This is the first of several patch series to rework the ERTM state
machine.
PATCHv1: Four patches, two patches updating header files were merged
PATCHv2: Reworked utility functions for seq_lists and control headers
PATCHv3: Removed extra debug output, added error handling for
allocation failure, used some long lines at Marcel's request, removed
an unnecessary variable, and added a __set_control function.
Mat Martineau (2):
Bluetooth: Add the l2cap_seq_list structure for tracking frames
(Acked-by Marcel last time, but added new error handling code)
Bluetooth: Functions for handling ERTM control fields
include/net/bluetooth/l2cap.h | 12 ++
net/bluetooth/l2cap_core.c | 251 +++++++++++++++++++++++++++++++++++++++--
2 files changed, 255 insertions(+), 8 deletions(-)
--
1.7.9.4
--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
Hi Szymon -
On Wed, 4 Apr 2012, Szymon Janc wrote:
> Hi Mat,
>
>> A sequence list is a data structure used to track frames that need to
>> be retransmitted, and frames that have been requested for
>> retransmission by the remote device. It can compactly represent a
>> list of sequence numbers within the ERTM transmit window. Memory for
>> the list is allocated once at connection time, and common operations
>> in ERTM are O(1).
>>
>> Signed-off-by: Mat Martineau <[email protected]>
>> ---
>> include/net/bluetooth/l2cap.h | 12 ++++
>> net/bluetooth/l2cap_core.c | 152 ++++++++++++++++++++++++++++++++++++++---
>> 2 files changed, 156 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
>> index f6f0500..5d65b3d 100644
>> --- a/include/net/bluetooth/l2cap.h
>> +++ b/include/net/bluetooth/l2cap.h
>> @@ -407,6 +407,16 @@ struct l2cap_conn_param_update_rsp {
>> #define L2CAP_CONN_PARAM_REJECTED 0x0001
>>
>> /* ----- L2CAP channels and connections ----- */
>> +struct l2cap_seq_list {
>> + __u16 head;
>> + __u16 tail;
>> + __u16 mask;
>> + __u16 *list;
>> +};
>> +
>> +#define L2CAP_SEQ_LIST_CLEAR 0xFFFF
>> +#define L2CAP_SEQ_LIST_TAIL 0x8000
>> +
>> struct srej_list {
>> __u16 tx_seq;
>> struct list_head list;
>> @@ -501,6 +511,8 @@ struct l2cap_chan {
>> struct sk_buff *tx_send_head;
>> struct sk_buff_head tx_q;
>> struct sk_buff_head srej_q;
>> + struct l2cap_seq_list srej_list;
>> + struct l2cap_seq_list retrans_list;
>> struct list_head srej_l;
>>
>> struct list_head list;
>> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
>> index 3caff27..650e9f5 100644
>> --- a/net/bluetooth/l2cap_core.c
>> +++ b/net/bluetooth/l2cap_core.c
>> @@ -233,6 +233,125 @@ static inline void l2cap_chan_set_err(struct l2cap_chan *chan, int err)
>> release_sock(sk);
>> }
>>
>> +/* ---- L2CAP sequence number lists ---- */
>> +
>> +/* For ERTM, ordered lists of sequence numbers must be tracked for
>> + * SREJ requests that are received and for frames that are to be
>> + * retransmitted. These seq_list functions implement a singly-linked
>> + * list in an array, where membership in the list can also be checked
>> + * in constant time. Items can also be added to the tail of the list
>> + * and removed from the head in constant time, without further memory
>> + * allocs or frees.
>> + */
>> +
>> +static int l2cap_seq_list_init(struct l2cap_seq_list *seq_list, u16 size)
>> +{
>> + u16 alloc_size = 1;
>> + int i;
>> +
>> + /* Allocated size is a power of 2 to map sequence numbers
>> + * (which may be up to 14 bits) in to a smaller array that is
>> + * sized for the negotiated ERTM transmit windows.
>> + */
>> + while (alloc_size && alloc_size <= size)
>> + alloc_size <<= 1;
>> + if (!alloc_size)
>> + return -ENOMEM;
>> +
>
> Is it intended that if size is already equal to power of two you still double it?
> And maybe use roundup_pow_of_two macro here?
I didn't know about roundup_pow_of_two, that would be good to use --
and it would address the potential overallocation you noticed.
>> + seq_list->list = kzalloc(sizeof(u16) * alloc_size, GFP_KERNEL);
>> + if (!seq_list->list)
>> + return -ENOMEM;
>> +
>> + seq_list->mask = alloc_size - 1;
>> + seq_list->head = L2CAP_SEQ_LIST_CLEAR;
>> + seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
>> + for (i = 0; i < alloc_size; i++)
>> + seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
>
> Could use memset for this instead of loop, and maybe use kcalloc instead of
> kzalloc to allocate array?
