Commit c0438174 authored by Ralf Baechle DL5RB's avatar Ralf Baechle DL5RB Committed by Linus Torvalds
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[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: default avatarRalf Baechle DL5RB <ralf@linux-mips.org>
Acked-by: default avatarJeff Garzik <jgarzik@pobox.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 48d28fd5

drivers/net/hamradio/6pack.c

+4 −16
Original line number Diff line number Diff line
@@ -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;

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