[PATCH] Replace the OOSEQ max bytes and pbufs constants with functions.

Some systems need to take into account an RX buffer pool size when
advising an appropriate number of RX pbufs to queue on the ooseq
list. For some systems there is a practical hard limit beyond which
the rx pool becomes exhausted blocking reception of further buffers
until some are freed.

It also helps to be able to consider the available dynamic memory when
advising an appropriate maximum number of bytes to buffer on the ooseq
list.

These decisions can also benefit from knowing the number already
allocated on a particular pcb, so the ooseq tcp segement is passed to
these functions. For example, if the system only wants to allow the
total number of rx pbufs queued on all the ooseq lists to grow by one
and a pcb already has two then it can return three for this call, but
might return one for another call - supporting a greedy allocation
strategy.

Signed-off-by: goldsimon <goldsimon@gmx.de>

src/core/tcp_in.c

@@ -96,9 +96,9 @@ static int tcp_input_delayed_close(struct tcp_pcb *pcb);
 #if LWIP_TCP_SACK_OUT
 static void tcp_add_sack(struct tcp_pcb *pcb, u32_t left, u32_t right);
 static void tcp_remove_sacks_lt(struct tcp_pcb *pcb, u32_t seq);
-#if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS
+#if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
 static void tcp_remove_sacks_gt(struct tcp_pcb *pcb, u32_t seq);
-#endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */
+#endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
 #endif /* LWIP_TCP_SACK_OUT */
 
 /**
@@ -1772,23 +1772,35 @@ tcp_receive(struct tcp_pcb *pcb)
           }
 #endif /* LWIP_TCP_SACK_OUT */
         }
-#if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS
+#if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
         {
           /* Check that the data on ooseq doesn't exceed one of the limits
              and throw away everything above that limit. */
+#ifdef TCP_OOSEQ_BYTES_LIMIT
+          const u32_t ooseq_max_blen = TCP_OOSEQ_BYTES_LIMIT(pcb);
           u32_t ooseq_blen = 0;
+#endif
+#ifdef TCP_OOSEQ_PBUFS_LIMIT
+          const u16_t ooseq_max_qlen = TCP_OOSEQ_PBUFS_LIMIT(pcb);
           u16_t ooseq_qlen = 0;
+#endif
           struct tcp_seg *next, *prev = NULL;
           for (next = pcb->ooseq; next != NULL; prev = next, next = next->next) {
             struct pbuf *p = next->p;
-#if TCP_OOSEQ_MAX_BYTES
+            int stop_here = 0;
+#ifdef TCP_OOSEQ_BYTES_LIMIT
             ooseq_blen += p->tot_len;
+            if (ooseq_blen > ooseq_max_blen) {
+              stop_here = 1;
+            }
 #endif
-#if TCP_OOSEQ_MAX_PBUFS
+#ifdef TCP_OOSEQ_PBUFS_LIMIT
             ooseq_qlen += pbuf_clen(p);
+            if (ooseq_qlen > ooseq_max_qlen) {
+              stop_here = 1;
+            }
 #endif
-            if ((ooseq_blen > TCP_OOSEQ_MAX_BYTES) ||
+            if (stop_here) {
-                (ooseq_qlen > TCP_OOSEQ_MAX_PBUFS)) {
 #if LWIP_TCP_SACK_OUT
               if (pcb->flags & TF_SACK) {
                 /* Let's remove all SACKs from next's seqno up. */
@@ -1808,7 +1820,7 @@ tcp_receive(struct tcp_pcb *pcb)
             }
           }
         }
-#endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */
+#endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
 #endif /* TCP_QUEUE_OOSEQ */
 
         /* We send the ACK packet after we've (potentially) dealt with SACKs,
@@ -2074,7 +2086,7 @@ tcp_remove_sacks_lt(struct tcp_pcb *pcb, u32_t seq)
   }
 }
 