L2CAP_SEQ_LIST_CLEAR is 0xffff, not 0, so it seems best to change the
kzalloc to kmalloc.
It is a coincidence that L2CAP_SEQ_LIST_CLEAR has identical upper and
lower bytes so memset would work, but I think it's better to keep the
existing code for readability. This function is not called often, and
not in performance-critical places.
>> +
>> + return 0;
>> +}
>> +
>> +static inline void l2cap_seq_list_free(struct l2cap_seq_list *seq_list)
>> +{
>> + kfree(seq_list->list);
>> +}
>> +
>> +static inline bool l2cap_seq_list_contains(struct l2cap_seq_list *seq_list,
>> + u16 seq)
>> +{
>> + /* Constant-time check for list membership */
>> + return seq_list->list[seq & seq_list->mask] != L2CAP_SEQ_LIST_CLEAR;
>> +}
>> +
>> +static u16 l2cap_seq_list_remove(struct l2cap_seq_list *seq_list, u16 seq)
>> +{
>> + u16 mask = seq_list->mask;
>> +
>> + if (seq_list->head == L2CAP_SEQ_LIST_CLEAR) {
>> + /* In case someone tries to pop the head of an empty list */
>> + return L2CAP_SEQ_LIST_CLEAR;
>> + } else if (seq_list->head == seq) {
>> + /* Head can be removed in constant time */
>> + seq_list->head = seq_list->list[seq & mask];
>> + seq_list->list[seq & mask] = L2CAP_SEQ_LIST_CLEAR;
>> +
>> + if (seq_list->head == L2CAP_SEQ_LIST_TAIL) {
>> + seq_list->head = L2CAP_SEQ_LIST_CLEAR;
>> + seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
>> + }
>> + } else {
>> + /* Walk the list to find the sequence number */
>> + u16 prev = seq_list->head;
>> + while (seq_list->list[prev & mask] != seq) {
>> + prev = seq_list->list[prev & mask];
>> + if (prev == L2CAP_SEQ_LIST_TAIL)
>> + return L2CAP_SEQ_LIST_CLEAR;
>> + }
>> +
>> + /* Unlink the number from the list and clear it */
>> + seq_list->list[prev & mask] = seq_list->list[seq & mask];
>> + seq_list->list[seq & mask] = L2CAP_SEQ_LIST_CLEAR;
>> + if (seq_list->tail == seq)
>> + seq_list->tail = prev;
>> + }
>> + return seq;
>> +}
>> +
>> +static u16 l2cap_seq_list_pop(struct l2cap_seq_list *seq_list)
>> +{
>> + /* Remove the head in constant time */
>> + return l2cap_seq_list_remove(seq_list, seq_list->head);
>> +}
>> +
>> +static void l2cap_seq_list_clear(struct l2cap_seq_list *seq_list)
>> +{
>> + if (seq_list->head != L2CAP_SEQ_LIST_CLEAR) {
>> + u16 i;
>> + for (i = 0; i <= seq_list->mask; i++)
>> + seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
>
> maybe use memset?
(see above)
Thanks for your comments,
--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
Hi,
> Hi Szymon,
>
> On Wed, Apr 04, 2012 at 10:44:19AM +0200, Szymon Janc wrote:
> > > + seq_list->list = kzalloc(sizeof(u16) * alloc_size, GFP_KERNEL);
> > > + if (!seq_list->list)
> > > + return -ENOMEM;
> > > +
> > > + seq_list->mask = alloc_size - 1;
> > > + seq_list->head = L2CAP_SEQ_LIST_CLEAR;
> > > + seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
> > > + for (i = 0; i < alloc_size; i++)
> > > + seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
> >
> > Could use memset for this instead of loop, and maybe use kcalloc instead of
> > kzalloc to allocate array?
>
> memset is implemented trough the loop anyway and would take 2x more
> iterations.
>
> void *memset(void *s, int c, size_t count)
> {
> char *xs = s;
> while (count--)
> *xs++ = c;
> return s;
> }
This is generic implementation, isn't it? There are some arch specific
implementation in arch/ as well and those should be a bit more efficient
comparing to loop...
