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9p: Documentation updates

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The kernel-doc comments of much of the 9p system have been in disarray since
reorganization.  This patch fixes those problems, adds additional documentation
and a template book which collects the 9p information.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
This commit is contained in:
Eric Van Hensbergen
2008-03-05 07:08:09 -06:00
committed by Eric Van Hensbergen
parent b32a09db4f
commit ee443996a3
18 changed files with 852 additions and 122 deletions
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155
net/9p/trans_virtio.c
View File

@@ -55,23 +55,69 @@ static int chan_index;
#define P9_INIT_MAXTAG 16
#define REQ_STATUS_IDLE 0
#define REQ_STATUS_SENT 1
#define REQ_STATUS_RCVD 2
#define REQ_STATUS_FLSH 3
/**
* enum p9_req_status_t - virtio request status
* @REQ_STATUS_IDLE: request slot unused
* @REQ_STATUS_SENT: request sent to server
* @REQ_STATUS_RCVD: response received from server
* @REQ_STATUS_FLSH: request has been flushed
*
* The @REQ_STATUS_IDLE state is used to mark a request slot as unused
* but use is actually tracked by the idpool structure which handles tag
* id allocation.
*
*/
enum p9_req_status_t {
REQ_STATUS_IDLE,
REQ_STATUS_SENT,
REQ_STATUS_RCVD,
REQ_STATUS_FLSH,
};
/**
* struct p9_req_t - virtio request slots
* @status: status of this request slot
* @wq: wait_queue for the client to block on for this request
*
* The virtio transport uses an array to track outstanding requests
* instead of a list. While this may incurr overhead during initial
* allocation or expansion, it makes request lookup much easier as the
* tag id is a index into an array. (We use tag+1 so that we can accomodate
* the -1 tag for the T_VERSION request).
* This also has the nice effect of only having to allocate wait_queues
* once, instead of constantly allocating and freeing them. Its possible
* other resources could benefit from this scheme as well.
*
*/
struct p9_req_t {
int status;
wait_queue_head_t *wq;
};
/* We keep all per-channel information in a structure.
/**
* struct virtio_chan - per-instance transport information
* @initialized: whether the channel is initialized
* @inuse: whether the channel is in use
* @lock: protects multiple elements within this structure
* @vdev: virtio dev associated with this channel
* @vq: virtio queue associated with this channel
* @tagpool: accounting for tag ids (and request slots)
* @reqs: array of request slots
* @max_tag: current number of request_slots allocated
* @sg: scatter gather list which is used to pack a request (protected?)
*
* We keep all per-channel information in a structure.
* This structure is allocated within the devices dev->mem space.
* A pointer to the structure will get put in the transport private.
*
*/
static struct virtio_chan {
bool initialized; /* channel is initialized */
bool inuse; /* channel is in use */
bool initialized;
bool inuse;
spinlock_t lock;
@@ -86,7 +132,19 @@ static struct virtio_chan {
struct scatterlist sg[VIRTQUEUE_NUM];
} channels[MAX_9P_CHAN];
/* Lookup requests by tag */
/**
* p9_lookup_tag - Lookup requests by tag
* @c: virtio channel to lookup tag within
* @tag: numeric id for transaction
*
* this is a simple array lookup, but will grow the
* request_slots as necessary to accomodate transaction
* ids which did not previously have a slot.
*
* Bugs: there is currently no upper limit on request slots set
* here, but that should be constrained by the id accounting.
*/
static struct p9_req_t *p9_lookup_tag(struct virtio_chan *c, u16 tag)
{
/* This looks up the original request by tag so we know which
@@ -130,6 +188,15 @@ static unsigned int rest_of_page(void *data)
return PAGE_SIZE - ((unsigned long)data % PAGE_SIZE);
}
/**
* p9_virtio_close - reclaim resources of a channel
* @trans: transport state
*
* This reclaims a channel by freeing its resources and
* reseting its inuse flag.
*
*/
static void p9_virtio_close(struct p9_trans *trans)
{
struct virtio_chan *chan = trans->priv;
@@ -151,6 +218,19 @@ static void p9_virtio_close(struct p9_trans *trans)
kfree(trans);
}
/**
* req_done - callback which signals activity from the server
* @vq: virtio queue activity was received on
*
* This notifies us that the server has triggered some activity
* on the virtio channel - most likely a response to request we
* sent. Figure out which requests now have responses and wake up
* those threads.
*
* Bugs: could do with some additional sanity checking, but appears to work.
*
*/
static void req_done(struct virtqueue *vq)
{
struct virtio_chan *chan = vq->vdev->priv;
@@ -169,6 +249,20 @@ static void req_done(struct virtqueue *vq)
spin_unlock_irqrestore(&chan->lock, flags);
}
/**
* pack_sg_list - pack a scatter gather list from a linear buffer
* @sg: scatter/gather list to pack into
* @start: which segment of the sg_list to start at
* @limit: maximum segment to pack data to
* @data: data to pack into scatter/gather list
* @count: amount of data to pack into the scatter/gather list
*
* sg_lists have multiple segments of various sizes. This will pack
* arbitrary data into an existing scatter gather list, segmenting the
* data as necessary within constraints.
*
*/
static int
pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
int count)
@@ -189,6 +283,14 @@ pack_sg_list(struct scatterlist *sg, int start, int limit, char *data,
return index-start;
}
/**
* p9_virtio_rpc - issue a request and wait for a response
* @t: transport state
* @tc: &p9_fcall request to transmit
* @rc: &p9_fcall to put reponse into
*
*/
static int
p9_virtio_rpc(struct p9_trans *t, struct p9_fcall *tc, struct p9_fcall **rc)
{
@@ -263,6 +365,16 @@ p9_virtio_rpc(struct p9_trans *t, struct p9_fcall *tc, struct p9_fcall **rc)
return 0;
}
/**
* p9_virtio_probe - probe for existence of 9P virtio channels
* @vdev: virtio device to probe
*
* This probes for existing virtio channels. At present only
* a single channel is in use, so in the future more work may need
* to be done here.
*
*/
static int p9_virtio_probe(struct virtio_device *vdev)
{
int err;
@@ -307,11 +419,28 @@ fail:
return err;
}
/* This sets up a transport channel for 9p communication. Right now
/**
* p9_virtio_create - allocate a new virtio channel
* @devname: string identifying the channel to connect to (unused)
* @args: args passed from sys_mount() for per-transport options (unused)
* @msize: requested maximum packet size
* @extended: 9p2000.u enabled flag
*
* This sets up a transport channel for 9p communication. Right now
* we only match the first available channel, but eventually we couldlook up
* alternate channels by matching devname versus a virtio_config entry.
* We use a simple reference count mechanism to ensure that only a single
* mount has a channel open at a time. */
* mount has a channel open at a time.
*
* Bugs: doesn't allow identification of a specific channel
* to allocate, channels are allocated sequentially. This was
* a pragmatic decision to get things rolling, but ideally some
* way of identifying the channel to attach to would be nice
* if we are going to support multiple channels.
*
*/
static struct p9_trans *
p9_virtio_create(const char *devname, char *args, int msize,
unsigned char extended)
@@ -360,6 +489,12 @@ p9_virtio_create(const char *devname, char *args, int msize,
return trans;
}
/**
* p9_virtio_remove - clean up resources associated with a virtio device
* @vdev: virtio device to remove
*
*/
static void p9_virtio_remove(struct virtio_device *vdev)
{
struct virtio_chan *chan = vdev->priv;