PPP, removed PPP_INPROC_OWNTHREAD feature, which almost only make things harder

I consider to remove the PPP_INPROC_OWNTHREAD crap in ppp-new,
as said in bugs #37278 and #37353.

1. It requires the ppp_input_thread() function to be modified to match
user system, like some did by adding the vTaskDelete(NULL); FreeRTOS
call at the end of the function, for example.

This is a tiny-tiny fonction that should be, in my opinion, on the user
port, like the Ethernet input thread we see in many Ethernet port.

2. It is actually not that thread safe.

2.1. pcb->phase IS modified by the lwIP core thread so it should at
least be set to volatile, otherwise the pcb->phase copy may live
indefinitely in CPU register. It works because of the sio_read()
function call which without doubt flush pcb->phase copy from CPU
register. I dont want to set ppp_pcb struct to volatile for obvious
performance reasons.

2.2. This function assume PCB still exists whatever is happening, which
is not the case after you called ppp_delete() function outside of this
thread. If sio_read() is blocking waiting data and pcb destroyed, it is
going to read a deallocated pcb which luckily should still have
pcb->phase set to 0 (=PHASE_DEAD) due to preallocated "control block"
structures of lwIP. Even with sio_read_abort(), there might be timings
issue due to a lack of a synchronization mechanism.

3. I dislike the sys_msleep(1), it means that systems should have at
least a 11 chr buffer at 115200/10 byte/s, and bigger with higher serial
speed, for example with 3G/HSDPA modems accessed through SPI, at 20
Mbits/s this is a ~2000 bytes buffer required to keep incoming data
during this sleep, I don't see why we require systems to do so,
sio_read() should obviously be a blocking call. I cannot easily
remove this sleep because some systems might have wrongfully used this
call as a CPU idle feature with a non blocking sio_read() call.

src/include/lwip/opt.h

@@ -1309,31 +1309,6 @@
 #define SLIPIF_THREAD_PRIO              1
 #endif
 
-/**
- * PPP_THREAD_NAME: The name assigned to the pppInputThread.
- */
-#ifndef PPP_THREAD_NAME
-#define PPP_THREAD_NAME                "pppInputThread"
-#endif
-
-/**
- * PPP_THREAD_STACKSIZE: The stack size used by the pppInputThread.
- * The stack size value itself is platform-dependent, but is passed to
- * sys_thread_new() when the thread is created.
- */
-#ifndef PPP_THREAD_STACKSIZE
-#define PPP_THREAD_STACKSIZE            0
-#endif
-
-/**
- * PPP_THREAD_PRIO: The priority assigned to the pppInputThread.
- * The priority value itself is platform-dependent, but is passed to
- * sys_thread_new() when the thread is created.
- */
-#ifndef PPP_THREAD_PRIO
-#define PPP_THREAD_PRIO                 1
-#endif
-
 /**
  * DEFAULT_THREAD_NAME: The name assigned to any other lwIP thread.
  */

src/include/netif/ppp/ppp.h

@@ -50,34 +50,14 @@
 
 #include "vj.h"
 
-/** PPP_INPROC_MULTITHREADED==1 call ppp_input using tcpip_callback().
- * Set this to 0 if pppos_input_proc is called inside tcpip_thread or with NO_SYS==1.
+/** PPP_INPROC_MULTITHREADED==1 call pppos_input using tcpip_callback().
+ * Set this to 0 if pppos_input is called inside tcpip_thread or with NO_SYS==1.
  * Default is 1 for NO_SYS==0 (multithreaded) and 0 for NO_SYS==1 (single-threaded).
  */
 #ifndef PPP_INPROC_MULTITHREADED
 #define PPP_INPROC_MULTITHREADED (NO_SYS==0)
 #endif
 
-/** PPP_INPROC_OWNTHREAD==1: start a dedicated RX thread per PPP session.
- * Default is 1 if PPP_INPROC_MULTITHREADED is enabled.
- * If set to 0, call pppos_input() for received raw characters, character
- * reception is up to the port.
- */
-#ifndef PPP_INPROC_OWNTHREAD
-#define PPP_INPROC_OWNTHREAD      PPP_INPROC_MULTITHREADED
-#endif
-
-#if PPP_INPROC_OWNTHREAD && !PPP_INPROC_MULTITHREADED
-  #error "PPP_INPROC_OWNTHREAD needs PPP_INPROC_MULTITHREADED==1"
-#endif
-
-#if PPPOS_SUPPORT
-/** RX buffer size: this may be configured smaller! */
-#ifndef PPPOS_RX_BUFSIZE
-#define PPPOS_RX_BUFSIZE    (PPP_MRU + PPP_HDRLEN)
-#endif
-#endif /* PPPOS_SUPPORT */
-
 
 /*************************
 *** PUBLIC DEFINITIONS ***
@@ -296,10 +276,6 @@ typedef struct ppp_pcb_rx_s {
   ppp_pcb *pcb;
   /** the rx file descriptor */
   sio_fd_t fd;
-  /** receive buffer - encoded data is stored here */
-#if PPP_INPROC_OWNTHREAD
-  u_char rxbuf[PPPOS_RX_BUFSIZE];
-#endif /* PPPOS_SUPPORT && PPP_INPROC_OWNTHREAD */
 
   /* The input packet. */
   struct pbuf *in_head, *in_tail;
@@ -572,14 +548,12 @@ int ppp_delete(ppp_pcb *pcb);
  */
 int ppp_ioctl(ppp_pcb *pcb, int cmd, void *arg);
 
-#if PPPOS_SUPPORT && !PPP_INPROC_OWNTHREAD
+#if PPPOS_SUPPORT
 /*
  * PPP over Serial: this is the input function to be called for received data.
- * If PPP_INPROC_OWNTHREAD==1, a separate input thread using the blocking
- * sio_read() is used, so this is deactivated.
  */
 void pppos_input(ppp_pcb *pcb, u_char* data, int len);
-#endif /* PPPOS_SUPPORT && !PPP_INPROC_OWNTHREAD */
+#endif /* PPPOS_SUPPORT */
 
 /* Get the PPP netif interface */
 #define ppp_netif(ppp)               (&(ppp)->netif)
@@ -596,21 +570,6 @@ void ppp_set_netif_statuscallback(ppp_pcb *pcb, netif_status_callback_fn status_
 void ppp_set_netif_linkcallback(ppp_pcb *pcb, netif_status_callback_fn link_callback);
 #endif /* LWIP_NETIF_LINK_CALLBACK */
 
-
-/* Source code compatibility */
-#if 0
-#define pppAuthType ppp_auth_type
-#define pppInit() ppp_init()
-#define pppSetAuth(authtype,user,passwd) ppp_set_auth(authtype,user,passwd)
-#define pppOpen(fd,cb,ls) ppp_over_serial_open(fd,cb,ls)
-#define pppOverSerialOpen(fd,cb,ls) ppp_over_serial_open(fd,cb,ls)
-#define pppOverEthernetOpen(ethif,sn,cn,lscb,lsctx) ppp_over_ethernet_open(ethif,sn,cn,lscb,lsctx)
-#define pppClose(unit) ppp_close(unit)
-#define pppSigHUP(unit) ppp_sigup(unit)
-#define pppIOCtl(pd,cmd,arg) ppp_ioctl(pd,cmd,arg)
-#define pppMTU(unit) ppp_mtu(unit)
-#endif
-
 #endif /* PPP_H */
 
 #endif /* PPP_SUPPORT */