--
Szymon Janc
Hi Szymon,
On Wed, Apr 04, 2012 at 10:44:19AM +0200, Szymon Janc wrote:
> > + seq_list->list = kzalloc(sizeof(u16) * alloc_size, GFP_KERNEL);
> > + if (!seq_list->list)
> > + return -ENOMEM;
> > +
> > + seq_list->mask = alloc_size - 1;
> > + seq_list->head = L2CAP_SEQ_LIST_CLEAR;
> > + seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
> > + for (i = 0; i < alloc_size; i++)
> > + seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
>
> Could use memset for this instead of loop, and maybe use kcalloc instead of
> kzalloc to allocate array?
memset is implemented trough the loop anyway and would take 2x more
iterations.
void *memset(void *s, int c, size_t count)
{
char *xs = s;
while (count--)
*xs++ = c;
return s;
}
Best regards
Andrei Emeltchenko
Hi Mat,
> A sequence list is a data structure used to track frames that need to
> be retransmitted, and frames that have been requested for
> retransmission by the remote device. It can compactly represent a
> list of sequence numbers within the ERTM transmit window. Memory for
> the list is allocated once at connection time, and common operations
> in ERTM are O(1).
>
> Signed-off-by: Mat Martineau <[email protected]>
> ---
> include/net/bluetooth/l2cap.h | 12 ++++
> net/bluetooth/l2cap_core.c | 152 ++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 156 insertions(+), 8 deletions(-)
>
> diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
> index f6f0500..5d65b3d 100644
> --- a/include/net/bluetooth/l2cap.h
> +++ b/include/net/bluetooth/l2cap.h
> @@ -407,6 +407,16 @@ struct l2cap_conn_param_update_rsp {
> #define L2CAP_CONN_PARAM_REJECTED 0x0001
>
> /* ----- L2CAP channels and connections ----- */
> +struct l2cap_seq_list {
> + __u16 head;
> + __u16 tail;
> + __u16 mask;
> + __u16 *list;
> +};
> +
> +#define L2CAP_SEQ_LIST_CLEAR 0xFFFF
> +#define L2CAP_SEQ_LIST_TAIL 0x8000
> +
> struct srej_list {
> __u16 tx_seq;
> struct list_head list;
> @@ -501,6 +511,8 @@ struct l2cap_chan {
> struct sk_buff *tx_send_head;
> struct sk_buff_head tx_q;
> struct sk_buff_head srej_q;
> + struct l2cap_seq_list srej_list;
> + struct l2cap_seq_list retrans_list;
> struct list_head srej_l;
>
> struct list_head list;
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 3caff27..650e9f5 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -233,6 +233,125 @@ static inline void l2cap_chan_set_err(struct l2cap_chan *chan, int err)
> release_sock(sk);
> }
>
> +/* ---- L2CAP sequence number lists ---- */
> +
> +/* For ERTM, ordered lists of sequence numbers must be tracked for
> + * SREJ requests that are received and for frames that are to be
> + * retransmitted. These seq_list functions implement a singly-linked
> + * list in an array, where membership in the list can also be checked
> + * in constant time. Items can also be added to the tail of the list
> + * and removed from the head in constant time, without further memory
> + * allocs or frees.
> + */
> +
> +static int l2cap_seq_list_init(struct l2cap_seq_list *seq_list, u16 size)
> +{
> + u16 alloc_size = 1;
> + int i;
> +
> + /* Allocated size is a power of 2 to map sequence numbers
> + * (which may be up to 14 bits) in to a smaller array that is
> + * sized for the negotiated ERTM transmit windows.
> + */
> + while (alloc_size && alloc_size <= size)
> + alloc_size <<= 1;
> + if (!alloc_size)
> + return -ENOMEM;
> +
Is it intended that if size is already equal to power of two you still double it?
And maybe use roundup_pow_of_two macro here?
> + seq_list->list = kzalloc(sizeof(u16) * alloc_size, GFP_KERNEL);
> + if (!seq_list->list)
> + return -ENOMEM;
> +
> + seq_list->mask = alloc_size - 1;
> + seq_list->head = L2CAP_SEQ_LIST_CLEAR;
> + seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
> + for (i = 0; i < alloc_size; i++)
> + seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
Could use memset for this instead of loop, and maybe use kcalloc instead of
kzalloc to allocate array?
