[PATCH] 6pack persistence fix
Fix the p-persistence CSMA algorithm which in simplex mode was starting with a slottime delay before doing anything else as if there was carrier collision resulting in bad performance on simplex links. Signed-off-by: Ralf Baechle DL5RB <ralf@linux-mips.org> Acked-by: Jeff Garzik <jgarzik@pobox.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -130,12 +130,11 @@ struct sixpack {
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#define AX25_6PACK_HEADER_LEN 0
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static void sp_start_tx_timer(struct sixpack *);
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static void sixpack_decode(struct sixpack *, unsigned char[], int);
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static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
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/*
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* perform the persistence/slottime algorithm for CSMA access. If the
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* Perform the persistence/slottime algorithm for CSMA access. If the
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* persistence check was successful, write the data to the serial driver.
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* Note that in case of DAMA operation, the data is not sent here.
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*/
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@ -143,7 +142,7 @@ static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
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static void sp_xmit_on_air(unsigned long channel)
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{
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struct sixpack *sp = (struct sixpack *) channel;
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int actual;
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int actual, when = sp->slottime;
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static unsigned char random;
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random = random * 17 + 41;
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@ -159,20 +158,10 @@ static void sp_xmit_on_air(unsigned long channel)
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sp->tty->driver->write(sp->tty, &sp->led_state, 1);
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sp->status2 = 0;
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} else
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sp_start_tx_timer(sp);
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mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
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}
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/* ----> 6pack timer interrupt handler and friends. <---- */
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static void sp_start_tx_timer(struct sixpack *sp)
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{
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int when = sp->slottime;
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del_timer(&sp->tx_t);
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sp->tx_t.data = (unsigned long) sp;
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sp->tx_t.function = sp_xmit_on_air;
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sp->tx_t.expires = jiffies + ((when + 1) * HZ) / 100;
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add_timer(&sp->tx_t);
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}
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/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
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static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
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@ -243,8 +232,7 @@ static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
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sp->xleft = count;
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sp->xhead = sp->xbuff;
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sp->status2 = count;
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if (sp->duplex == 0)
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sp_start_tx_timer(sp);
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sp_xmit_on_air((unsigned long)sp);
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}
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return;
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