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[PATCH] 6pack persistence fix

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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>
This commit is contained in:
Ralf Baechle DL5RB 2005-08-10 10:03:20 -07:00 committed by Linus Torvalds
parent 48d28fd55e
commit c0438174e8
1 changed files with 4 additions and 16 deletions
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20
drivers/net/hamradio/6pack.c
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@ -130,12 +130,11 @@ struct sixpack {
#define AX25_6PACK_HEADER_LEN 0
static void sp_start_tx_timer(struct sixpack *);
static void sixpack_decode(struct sixpack *, unsigned char[], int);
static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
/*
* perform the persistence/slottime algorithm for CSMA access. If the
* Perform the persistence/slottime algorithm for CSMA access. If the
* persistence check was successful, write the data to the serial driver.
* Note that in case of DAMA operation, the data is not sent here.
*/
@ -143,7 +142,7 @@ static int encode_sixpack(unsigned char *, unsigned char *, int, unsigned char);
static void sp_xmit_on_air(unsigned long channel)
{
struct sixpack *sp = (struct sixpack *) channel;
int actual;
int actual, when = sp->slottime;
static unsigned char random;
random = random * 17 + 41;
@ -159,20 +158,10 @@ static void sp_xmit_on_air(unsigned long channel)
sp->tty->driver->write(sp->tty, &sp->led_state, 1);
sp->status2 = 0;
} else
sp_start_tx_timer(sp);
mod_timer(&sp->tx_t, jiffies + ((when + 1) * HZ) / 100);
}
/* ----> 6pack timer interrupt handler and friends. <---- */
static void sp_start_tx_timer(struct sixpack *sp)
{
int when = sp->slottime;
del_timer(&sp->tx_t);
sp->tx_t.data = (unsigned long) sp;
sp->tx_t.function = sp_xmit_on_air;
sp->tx_t.expires = jiffies + ((when + 1) * HZ) / 100;
add_timer(&sp->tx_t);
}
/* Encapsulate one AX.25 frame and stuff into a TTY queue. */
static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
@ -243,8 +232,7 @@ static void sp_encaps(struct sixpack *sp, unsigned char *icp, int len)
sp->xleft = count;
sp->xhead = sp->xbuff;
sp->status2 = count;
if (sp->duplex == 0)
sp_start_tx_timer(sp);
sp_xmit_on_air((unsigned long)sp);
}
return;