> +
> + return 0;
> +}
> +
> +static inline void l2cap_seq_list_free(struct l2cap_seq_list *seq_list)
> +{
> + kfree(seq_list->list);
> +}
> +
> +static inline bool l2cap_seq_list_contains(struct l2cap_seq_list *seq_list,
> + u16 seq)
> +{
> + /* Constant-time check for list membership */
> + return seq_list->list[seq & seq_list->mask] != L2CAP_SEQ_LIST_CLEAR;
> +}
> +
> +static u16 l2cap_seq_list_remove(struct l2cap_seq_list *seq_list, u16 seq)
> +{
> + u16 mask = seq_list->mask;
> +
> + if (seq_list->head == L2CAP_SEQ_LIST_CLEAR) {
> + /* In case someone tries to pop the head of an empty list */
> + return L2CAP_SEQ_LIST_CLEAR;
> + } else if (seq_list->head == seq) {
> + /* Head can be removed in constant time */
> + seq_list->head = seq_list->list[seq & mask];
> + seq_list->list[seq & mask] = L2CAP_SEQ_LIST_CLEAR;
> +
> + if (seq_list->head == L2CAP_SEQ_LIST_TAIL) {
> + seq_list->head = L2CAP_SEQ_LIST_CLEAR;
> + seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
> + }
> + } else {
> + /* Walk the list to find the sequence number */
> + u16 prev = seq_list->head;
> + while (seq_list->list[prev & mask] != seq) {
> + prev = seq_list->list[prev & mask];
> + if (prev == L2CAP_SEQ_LIST_TAIL)
> + return L2CAP_SEQ_LIST_CLEAR;
> + }
> +
> + /* Unlink the number from the list and clear it */
> + seq_list->list[prev & mask] = seq_list->list[seq & mask];
> + seq_list->list[seq & mask] = L2CAP_SEQ_LIST_CLEAR;
> + if (seq_list->tail == seq)
> + seq_list->tail = prev;
> + }
> + return seq;
> +}
> +
> +static u16 l2cap_seq_list_pop(struct l2cap_seq_list *seq_list)
> +{
> + /* Remove the head in constant time */
> + return l2cap_seq_list_remove(seq_list, seq_list->head);
> +}
> +
> +static void l2cap_seq_list_clear(struct l2cap_seq_list *seq_list)
> +{
> + if (seq_list->head != L2CAP_SEQ_LIST_CLEAR) {
> + u16 i;
> + for (i = 0; i <= seq_list->mask; i++)
> + seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
maybe use memset?
--
BR
Szymon Janc
Hi Mat,
On Tue, Apr 03, 2012 at 03:48:52PM -0700, Mat Martineau wrote:
> These functions encode or decode ERTM control fields (extended or
> enhanced) to or from the new l2cap_ctrl structure.
>
> Signed-off-by: Mat Martineau <[email protected]>
Looks good now.
Acked-by: Andrei Emeltchenko <[email protected]>
> ---
> net/bluetooth/l2cap_core.c | 99 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 99 insertions(+)
>
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 650e9f5..b1eac5a 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -780,6 +780,103 @@ static inline void l2cap_send_rr_or_rnr(struct l2cap_chan *chan, u32 control)
> l2cap_send_sframe(chan, control);
> }
>
> +static u16 __pack_enhanced_control(struct l2cap_ctrl *control)
> +{
> + u16 packed;
> +
> + packed = control->reqseq << L2CAP_CTRL_REQSEQ_SHIFT;
> + packed |= control->final << L2CAP_CTRL_FINAL_SHIFT;
> +
> + if (control->sframe) {
> + packed |= control->poll << L2CAP_CTRL_POLL_SHIFT;
> + packed |= control->super << L2CAP_CTRL_SUPER_SHIFT;
> + packed |= L2CAP_CTRL_FRAME_TYPE;
> + } else {
> + packed |= control->sar << L2CAP_CTRL_SAR_SHIFT;
> + packed |= control->txseq << L2CAP_CTRL_TXSEQ_SHIFT;
> + }
> +
> + return packed;
> +}
