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Message-ID: <87r3hw1a3n.fsf@vitty.brq.redhat.com>
Date: Tue, 05 Jan 2016 13:31:24 +0100
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: Dexuan Cui <decui@...rosoft.com>
Cc: gregkh@...uxfoundation.org, davem@...emloft.net,
stephen@...workplumber.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
driverdev-devel@...uxdriverproject.org, olaf@...fle.de,
apw@...onical.com, jasowang@...hat.com, kys@...rosoft.com,
pebolle@...cali.nl, stefanha@...hat.com, dan.carpenter@...cle.com
Subject: Re: [PATCH V5 4/9] Drivers: hv: ring_buffer: enhance hv_ringbuffer_read() to support hvsock
Dexuan Cui <decui@...rosoft.com> writes:
> To get the payload of hvsock, we need raw=0 to skip the level-1 header
> (i.e., struct vmpacket_descriptor desc) and we also need to skip the
> level-2 header (i.e., struct vmpipe_proto_header pipe_hdr).
>
> NB: if the length of the hvsock payload is not aligned with the 8-byte
> boundeary, at most 7 padding bytes are appended, so the real hvsock
> payload's length must be retrieved by the pipe_hdr.data_size field.
>
> I 'upgrade' the 'raw' parameter of hv_ringbuffer_read() to a
> 'read_flags', trying to share the logic of the function.
When I was touching this code last time I was actually thinking about
eliminating 'raw' flag by making all ring reads raw and moving this
header filtering job to the upper layer (as we already have
vmbus_recvpacket()/vmbus_recvpacket_raw()) but for some reason I didn't
do it. I believe you have more or less the same reasoing for introducing
new read type instead of parsing this at a higher level. Some comments
below ...
>
> This patch is required by the next patch, which will introduce the hvsock
> send/recv APIs.
>
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
> drivers/hv/channel.c | 10 +++++----
> drivers/hv/hyperv_vmbus.h | 13 +++++++++++-
> drivers/hv/ring_buffer.c | 54 ++++++++++++++++++++++++++++++++++++-----------
> include/linux/hyperv.h | 12 +++++++++++
> 4 files changed, 72 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
> index eaaa066..cc49966 100644
> --- a/drivers/hv/channel.c
> +++ b/drivers/hv/channel.c
> @@ -940,13 +940,14 @@ EXPORT_SYMBOL_GPL(vmbus_sendpacket_multipagebuffer);
> static inline int
> __vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
> u32 bufferlen, u32 *buffer_actual_len, u64 *requestid,
> - bool raw)
> + u32 read_flags)
> {
> int ret;
> bool signal = false;
>
> ret = hv_ringbuffer_read(&channel->inbound, buffer, bufferlen,
> - buffer_actual_len, requestid, &signal, raw);
> + buffer_actual_len, requestid, &signal,
> + read_flags);
>
> if (signal)
> vmbus_setevent(channel);
> @@ -959,7 +960,7 @@ int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
> u64 *requestid)
> {
> return __vmbus_recvpacket(channel, buffer, bufferlen,
> - buffer_actual_len, requestid, false);
> + buffer_actual_len, requestid, 0);
> }
> EXPORT_SYMBOL(vmbus_recvpacket);
>
> @@ -971,6 +972,7 @@ int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
> u64 *requestid)
> {
> return __vmbus_recvpacket(channel, buffer, bufferlen,
> - buffer_actual_len, requestid, true);
> + buffer_actual_len, requestid,
> + HV_RINGBUFFER_READ_FLAG_RAW);
> }
> EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
> index 0411b7b..46206b6 100644
> --- a/drivers/hv/hyperv_vmbus.h
> +++ b/drivers/hv/hyperv_vmbus.h
> @@ -619,9 +619,20 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *ring_info,
> struct kvec *kv_list,
> u32 kv_count, bool *signal);
>
> +/*
> + * By default, a read_flags of 0 means: the payload offset is
> + * sizeof(struct vmpacket_descriptor).
> + *
> + * If HV_RINGBUFFER_READ_FLAG_RAW is used, the payload offset is 0.
> + *
> + * If HV_RINGBUFFER_READ_FLAG_HVSOCK is used, the payload offset is
> + * sizeof(struct vmpacket_descriptor) + sizeof(struct
> vmpipe_proto_header).
So these are mutually exclusive, right? Should we introduce 'int
payload_offset' parameter instead of flags?