-#if TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS
+#if defined(TCP_OOSEQ_BYTES_LIMIT) || defined(TCP_OOSEQ_PBUFS_LIMIT)
 /**
  * Called to remove a range of SACKs.
  *
@@ -2113,7 +2125,7 @@ tcp_remove_sacks_gt(struct tcp_pcb *pcb, u32_t seq)
     pcb->rcv_sacks[i].left = pcb->rcv_sacks[i].right = 0;
   }
 }
-#endif /* TCP_OOSEQ_MAX_BYTES || TCP_OOSEQ_MAX_PBUFS */
+#endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
 
 #endif /* LWIP_TCP_SACK_OUT */
 

src/include/lwip/opt.h

@@ -1300,21 +1300,51 @@
 #endif
 
 /**
- * TCP_OOSEQ_MAX_BYTES: The maximum number of bytes queued on ooseq per pcb.
+ * TCP_OOSEQ_MAX_BYTES: The default maximum number of bytes queued on ooseq per
- * Default is 0 (no limit). Only valid for TCP_QUEUE_OOSEQ==1.
+ * pcb if TCP_OOSEQ_BYTES_LIMIT is not defined. Default is 0 (no limit).
+ * Only valid for TCP_QUEUE_OOSEQ==1.
  */
 #if !defined TCP_OOSEQ_MAX_BYTES || defined __DOXYGEN__
 #define TCP_OOSEQ_MAX_BYTES             0
 #endif
 
 /**
- * TCP_OOSEQ_MAX_PBUFS: The maximum number of pbufs queued on ooseq per pcb.
+ * TCP_OOSEQ_BYTES_LIMIT(pcb): Return the maximum number of bytes to be queued
- * Default is 0 (no limit). Only valid for TCP_QUEUE_OOSEQ==1.
+ * on ooseq per pcb, given the pcb. Only valid for TCP_QUEUE_OOSEQ==1 &&
+ * TCP_OOSEQ_MAX_BYTES==1.
+ * Use this to override TCP_OOSEQ_MAX_BYTES to a dynamic value per pcb.
+ */
+#if !defined TCP_OOSEQ_BYTES_LIMIT
+#if TCP_OOSEQ_MAX_BYTES
+#define TCP_OOSEQ_BYTES_LIMIT(pcb) TCP_OOSEQ_MAX_BYTES
+#elif defined __DOXYGEN__
+#define TCP_OOSEQ_BYTES_LIMIT(pcb)
+#endif
+#endif
+
+/**
+ * TCP_OOSEQ_MAX_PBUFS: The default maximum number of pbufs queued on ooseq per
+ * pcb if TCP_OOSEQ_BYTES_LIMIT is not defined. Default is 0 (no limit).
+ * Only valid for TCP_QUEUE_OOSEQ==1.
  */
 #if !defined TCP_OOSEQ_MAX_PBUFS || defined __DOXYGEN__
 #define TCP_OOSEQ_MAX_PBUFS             0
 #endif
 
+/**
+ * TCP_OOSEQ_PBUFS_LIMIT(pcb): Return the maximum number of pbufs to be queued
+ * on ooseq per pcb, given the pcb.  Only valid for TCP_QUEUE_OOSEQ==1 &&
+ * TCP_OOSEQ_MAX_PBUFS==1.
+ * Use this to override TCP_OOSEQ_MAX_PBUFS to a dynamic value per pcb.
+ */
+#if !defined TCP_OOSEQ_PBUFS_LIMIT
+#if TCP_OOSEQ_MAX_PBUFS
+#define TCP_OOSEQ_PBUFS_LIMIT(pcb) TCP_OOSEQ_MAX_PBUFS
+#elif defined __DOXYGEN__
+#define TCP_OOSEQ_PBUFS_LIMIT(pcb)
+#endif
+#endif
+
 /**
  * TCP_LISTEN_BACKLOG: Enable the backlog option for tcp listen pcb.
  */