> +
> +static void __get_enhanced_control(u16 enh, struct l2cap_ctrl *control)
> +{
> + control->reqseq = (enh & L2CAP_CTRL_REQSEQ) >> L2CAP_CTRL_REQSEQ_SHIFT;
> + control->final = (enh & L2CAP_CTRL_FINAL) >> L2CAP_CTRL_FINAL_SHIFT;
> +
> + if (enh & L2CAP_CTRL_FRAME_TYPE) {
> + /* S-Frame */
> + control->sframe = 1;
> + control->poll = (enh & L2CAP_CTRL_POLL) >> L2CAP_CTRL_POLL_SHIFT;
> + control->super = (enh & L2CAP_CTRL_SUPERVISE) >> L2CAP_CTRL_SUPER_SHIFT;
> +
> + control->sar = 0;
> + control->txseq = 0;
> + } else {
> + /* I-Frame */
> + control->sframe = 0;
> + control->sar = (enh & L2CAP_CTRL_SAR) >> L2CAP_CTRL_SAR_SHIFT;
> + control->txseq = (enh & L2CAP_CTRL_TXSEQ) >> L2CAP_CTRL_TXSEQ_SHIFT;
> +
> + control->poll = 0;
> + control->super = 0;
> + }
> +}
> +
> +static u32 __pack_extended_control(struct l2cap_ctrl *control)
> +{
> + u32 packed;
> +
> + packed = control->reqseq << L2CAP_EXT_CTRL_REQSEQ_SHIFT;
> + packed |= control->final << L2CAP_EXT_CTRL_FINAL_SHIFT;
> +
> + if (control->sframe) {
> + packed |= control->poll << L2CAP_EXT_CTRL_POLL_SHIFT;
> + packed |= control->super << L2CAP_EXT_CTRL_SUPER_SHIFT;
> + packed |= L2CAP_EXT_CTRL_FRAME_TYPE;
> + } else {
> + packed |= control->sar << L2CAP_EXT_CTRL_SAR_SHIFT;
> + packed |= control->txseq << L2CAP_EXT_CTRL_TXSEQ_SHIFT;
> + }
> +
> + return packed;
> +}
> +
> +static void __get_extended_control(u32 ext, struct l2cap_ctrl *control)
> +{
> + control->reqseq = (ext & L2CAP_EXT_CTRL_REQSEQ) >> L2CAP_EXT_CTRL_REQSEQ_SHIFT;
> + control->final = (ext & L2CAP_EXT_CTRL_FINAL) >> L2CAP_EXT_CTRL_FINAL_SHIFT;
> +
> + if (ext & L2CAP_EXT_CTRL_FRAME_TYPE) {
> + /* S-Frame */
> + control->sframe = 1;
> + control->poll = (ext & L2CAP_EXT_CTRL_POLL) >> L2CAP_EXT_CTRL_POLL_SHIFT;
> + control->super = (ext & L2CAP_EXT_CTRL_SUPERVISE) >> L2CAP_EXT_CTRL_SUPER_SHIFT;
> +
> + control->sar = 0;
> + control->txseq = 0;
> + } else {
> + /* I-Frame */
> + control->sframe = 0;
> + control->sar = (ext & L2CAP_EXT_CTRL_SAR) >> L2CAP_EXT_CTRL_SAR_SHIFT;
> + control->txseq = (ext & L2CAP_EXT_CTRL_TXSEQ) >> L2CAP_EXT_CTRL_TXSEQ_SHIFT;
> +
> + control->poll = 0;
> + control->super = 0;
> + }
> +}
> +
> +static void __set_control(struct l2cap_chan *chan, struct sk_buff *skb)
> +{
> + if (test_bit(FLAG_EXT_CTRL, &chan->flags)) {
> + __get_extended_control(get_unaligned_le32(skb->data),
> + &bt_cb(skb)->control);
> + } else {
> + __get_enhanced_control(get_unaligned_le16(skb->data),
> + &bt_cb(skb)->control);
> + }
> +}
> +
> static inline int __l2cap_no_conn_pending(struct l2cap_chan *chan)
> {
> return !test_bit(CONF_CONNECT_PEND, &chan->conf_state);
> @@ -4354,6 +4451,8 @@ static int l2cap_ertm_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
> u16 req_seq;
> int len, next_tx_seq_offset, req_seq_offset;
>
> + __set_control(chan, skb);
> +
> control = __get_control(chan, skb->data);
> skb_pull(skb, __ctrl_size(chan));
> len = skb->len;
> --
> 1.7.9.4
>
> --
> Mat Martineau
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
> --
> To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
These functions encode or decode ERTM control fields (extended or
enhanced) to or from the new l2cap_ctrl structure.