> + */
> +#define HV_RINGBUFFER_READ_FLAG_RAW (1 << 0)
> +#define HV_RINGBUFFER_READ_FLAG_HVSOCK (1 << 1)
> int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
> void *buffer, u32 buflen, u32 *buffer_actual_len,
> - u64 *requestid, bool *signal, bool raw);
> + u64 *requestid, bool *signal, u32 read_flags);
>
> void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
> struct hv_ring_buffer_debug_info *debug_info);
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> index b53702c..03a509c 100644
> --- a/drivers/hv/ring_buffer.c
> +++ b/drivers/hv/ring_buffer.c
> @@ -382,32 +382,43 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
>
> int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
> void *buffer, u32 buflen, u32 *buffer_actual_len,
> - u64 *requestid, bool *signal, bool raw)
> + u64 *requestid, bool *signal, u32 read_flags)
> {
> + bool raw = !!(read_flags & HV_RINGBUFFER_READ_FLAG_RAW);
> + bool hvsock = !!(read_flags & HV_RINGBUFFER_READ_FLAG_HVSOCK);
> +
> u32 bytes_avail_towrite;
> u32 bytes_avail_toread;
> u32 next_read_location = 0;
> u64 prev_indices = 0;
> unsigned long flags;
> - struct vmpacket_descriptor desc;
> + struct vmpipe_proto_header *pipe_hdr;
> + struct vmpacket_descriptor *desc;
> u32 offset;
> - u32 packetlen;
> + u32 packetlen, tot_hdrlen;
> int ret = 0;
>
> if (buflen <= 0)
> return -EINVAL;
>
> + tot_hdrlen = sizeof(*desc);
> + if (hvsock)
> + tot_hdrlen += sizeof(*pipe_hdr);
> +
> spin_lock_irqsave(&inring_info->ring_lock, flags);
>
> *buffer_actual_len = 0;
> - *requestid = 0;
> +
> + /* If some driver doesn't need the info, a NULL is passed in. */
> + if (requestid)
> + *requestid = 0;
>
> hv_get_ringbuffer_availbytes(inring_info,
> &bytes_avail_toread,
> &bytes_avail_towrite);
>
> /* Make sure there is something to read */
> - if (bytes_avail_toread < sizeof(desc)) {
> + if (bytes_avail_toread < tot_hdrlen) {
> /*
> * No error is set when there is even no header, drivers are
> * supposed to analyze buffer_actual_len.
> @@ -415,17 +426,26 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
> goto out_unlock;
> }
>
> + if (tot_hdrlen > buflen) {
> + ret = -ENOBUFS;
> + goto out_unlock;
> + }
> +
> + desc = (struct vmpacket_descriptor *)buffer;
> +
> next_read_location = hv_get_next_read_location(inring_info);
> - next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc,
> - sizeof(desc),
> + next_read_location = hv_copyfrom_ringbuffer(inring_info, desc,
> + tot_hdrlen,
> next_read_location);
> + offset = 0;
> + if (!raw)
> + offset += (desc->offset8 << 3);
> + if (hvsock)
> + offset += sizeof(*pipe_hdr);
So in case of !raw and hvsock we add both offsets?
>
> - offset = raw ? 0 : (desc.offset8 << 3);
> - packetlen = (desc.len8 << 3) - offset;
> - *buffer_actual_len = packetlen;
> - *requestid = desc.trans_id;
> + packetlen = (desc->len8 << 3) - offset;
>
> - if (bytes_avail_toread < packetlen + offset) {
> + if (bytes_avail_toread < (desc->len8 << 3)) {
> ret = -EAGAIN;
> goto out_unlock;
> }
> @@ -435,6 +455,16 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
> goto out_unlock;
> }
>
> + if (requestid)
> + *requestid = desc->trans_id;
> +
> + if (!hvsock)
> + *buffer_actual_len = packetlen;
> + else {
> + pipe_hdr = (struct vmpipe_proto_header *)(desc + 1);
> + *buffer_actual_len = pipe_hdr->data_size;
> + }
> +
> next_read_location =
> hv_get_next_readlocation_withoffset(inring_info, offset);
>
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index b835d80..e005223 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1268,4 +1268,16 @@ extern __u32 vmbus_proto_version;
>
> int vmbus_send_tl_connect_request(const uuid_le *shv_guest_servie_id,
> const uuid_le *shv_host_servie_id);
> +struct vmpipe_proto_header {
> + u32 pkt_type;
> +
> + union {
> + u32 data_size;
> + struct {
> + u16 data_size;
> + u16 offset;
> + } partial;
> + };
> +} __packed;
> +
> #endif /* _HYPERV_H */
--
Vitaly
--
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