read,
>> > - .msg_write = idt_ntb_msg_write
>> > + .peer_msg_write = idt_ntb_peer_msg_write
>> > };
>> >
>> > /*
>> > @@ -2269,7 +2266,7 @@ static ssize_t idt_dbgfs_info_read(struct file *filp, char __user *ubuf,
>> > "Message data:\n");
>> > for (idx = 0; idx < IDT_MSG_CNT; idx++) {
>> > int src;
>> > - (void)idt_ntb_msg_read(&ndev->ntb, idx, &src, &data);
>> > + data = idt_ntb_msg_read(&ndev->ntb, &src, idx);
>> > off += scnprintf(strbuf + off, size - off,
>> > "\t%hhu. 0x%08x from peer %hhu (Port %hhu)\n",
>> > idx, data, src, ndev->peers[src].port);
>> > diff --git a/include/linux/ntb.h b/include/linux/ntb.h
>> > index c308964777eb..c1646f2c6344 100644
>> > --- a/include/linux/ntb.h
>> > +++ b/include/linux/ntb.h
>> > @@ -250,7 +250,7 @@ static inline int ntb_ctx_ops_is_valid(const struct ntb_ctx_ops *ops)
>> > * @msg_set_mask: See ntb_msg_set_mask().
>> > * @msg_clear_mask: See ntb_msg_clear_mask().
>> > * @msg_read: See ntb_msg_read().
>> > - * @msg_write: See ntb_msg_write().
>> > + * @peer_msg_write: See ntb_peer_msg_write().
>> > */
>> > struct ntb_dev_ops {
>> > int (*port_number)(struct ntb_dev *ntb);
>> > @@ -321,8 +321,8 @@ struct ntb_dev_ops {
>> > int (*msg_clear_sts)(struct ntb_dev *ntb, u64 sts_bits);
>> > int (*msg_set_mask)(struct ntb_dev *ntb, u64 mask_bits);
>> > int (*msg_clear_mask)(struct ntb_dev *ntb, u64 mask_bits);
>> > - int (*msg_read)(struct ntb_dev *ntb, int midx, int *pidx, u32 *msg);
>> > - int (*msg_write)(struct ntb_dev *ntb, int midx, int pidx, u32 msg);
>> > + u32 (*msg_read)(struct ntb_dev *ntb, int *pidx, int midx);
>> > + int (*peer_msg_write)(struct ntb_dev *ntb, int pidx, int midx, u32 msg);
>> > };
>> >
>> > static inline int ntb_dev_ops_is_valid(const struct ntb_dev_ops *ops)
>> > @@ -384,7 +384,7 @@ static inline int ntb_dev_ops_is_valid(const struct ntb_dev_ops *ops)
>> > /* !ops->msg_set_mask == !ops->msg_count && */
>> > /* !ops->msg_clear_mask == !ops->msg_count && */
>> > !ops->msg_read == !ops->msg_count &&
>> > - !ops->msg_write == !ops->msg_count &&
>> > + !ops->peer_msg_write == !ops->msg_count &&
>> > 1;
>> > }
>> >
>> > @@ -1459,31 +1459,29 @@ static inline int ntb_msg_clear_mask(struct ntb_dev *ntb, u64 mask_bits)
>> > }
>> >
>> > /**
>> > - * ntb_msg_read() - read message register with specified index
>> > + * ntb_msg_read() - read inbound message register with specified index
>> > * @ntb: NTB device context.
>> > - * @midx: Message register index
>> > * @pidx: OUT - Port index of peer device a message retrieved from
>> > - * @msg: OUT - Data
>> > + * @midx: Message register index
>> > *
>> > * Read data from the specified message register. Source port index of a
>> > * message is retrieved as well.
>> > *
>> > - * Return: Zero on success, otherwise a negative error number.
>> > + * Return: The value of the inbound message register.
>> > */
>> > -static inline int ntb_msg_read(struct ntb_dev *ntb, int midx, int *pidx,
>> > - u32 *msg)
>> > +static inline u32 ntb_msg_read(struct ntb_dev *ntb, int *pidx, int midx)
>> > {
>> > if (!ntb->ops->msg_read)
>> > - return -EINVAL;
>> > + return ~(u32)0;
>>
>> Same here but in a different way. Please revert this.
>>
>
> Please see the comment above.
>
>> >
>> > - return ntb->ops->msg_read(ntb, midx, pidx, msg);
>> > + return ntb->ops->msg_read(ntb, pidx, midx);
>> > }
>> >
>> > /**
>> > - * ntb_msg_write() - write data to the specified message register
>> > + * ntb_peer_msg_write() - write data to the specified peer message register
>> > * @ntb: NTB device context.
>> > - * @midx: Message register index
>> > * @pidx: Port index of peer device a message being sent to
>> > + * @midx: Message register index
>> > * @msg: Data to send
>> > *
>> > * Send data to a specified peer device using the defined message register.
>> > @@ -1492,13 +1490,13 @@ static inline int ntb_msg_read(struct ntb_dev *ntb, int midx, int *pidx,
>> > *
>> > * Return: Zero on success, otherwise a negative error number.
>> > */
>> > -static inline int ntb_msg_write(struct ntb_dev *ntb, int midx, int pidx,
>> > - u32 msg)
>> > +static inline int ntb_peer_msg_write(struct ntb_dev *ntb, int pidx, int midx,
>> > + u32 msg)
>> > {
>> > - if (!ntb->ops->msg_write)
>> > + if (!ntb->ops->peer_msg_write)
>> > return -EINVAL;
>> >
>> > - return ntb->ops->msg_write(ntb, midx, pidx, msg);
>> > + return ntb->ops->peer_msg_write(ntb, pidx, midx, msg);
>> > }
>> >
>> > #endif
>> > --
>> > 2.12.0
>> >
>>
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