Signed-off-by: Mat Martineau <[email protected]>
---
net/bluetooth/l2cap_core.c | 99 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 99 insertions(+)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 650e9f5..b1eac5a 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -780,6 +780,103 @@ static inline void l2cap_send_rr_or_rnr(struct l2cap_chan *chan, u32 control)
l2cap_send_sframe(chan, control);
}
+static u16 __pack_enhanced_control(struct l2cap_ctrl *control)
+{
+ u16 packed;
+
+ packed = control->reqseq << L2CAP_CTRL_REQSEQ_SHIFT;
+ packed |= control->final << L2CAP_CTRL_FINAL_SHIFT;
+
+ if (control->sframe) {
+ packed |= control->poll << L2CAP_CTRL_POLL_SHIFT;
+ packed |= control->super << L2CAP_CTRL_SUPER_SHIFT;
+ packed |= L2CAP_CTRL_FRAME_TYPE;
+ } else {
+ packed |= control->sar << L2CAP_CTRL_SAR_SHIFT;
+ packed |= control->txseq << L2CAP_CTRL_TXSEQ_SHIFT;
+ }
+
+ return packed;
+}
+
+static void __get_enhanced_control(u16 enh, struct l2cap_ctrl *control)
+{
+ control->reqseq = (enh & L2CAP_CTRL_REQSEQ) >> L2CAP_CTRL_REQSEQ_SHIFT;
+ control->final = (enh & L2CAP_CTRL_FINAL) >> L2CAP_CTRL_FINAL_SHIFT;
+
+ if (enh & L2CAP_CTRL_FRAME_TYPE) {
+ /* S-Frame */
+ control->sframe = 1;
+ control->poll = (enh & L2CAP_CTRL_POLL) >> L2CAP_CTRL_POLL_SHIFT;
+ control->super = (enh & L2CAP_CTRL_SUPERVISE) >> L2CAP_CTRL_SUPER_SHIFT;
+
+ control->sar = 0;
+ control->txseq = 0;
+ } else {
+ /* I-Frame */
+ control->sframe = 0;
+ control->sar = (enh & L2CAP_CTRL_SAR) >> L2CAP_CTRL_SAR_SHIFT;
+ control->txseq = (enh & L2CAP_CTRL_TXSEQ) >> L2CAP_CTRL_TXSEQ_SHIFT;
+
+ control->poll = 0;
+ control->super = 0;
+ }
+}
+
+static u32 __pack_extended_control(struct l2cap_ctrl *control)
+{
+ u32 packed;
+
+ packed = control->reqseq << L2CAP_EXT_CTRL_REQSEQ_SHIFT;
+ packed |= control->final << L2CAP_EXT_CTRL_FINAL_SHIFT;
+
+ if (control->sframe) {
+ packed |= control->poll << L2CAP_EXT_CTRL_POLL_SHIFT;
+ packed |= control->super << L2CAP_EXT_CTRL_SUPER_SHIFT;
+ packed |= L2CAP_EXT_CTRL_FRAME_TYPE;
+ } else {
+ packed |= control->sar << L2CAP_EXT_CTRL_SAR_SHIFT;
+ packed |= control->txseq << L2CAP_EXT_CTRL_TXSEQ_SHIFT;
+ }
+
+ return packed;
+}
+
+static void __get_extended_control(u32 ext, struct l2cap_ctrl *control)
+{
+ control->reqseq = (ext & L2CAP_EXT_CTRL_REQSEQ) >> L2CAP_EXT_CTRL_REQSEQ_SHIFT;
+ control->final = (ext & L2CAP_EXT_CTRL_FINAL) >> L2CAP_EXT_CTRL_FINAL_SHIFT;
+
+ if (ext & L2CAP_EXT_CTRL_FRAME_TYPE) {
+ /* S-Frame */
+ control->sframe = 1;
+ control->poll = (ext & L2CAP_EXT_CTRL_POLL) >> L2CAP_EXT_CTRL_POLL_SHIFT;
+ control->super = (ext & L2CAP_EXT_CTRL_SUPERVISE) >> L2CAP_EXT_CTRL_SUPER_SHIFT;
+
+ control->sar = 0;
+ control->txseq = 0;
+ } else {
+ /* I-Frame */
+ control->sframe = 0;
+ control->sar = (ext & L2CAP_EXT_CTRL_SAR) >> L2CAP_EXT_CTRL_SAR_SHIFT;
+ control->txseq = (ext & L2CAP_EXT_CTRL_TXSEQ) >> L2CAP_EXT_CTRL_TXSEQ_SHIFT;
+
+ control->poll = 0;
+ control->super = 0;
+ }
+}
+
+static void __set_control(struct l2cap_chan *chan, struct sk_buff *skb)
+{
+ if (test_bit(FLAG_EXT_CTRL, &chan->flags)) {
+ __get_extended_control(get_unaligned_le32(skb->data),
+ &bt_cb(skb)->control);
+ } else {
+ __get_enhanced_control(get_unaligned_le16(skb->data),
+ &bt_cb(skb)->control);
+ }
+}
+
static inline int __l2cap_no_conn_pending(struct l2cap_chan *chan)
{
return !test_bit(CONF_CONNECT_PEND, &chan->conf_state);
@@ -4354,6 +4451,8 @@ static int l2cap_ertm_data_rcv(struct l2cap_chan *chan, struct sk_buff *skb)
u16 req_seq;
int len, next_tx_seq_offset, req_seq_offset;
+ __set_control(chan, skb);
+
control = __get_control(chan, skb->data);
skb_pull(skb, __ctrl_size(chan));
len = skb->len;
--
1.7.9.4
--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
A sequence list is a data structure used to track frames that need to
be retransmitted, and frames that have been requested for
retransmission by the remote device. It can compactly represent a
list of sequence numbers within the ERTM transmit window. Memory for
the list is allocated once at connection time, and common operations
in ERTM are O(1).
