[incubator-nuttx] branch master updated: tcp_send_buffered: throttle IOB allocations for send

[ar...@apache.org]

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archer pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-nuttx.git


The following commit(s) were added to refs/heads/master by this push:
     new 09f3a1e  tcp_send_buffered: throttle IOB allocations for send
09f3a1e is described below

commit 09f3a1ec8ed41519207a10fd2a2589ffef348465
Author: YAMAMOTO Takashi <ya...@midokura.com>
AuthorDate: Mon Jul 12 20:05:18 2021 +0900

    tcp_send_buffered: throttle IOB allocations for send
    
    Consider a bi-directional TCP connection:
    
    1. we use all IOBs for tx queue
    2. we advertize zero recv window because we have no free IOBs
    3. if the peer tcp does the same thing,
       both sides advertize zero window and can not drain the tx queue.
    
    For a similar stall to happen, the peer doesn't need to be
    a naive tcp implementation like nuttx. A naive application blocking
    on send() without draining its read buffer is enough.
    (Probably such an application should be fixed to drain rx even
    when tx is full. However, it's another story.)
    
    This commit avoids the situation by prevent tx from grabbing
    the all IOBs in the first place. (assuming CONFIG_IOB_THROTTLE > 0)
---
 net/tcp/tcp.h               | 4 ++--
 net/tcp/tcp_send_buffered.c | 2 +-
 net/tcp/tcp_wrbuffer.c      | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/tcp/tcp.h b/net/tcp/tcp.h
index d2a9975..716e995 100644
--- a/net/tcp/tcp.h
+++ b/net/tcp/tcp.h
@@ -68,10 +68,10 @@
 #  define TCP_WBIOB(wrb)             ((wrb)->wb_iob)
 #  define TCP_WBCOPYOUT(wrb,dest,n)  (iob_copyout(dest,(wrb)->wb_iob,(n),0))
 #  define TCP_WBCOPYIN(wrb,src,n,off) \
-     (iob_copyin((wrb)->wb_iob,src,(n),(off),false,\
+     (iob_copyin((wrb)->wb_iob,src,(n),(off),true,\
                  IOBUSER_NET_TCP_WRITEBUFFER))
 #  define TCP_WBTRYCOPYIN(wrb,src,n,off) \
-     (iob_trycopyin((wrb)->wb_iob,src,(n),(off),false,\
+     (iob_trycopyin((wrb)->wb_iob,src,(n),(off),true,\
                     IOBUSER_NET_TCP_WRITEBUFFER))
 
 #  define TCP_WBTRIM(wrb,n) \
diff --git a/net/tcp/tcp_send_buffered.c b/net/tcp/tcp_send_buffered.c
index a8218d7..5740ad4 100644
--- a/net/tcp/tcp_send_buffered.c
+++ b/net/tcp/tcp_send_buffered.c
@@ -1309,7 +1309,7 @@ int psock_tcp_cansend(FAR struct socket *psock)
    * but we don't know how many more.
    */
 
-  if (tcp_wrbuffer_test() < 0 || iob_navail(false) <= 0)
+  if (tcp_wrbuffer_test() < 0 || iob_navail(true) <= 0)
     {
       return -EWOULDBLOCK;
     }
diff --git a/net/tcp/tcp_wrbuffer.c b/net/tcp/tcp_wrbuffer.c
index c93f749..27d9121 100644
--- a/net/tcp/tcp_wrbuffer.c
+++ b/net/tcp/tcp_wrbuffer.c
@@ -145,7 +145,7 @@ FAR struct tcp_wrbuffer_s *tcp_wrbuffer_alloc(void)
 
   /* Now get the first I/O buffer for the write buffer structure */
 
-  wrb->wb_iob = net_ioballoc(false, IOBUSER_NET_TCP_WRITEBUFFER);
+  wrb->wb_iob = net_ioballoc(true, IOBUSER_NET_TCP_WRITEBUFFER);
 
   /* Did we get an IOB?  We should always get one except under some really
    * weird error conditions.