Signed-off-by: Mat Martineau <[email protected]>
---
include/net/bluetooth/l2cap.h | 12 ++++
net/bluetooth/l2cap_core.c | 152 ++++++++++++++++++++++++++++++++++++++---
2 files changed, 156 insertions(+), 8 deletions(-)
diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index f6f0500..5d65b3d 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -407,6 +407,16 @@ struct l2cap_conn_param_update_rsp {
#define L2CAP_CONN_PARAM_REJECTED 0x0001
/* ----- L2CAP channels and connections ----- */
+struct l2cap_seq_list {
+ __u16 head;
+ __u16 tail;
+ __u16 mask;
+ __u16 *list;
+};
+
+#define L2CAP_SEQ_LIST_CLEAR 0xFFFF
+#define L2CAP_SEQ_LIST_TAIL 0x8000
+
struct srej_list {
__u16 tx_seq;
struct list_head list;
@@ -501,6 +511,8 @@ struct l2cap_chan {
struct sk_buff *tx_send_head;
struct sk_buff_head tx_q;
struct sk_buff_head srej_q;
+ struct l2cap_seq_list srej_list;
+ struct l2cap_seq_list retrans_list;
struct list_head srej_l;
struct list_head list;
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 3caff27..650e9f5 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -233,6 +233,125 @@ static inline void l2cap_chan_set_err(struct l2cap_chan *chan, int err)
release_sock(sk);
}
+/* ---- L2CAP sequence number lists ---- */
+
+/* For ERTM, ordered lists of sequence numbers must be tracked for
+ * SREJ requests that are received and for frames that are to be
+ * retransmitted. These seq_list functions implement a singly-linked
+ * list in an array, where membership in the list can also be checked
+ * in constant time. Items can also be added to the tail of the list
+ * and removed from the head in constant time, without further memory
+ * allocs or frees.
+ */
+
+static int l2cap_seq_list_init(struct l2cap_seq_list *seq_list, u16 size)
+{
+ u16 alloc_size = 1;
+ int i;
+
+ /* Allocated size is a power of 2 to map sequence numbers
+ * (which may be up to 14 bits) in to a smaller array that is
+ * sized for the negotiated ERTM transmit windows.
+ */
+ while (alloc_size && alloc_size <= size)
+ alloc_size <<= 1;
+ if (!alloc_size)
+ return -ENOMEM;
+
+ seq_list->list = kzalloc(sizeof(u16) * alloc_size, GFP_KERNEL);
+ if (!seq_list->list)
+ return -ENOMEM;
+
+ seq_list->mask = alloc_size - 1;
+ seq_list->head = L2CAP_SEQ_LIST_CLEAR;
+ seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
+ for (i = 0; i < alloc_size; i++)
+ seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
+
+ return 0;
+}
+
+static inline void l2cap_seq_list_free(struct l2cap_seq_list *seq_list)
+{
+ kfree(seq_list->list);
+}
+
+static inline bool l2cap_seq_list_contains(struct l2cap_seq_list *seq_list,
+ u16 seq)
+{
+ /* Constant-time check for list membership */
+ return seq_list->list[seq & seq_list->mask] != L2CAP_SEQ_LIST_CLEAR;
+}
+
+static u16 l2cap_seq_list_remove(struct l2cap_seq_list *seq_list, u16 seq)
+{
+ u16 mask = seq_list->mask;
+
+ if (seq_list->head == L2CAP_SEQ_LIST_CLEAR) {
+ /* In case someone tries to pop the head of an empty list */
+ return L2CAP_SEQ_LIST_CLEAR;
+ } else if (seq_list->head == seq) {
+ /* Head can be removed in constant time */
+ seq_list->head = seq_list->list[seq & mask];
+ seq_list->list[seq & mask] = L2CAP_SEQ_LIST_CLEAR;
+
+ if (seq_list->head == L2CAP_SEQ_LIST_TAIL) {
+ seq_list->head = L2CAP_SEQ_LIST_CLEAR;
+ seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
+ }
+ } else {
+ /* Walk the list to find the sequence number */
+ u16 prev = seq_list->head;
+ while (seq_list->list[prev & mask] != seq) {
+ prev = seq_list->list[prev & mask];
+ if (prev == L2CAP_SEQ_LIST_TAIL)
+ return L2CAP_SEQ_LIST_CLEAR;
+ }
+
+ /* Unlink the number from the list and clear it */
+ seq_list->list[prev & mask] = seq_list->list[seq & mask];
+ seq_list->list[seq & mask] = L2CAP_SEQ_LIST_CLEAR;
+ if (seq_list->tail == seq)
+ seq_list->tail = prev;
+ }
+ return seq;
+}
+
+static u16 l2cap_seq_list_pop(struct l2cap_seq_list *seq_list)
+{
+ /* Remove the head in constant time */
+ return l2cap_seq_list_remove(seq_list, seq_list->head);
+}
+
+static void l2cap_seq_list_clear(struct l2cap_seq_list *seq_list)
+{
+ if (seq_list->head != L2CAP_SEQ_LIST_CLEAR) {
+ u16 i;
+ for (i = 0; i <= seq_list->mask; i++)
+ seq_list->list[i] = L2CAP_SEQ_LIST_CLEAR;
+
+ seq_list->head = L2CAP_SEQ_LIST_CLEAR;
+ seq_list->tail = L2CAP_SEQ_LIST_CLEAR;
+ }
+}
+
+static void l2cap_seq_list_append(struct l2cap_seq_list *seq_list, u16 seq)
+{
+ u16 mask = seq_list->mask;
+
+ /* All appends happen in constant time */
+
+ if (seq_list->list[seq & mask] == L2CAP_SEQ_LIST_CLEAR) {
+ if (seq_list->tail == L2CAP_SEQ_LIST_CLEAR)
+ seq_list->head = seq;
+ else
+ seq_list->list[seq_list->tail & mask] = seq;
+
+ seq_list->tail = seq;
+ seq_list->list[seq & mask] = L2CAP_SEQ_LIST_TAIL;
+ }
+}
+
static void l2cap_chan_timeout(struct work_struct *work)
{
struct l2cap_chan *chan = container_of(work, struct l2cap_chan,
@@ -404,6 +523,8 @@ static void l2cap_chan_del(struct l2cap_chan *chan, int err)
skb_queue_purge(&chan->srej_q);
+ l2cap_seq_list_free(&chan->srej_list);
+ l2cap_seq_list_free(&chan->retrans_list);
list_for_each_entry_safe(l, tmp, &chan->srej_l, list) {
list_del(&l->list);
kfree(l);
@@ -2038,8 +2159,10 @@ static void l2cap_ack_timeout(struct work_struct *work)
l2cap_chan_put(chan);
}
-static inline void l2cap_ertm_init(struct l2cap_chan *chan)
+static inline int l2cap_ertm_init(struct l2cap_chan *chan)
{
+ int err;
+
chan->expected_ack_seq = 0;
chan->unacked_frames = 0;
chan->buffer_seq = 0;
@@ -2053,6 +2176,11 @@ static inline void l2cap_ertm_init(struct l2cap_chan *chan)
skb_queue_head_init(&chan->srej_q);
INIT_LIST_HEAD(&chan->srej_l);
+ err = l2cap_seq_list_init(&chan->srej_list, chan->tx_win);
+ if (err < 0)
+ return err;
+
+ return l2cap_seq_list_init(&chan->retrans_list, chan->remote_tx_win);
}
static inline __u8 l2cap_select_mode(__u8 mode, __u16 remote_feat_mask)
@@ -2846,7 +2974,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
u16 dcid, flags;
u8 rsp[64];
struct l2cap_chan *chan;
- int len;
+ int len, err = 0;
dcid = __le16_to_cpu(req->dcid);
flags = __le16_to_cpu(req->flags);
@@ -2917,9 +3045,13 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
chan->expected_tx_seq = 0;
skb_queue_head_init(&chan->tx_q);
if (chan->mode == L2CAP_MODE_ERTM)
- l2cap_ertm_init(chan);
+ err = l2cap_ertm_init(chan);
+
+ if (err < 0)
+ l2cap_send_disconn_req(chan->conn, chan, -err);
+ else
+ l2cap_chan_ready(chan);
- l2cap_chan_ready(chan);
goto unlock;
}
@@ -2947,7 +3079,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
unlock:
l2cap_chan_unlock(chan);
- return 0;
+ return err;
}
static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd, u8 *data)
@@ -2956,6 +3088,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
u16 scid, flags, result;
struct l2cap_chan *chan;
int len = le16_to_cpu(cmd->len) - sizeof(*rsp);
+ int err = 0;
scid = __le16_to_cpu(rsp->scid);
flags = __le16_to_cpu(rsp->flags);
@@ -3047,14 +3180,17 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
chan->expected_tx_seq = 0;
skb_queue_head_init(&chan->tx_q);
if (chan->mode == L2CAP_MODE_ERTM)
- l2cap_ertm_init(chan);
+ err = l2cap_ertm_init(chan);
- l2cap_chan_ready(chan);
+ if (err < 0)
+ l2cap_send_disconn_req(chan->conn, chan, -err);
+ else
+ l2cap_chan_ready(chan);
}
done:
l2cap_chan_unlock(chan);
- return 0;
+ return err;
}
static inline int l2cap_disconnect_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd, u8 *data)
--
1.7.9.4
--
Mat Martineau
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum